Adding upstream version 1:10.5.12.upstream/1%10.5.12upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 9239 insertions, 0 deletions

diff --git a/sql/sql_base.cc b/sql/sql_base.cc
new file mode 100644
index 00000000..a9d7de9a
--- /dev/null
+++ b/sql/sql_base.cc
@@ -0,0 +1,9239 @@
+/* Copyright (c) 2000, 2016, Oracle and/or its affiliates.
+   Copyright (c) 2010, 2021, MariaDB
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; version 2 of the License.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1335  USA */
+
+
+/* Basic functions needed by many modules */
+
+#include "mariadb.h"
+#include "sql_base.h"                           // setup_table_map
+#include "sql_priv.h"
+#include "unireg.h"
+#include "debug_sync.h"
+#include "lock.h"        // mysql_lock_remove,
+                         // mysql_unlock_tables,
+                         // mysql_lock_have_duplicate
+#include "sql_show.h"    // append_identifier
+#include "strfunc.h"     // find_type
+#include "sql_view.h"    // mysql_make_view, VIEW_ANY_ACL
+#include "sql_parse.h"   // check_table_access
+#include "sql_insert.h"  // kill_delayed_threads
+#include "sql_partition.h"               // ALTER_PARTITION_PARAM_TYPE
+#include "sql_derived.h" // mysql_derived_prepare,
+                         // mysql_handle_derived,
+                         // mysql_derived_filling
+#include "sql_handler.h" // mysql_ha_flush
+#include "sql_test.h"
+#include "sql_partition.h"                      // ALTER_PARTITION_PARAM_TYPE
+#include "log_event.h"                          // Query_log_event
+#include "sql_select.h"
+#include "sp_head.h"
+#include "sp.h"
+#include "sp_cache.h"
+#include "sql_trigger.h"
+#include "transaction.h"
+#include "sql_prepare.h"
+#include "sql_statistics.h"
+#include "sql_cte.h"
+#include <m_ctype.h>
+#include <my_dir.h>
+#include <hash.h>
+#include "rpl_filter.h"
+#include "sql_table.h"                          // build_table_filename
+#include "datadict.h"   // dd_frm_is_view()
+#include "rpl_rli.h"   // rpl_group_info
+#ifdef  __WIN__
+#include <io.h>
+#endif
+#include "wsrep_mysqld.h"
+#ifdef WITH_WSREP
+#include "wsrep_thd.h"
+#include "wsrep_trans_observer.h"
+#endif /* WITH_WSREP */
+
+
+bool
+No_such_table_error_handler::handle_condition(THD *,
+                                              uint sql_errno,
+                                              const char*,
+                                              Sql_condition::enum_warning_level *level,
+                                              const char*,
+                                              Sql_condition ** cond_hdl)
+{
+  *cond_hdl= NULL;
+  if (sql_errno == ER_NO_SUCH_TABLE || sql_errno == ER_NO_SUCH_TABLE_IN_ENGINE)
+  {
+    m_handled_errors++;
+    return TRUE;
+  }
+
+  if (*level == Sql_condition::WARN_LEVEL_ERROR)
+    m_unhandled_errors++;
+  return FALSE;
+}
+
+
+bool No_such_table_error_handler::safely_trapped_errors()
+{
+  /*
+    If m_unhandled_errors != 0, something else, unanticipated, happened,
+    so the error is not trapped but returned to the caller.
+    Multiple ER_NO_SUCH_TABLE can be raised in case of views.
+  */
+  return ((m_handled_errors > 0) && (m_unhandled_errors == 0));
+}
+
+
+/**
+  This internal handler is used to trap ER_NO_SUCH_TABLE and
+  ER_WRONG_MRG_TABLE errors during CHECK/REPAIR TABLE for MERGE
+  tables.
+*/
+
+class Repair_mrg_table_error_handler : public Internal_error_handler
+{
+public:
+  Repair_mrg_table_error_handler()
+    : m_handled_errors(false), m_unhandled_errors(false)
+  {}
+
+  bool handle_condition(THD *thd,
+                        uint sql_errno,
+                        const char* sqlstate,
+                        Sql_condition::enum_warning_level *level,
+                        const char* msg,
+                        Sql_condition ** cond_hdl);
+
+  /**
+    Returns TRUE if there were ER_NO_SUCH_/WRONG_MRG_TABLE and there
+    were no unhandled errors. FALSE otherwise.
+  */
+  bool safely_trapped_errors()
+  {
+    /*
+      Check for m_handled_errors is here for extra safety.
+      It can be useful in situation when call to open_table()
+      fails because some error which was suppressed by another
+      error handler (e.g. in case of MDL deadlock which we
+      decided to solve by back-off and retry).
+    */
+    return (m_handled_errors && (! m_unhandled_errors));
+  }
+
+private:
+  bool m_handled_errors;
+  bool m_unhandled_errors;
+};
+
+
+bool
+Repair_mrg_table_error_handler::handle_condition(THD *,
+                                                 uint sql_errno,
+                                                 const char*,
+                                                 Sql_condition::enum_warning_level *level,
+                                                 const char*,
+                                                 Sql_condition ** cond_hdl)
+{
+  *cond_hdl= NULL;
+  if (sql_errno == ER_NO_SUCH_TABLE ||
+      sql_errno == ER_NO_SUCH_TABLE_IN_ENGINE ||
+      sql_errno == ER_WRONG_MRG_TABLE)
+  {
+    m_handled_errors= true;
+    return TRUE;
+  }
+
+  m_unhandled_errors= true;
+  return FALSE;
+}
+
+
+/**
+  @defgroup Data_Dictionary Data Dictionary
+  @{
+*/
+
+static bool check_and_update_table_version(THD *thd, TABLE_LIST *tables,
+                                           TABLE_SHARE *table_share);
+static bool open_table_entry_fini(THD *thd, TABLE_SHARE *share, TABLE *entry);
+static bool auto_repair_table(THD *thd, TABLE_LIST *table_list);
+
+
+/**
+  Get table cache key for a table list element.
+
+  @param table_list[in]  Table list element.
+  @param key[out]        On return points to table cache key for the table.
+
+  @note Unlike create_table_def_key() call this function doesn't construct
+        key in a buffer provided by caller. Instead it relies on the fact
+        that table list element for which key is requested has properly
+        initialized MDL_request object and the fact that table definition
+        cache key is suffix of key used in MDL subsystem. So to get table
+        definition key it simply needs to return pointer to appropriate
+        part of MDL_key object nested in this table list element.
+        Indeed, this means that lifetime of key produced by this call is
+        limited by the lifetime of table list element which it got as
+        parameter.
+
+  @return Length of key.
+*/
+
+uint get_table_def_key(const TABLE_LIST *table_list, const char **key)
+{
+  /*
+    This call relies on the fact that TABLE_LIST::mdl_request::key object
+    is properly initialized, so table definition cache can be produced
+    from key used by MDL subsystem.
+  */
+  DBUG_ASSERT(!strcmp(table_list->get_db_name(),
+                      table_list->mdl_request.key.db_name()));
+  DBUG_ASSERT(!strcmp(table_list->get_table_name(),
+                      table_list->mdl_request.key.name()));
+
+  *key= (const char*)table_list->mdl_request.key.ptr() + 1;
+  return table_list->mdl_request.key.length() - 1;
+}
+
+
+
+/*****************************************************************************
+  Functions to handle table definition cache (TABLE_SHARE)
+*****************************************************************************/
+
+/*
+  Create a list for all open tables matching SQL expression
+
+  SYNOPSIS
+    list_open_tables()
+    thd			Thread THD
+    wild		SQL like expression
+
+  NOTES
+    One gets only a list of tables for which one has any kind of privilege.
+    db and table names are allocated in result struct, so one doesn't need
+    a lock when traversing the return list.
+
+  RETURN VALUES
+    NULL	Error (Probably OOM)
+    #		Pointer to list of names of open tables.
+*/
+
+struct list_open_tables_arg
+{
+  THD *thd;
+  const char *db;
+  const char *wild;
+  TABLE_LIST table_list;
+  OPEN_TABLE_LIST **start_list, *open_list;
+};
+
+
+static my_bool list_open_tables_callback(TDC_element *element,
+                                         list_open_tables_arg *arg)
+{
+  const char *db= (char*) element->m_key;
+  size_t db_length= strlen(db);
+  const char *table_name= db + db_length + 1;
+
+  if (arg->db && my_strcasecmp(system_charset_info, arg->db, db))
+    return FALSE;
+  if (arg->wild && wild_compare(table_name, arg->wild, 0))
+    return FALSE;
+
+  /* Check if user has SELECT privilege for any column in the table */
+  arg->table_list.db.str= db;
+  arg->table_list.db.length= db_length;
+  arg->table_list.table_name.str= table_name;
+  arg->table_list.table_name.length= strlen(table_name);
+  arg->table_list.grant.privilege= NO_ACL;
+
+  if (check_table_access(arg->thd, SELECT_ACL, &arg->table_list, TRUE, 1, TRUE))
+    return FALSE;
+
+  if (!(*arg->start_list= (OPEN_TABLE_LIST *) arg->thd->alloc(
+                    sizeof(**arg->start_list) + element->m_key_length)))
+    return TRUE;
+
+  strmov((*arg->start_list)->table=
+         strmov(((*arg->start_list)->db= (char*) ((*arg->start_list) + 1)),
+                db) + 1, table_name);
+  (*arg->start_list)->in_use= 0;
+
+  mysql_mutex_lock(&element->LOCK_table_share);
+  All_share_tables_list::Iterator it(element->all_tables);
+  TABLE *table;
+  while ((table= it++))
+    if (table->in_use)
+      ++(*arg->start_list)->in_use;
+  mysql_mutex_unlock(&element->LOCK_table_share);
+  (*arg->start_list)->locked= 0;                   /* Obsolete. */
+  arg->start_list= &(*arg->start_list)->next;
+  *arg->start_list= 0;
+  return FALSE;
+}
+
+
+OPEN_TABLE_LIST *list_open_tables(THD *thd, const char *db, const char *wild)
+{
+  list_open_tables_arg argument;
+  DBUG_ENTER("list_open_tables");
+
+  argument.thd= thd;
+  argument.db= db;
+  argument.wild= wild;
+  bzero((char*) &argument.table_list, sizeof(argument.table_list));
+  argument.start_list= &argument.open_list;
+  argument.open_list= 0;
+
+  if (tdc_iterate(thd, (my_hash_walk_action) list_open_tables_callback,
+                  &argument, true))
+    DBUG_RETURN(0);
+
+  DBUG_RETURN(argument.open_list);
+}
+
+
+/**
+   Close all tables that are not in use in table definition cache
+*/
+
+void purge_tables()
+{
+  /*
+    Force close of all open tables.
+
+    Note that code in TABLE_SHARE::wait_for_old_version() assumes that
+    incrementing of refresh_version is followed by purge of unused table
+    shares.
+  */
+  kill_delayed_threads();
+  /*
+    Get rid of all unused TABLE and TABLE_SHARE instances. By doing
+    this we automatically close all tables which were marked as "old".
+  */
+  tc_purge();
+  /* Free table shares which were not freed implicitly by loop above. */
+  tdc_purge(true);
+}
+
+
+/**
+   close_cached_tables
+
+   This function has two separate usages:
+   1) Close not used tables in the table cache to free memory
+   2) Close a list of tables and wait until they are not used anymore. This
+      is used mainly when preparing a table for export.
+
+   If there are locked tables, they are closed and reopened before
+   function returns. This is done to ensure that table files will be closed
+   by all threads and thus external copyable when FLUSH TABLES returns.
+*/
+
+bool close_cached_tables(THD *thd, TABLE_LIST *tables,
+                         bool wait_for_refresh, ulong timeout)
+{
+  DBUG_ENTER("close_cached_tables");
+  DBUG_ASSERT(thd || (!wait_for_refresh && !tables));
+  DBUG_ASSERT(wait_for_refresh || !tables);
+
+  if (!tables)
+  {
+    /* Free tables that are not used */
+    purge_tables();
+    if (!wait_for_refresh)
+      DBUG_RETURN(false);
+  }
+
+  DBUG_PRINT("info", ("open table definitions: %d",
+                      (int) tdc_records()));
+
+  if (thd->locked_tables_mode)
+  {
+    /*
+      If we are under LOCK TABLES, we need to reopen the tables without
+      opening a door for any concurrent threads to sneak in and get
+      lock on our tables. To achieve this we use exclusive metadata
+      locks.
+    */
+    TABLE_LIST *tables_to_reopen= (tables ? tables :
+                                  thd->locked_tables_list.locked_tables());
+    bool result= false;
+
+    /* close open HANDLER for this thread to allow table to be closed */
+    mysql_ha_flush_tables(thd, tables_to_reopen);
+
+    for (TABLE_LIST *table_list= tables_to_reopen; table_list;
+         table_list= table_list->next_global)
+    {
+      int err;
+      /* A check that the table was locked for write is done by the caller. */
+      TABLE *table= find_table_for_mdl_upgrade(thd, table_list->db.str,
+                                            table_list->table_name.str, &err);
+
+      /* May return NULL if this table has already been closed via an alias. */
+      if (! table)
+        continue;
+
+      if (wait_while_table_is_used(thd, table,
+                                   HA_EXTRA_PREPARE_FOR_FORCED_CLOSE))
+      {
+        result= true;
+        break;
+      }
+      close_all_tables_for_name(thd, table->s, HA_EXTRA_NOT_USED, NULL);
+    }
+    /*
+      No other thread has the locked tables open; reopen them and get the
+      old locks. This should always succeed (unless some external process
+      has removed the tables)
+    */
+    if (thd->locked_tables_list.reopen_tables(thd, false))
+      result= true;
+
+    /*
+      Since downgrade_lock() won't do anything with shared
+      metadata lock it is much simpler to go through all open tables rather
+      than picking only those tables that were flushed.
+    */
+    for (TABLE *tab= thd->open_tables; tab; tab= tab->next)
+      tab->mdl_ticket->downgrade_lock(MDL_SHARED_NO_READ_WRITE);
+
+    DBUG_RETURN(result);
+  }
+  else if (tables)
+  {
+    /*
+      Get an explicit MDL lock for all requested tables to ensure they are
+      not used by any other thread
+    */
+    MDL_request_list mdl_requests;
+
+    DBUG_PRINT("info", ("Waiting for other threads to close their open tables"));
+    DEBUG_SYNC(thd, "after_flush_unlock");
+
+    /* close open HANDLER for this thread to allow table to be closed */
+    mysql_ha_flush_tables(thd, tables);
+
+    for (TABLE_LIST *table= tables; table; table= table->next_local)
+    {
+      MDL_request *mdl_request= new (thd->mem_root) MDL_request;
+      if (mdl_request == NULL)
+        DBUG_RETURN(true);
+      MDL_REQUEST_INIT_BY_KEY(mdl_request, &table->mdl_request.key,
+                              MDL_EXCLUSIVE, MDL_STATEMENT);
+      mdl_requests.push_front(mdl_request);
+    }
+
+    if (thd->mdl_context.acquire_locks(&mdl_requests, timeout))
+      DBUG_RETURN(true);
+
+    for (TABLE_LIST *table= tables; table; table= table->next_local)
+      tdc_remove_table(thd, table->db.str, table->table_name.str);
+  }
+  DBUG_RETURN(false);
+}
+
+
+/**
+  Collect all shares that has open tables
+*/
+
+struct tc_collect_arg
+{
+  DYNAMIC_ARRAY shares;
+  flush_tables_type flush_type;
+};
+
+static my_bool tc_collect_used_shares(TDC_element *element,
+                                      tc_collect_arg *arg)
+{
+  my_bool result= FALSE;
+
+  DYNAMIC_ARRAY *shares= &arg->shares;
+  mysql_mutex_lock(&element->LOCK_table_share);
+  if (element->ref_count > 0 && !element->share->is_view)
+  {
+    DBUG_ASSERT(element->share);
+    bool do_flush= 0;
+    switch (arg->flush_type) {
+    case FLUSH_ALL:
+      do_flush= 1;
+      break;
+    case FLUSH_NON_TRANS_TABLES:
+      if (!element->share->online_backup &&
+          element->share->table_category == TABLE_CATEGORY_USER)
+        do_flush= 1;
+      break;
+    case FLUSH_SYS_TABLES:
+      if (!element->share->online_backup &&
+          element->share->table_category != TABLE_CATEGORY_USER)
+        do_flush= 1;
+    }
+    if (do_flush)
+    {
+      element->ref_count++;                       // Protect against delete
+      if (push_dynamic(shares, (uchar*) &element->share))
+        result= TRUE;
+    }
+  }
+  mysql_mutex_unlock(&element->LOCK_table_share);
+  return result;
+}
+
+
+/*
+  Ignore errors from opening read only tables
+*/
+
+class flush_tables_error_handler : public Internal_error_handler
+{
+public:
+  int handled_errors;
+  int unhandled_errors;
+  flush_tables_error_handler() : handled_errors(0), unhandled_errors(0)
+  {}
+
+  bool handle_condition(THD *thd,
+                        uint sql_errno,
+                        const char* sqlstate,
+                        Sql_condition::enum_warning_level *level,
+                        const char* msg,
+                        Sql_condition ** cond_hdl)
+  {
+    *cond_hdl= NULL;
+    if (sql_errno == ER_OPEN_AS_READONLY)
+    {
+      handled_errors++;
+      return TRUE;
+    }
+    if (*level == Sql_condition::WARN_LEVEL_ERROR)
+      unhandled_errors++;
+    return FALSE;
+  }
+
+  bool got_fatal_error()
+  {
+    return unhandled_errors > 0;
+  }
+};
+
+
+/**
+   Flush cached table as part of global read lock
+
+   @param thd
+   @param flag   What type of tables should be flushed
+
+   @return 0  ok
+   @return 1  error
+
+   After we get the list of table shares, we will call flush on all
+   possible tables, even if some flush fails.
+*/
+
+bool flush_tables(THD *thd, flush_tables_type flag)
+{
+  bool result= TRUE;
+  tc_collect_arg collect_arg;
+  TABLE *tmp_table;
+  flush_tables_error_handler error_handler;
+  DBUG_ENTER("flush_tables");
+
+  purge_tables();  /* Flush unused tables and shares */
+
+  /*
+    Loop over all shares and collect shares that have open tables
+    TODO:
+    Optimize this to only collect shares that have been used for
+    write after last time all tables was closed.
+  */
+
+  if (!(tmp_table= (TABLE*) my_malloc(PSI_INSTRUMENT_ME, sizeof(*tmp_table),
+                                      MYF(MY_WME | MY_THREAD_SPECIFIC))))
+    DBUG_RETURN(1);
+
+  my_init_dynamic_array(PSI_INSTRUMENT_ME, &collect_arg.shares,
+                        sizeof(TABLE_SHARE*), 100, 100, MYF(0));
+  collect_arg.flush_type= flag;
+  if (tdc_iterate(thd, (my_hash_walk_action) tc_collect_used_shares,
+                  &collect_arg, true))
+  {
+    /* Release already collected shares */
+    for (uint i= 0 ; i < collect_arg.shares.elements ; i++)
+    {
+      TABLE_SHARE *share= *dynamic_element(&collect_arg.shares, i,
+                                           TABLE_SHARE**);
+      tdc_release_share(share);
+    }
+    goto err;
+  }
+
+  /* Call HA_EXTRA_FLUSH on all found shares */
+
+  thd->push_internal_handler(&error_handler);
+  for (uint i= 0 ; i < collect_arg.shares.elements ; i++)
+  {
+    TABLE_SHARE *share= *dynamic_element(&collect_arg.shares, i,
+                                         TABLE_SHARE**);
+    TABLE *table= tc_acquire_table(thd, share->tdc);
+    if (table)
+    {
+      (void) table->file->extra(HA_EXTRA_FLUSH);
+      tc_release_table(table);
+    }
+    else
+    {
+      /*
+        HA_OPEN_FOR_FLUSH is used to allow us to open the table even if
+        TABLE_SHARE::incompatible_version is set. It also will tell
+        SEQUENCE engine that we don't have to read the sequence information
+        (which may cause deadlocks with concurrently running ALTER TABLE or
+        ALTER SEQUENCE) as we will close the table at once.
+      */
+      if (!open_table_from_share(thd, share, &empty_clex_str,
+                                 HA_OPEN_KEYFILE, 0,
+                                 HA_OPEN_FOR_ALTER | HA_OPEN_FOR_FLUSH,
+                                 tmp_table, FALSE,
+                                 NULL))
+      {
+        (void) tmp_table->file->extra(HA_EXTRA_FLUSH);
+        /*
+          We don't put the table into the TDC as the table was not fully
+          opened (we didn't open triggers)
+        */
+        closefrm(tmp_table);
+      }
+    }
+    tdc_release_share(share);
+  }
+  thd->pop_internal_handler();
+  result= error_handler.got_fatal_error();
+  DBUG_PRINT("note", ("open_errors: %u %u",
+                      error_handler.handled_errors,
+                      error_handler.unhandled_errors));
+err:
+  my_free(tmp_table);
+  delete_dynamic(&collect_arg.shares);
+  DBUG_RETURN(result);
+}
+
+
+/*
+  Mark all tables in the list which were used by current substatement
+  as free for reuse.
+
+  SYNOPSIS
+    mark_used_tables_as_free_for_reuse()
+      thd   - thread context
+      table - head of the list of tables
+
+  DESCRIPTION
+    Marks all tables in the list which were used by current substatement
+    (they are marked by its query_id) as free for reuse.
+
+    Clear 'check_table_binlog_row_based_done' flag. For tables which were used
+    by current substatement the flag is cleared as part of 'ha_reset()' call.
+    For the rest of the open tables not used by current substament if this
+    flag is enabled as part of current substatement execution,
+    (for example when THD::binlog_write_table_maps() calls
+    prepare_for_row_logging()), clear the flag explicitly.
+
+  NOTE
+    The reason we reset query_id is that it's not enough to just test
+    if table->query_id != thd->query_id to know if a table is in use.
+
+    For example
+    SELECT f1_that_uses_t1() FROM t1;
+    In f1_that_uses_t1() we will see one instance of t1 where query_id is
+    set to query_id of original query.
+*/
+
+static void mark_used_tables_as_free_for_reuse(THD *thd, TABLE *table)
+{
+  DBUG_ENTER("mark_used_tables_as_free_for_reuse");
+  for (; table ; table= table->next)
+  {
+    DBUG_ASSERT(table->pos_in_locked_tables == NULL ||
+                table->pos_in_locked_tables->table == table);
+    if (table->query_id == thd->query_id)
+    {
+      table->query_id= 0;
+      table->file->ha_reset();
+    }
+    else
+      table->file->clear_cached_table_binlog_row_based_flag();
+  }
+  DBUG_VOID_RETURN;
+}
+
+
+/**
+  Close all open instances of the table but keep the MDL lock.
+
+  Works both under LOCK TABLES and in the normal mode.
+  Removes all closed instances of the table from the table cache.
+
+  @param     thd     thread handle
+  @param[in] share   table share, but is just a handy way to
+                     access the table cache key
+
+  @param[in] extra
+                     HA_EXTRA_PREPARE_FOR_DROP
+                        - The table is dropped
+                     HA_EXTRA_PREPARE_FOR_RENAME
+                        - The table is renamed
+                     HA_EXTRA_NOT_USED
+                        - The table is marked as closed in the
+                          locked_table_list but kept there so one can call
+                          locked_table_list->reopen_tables() to put it back.
+
+                     In case of drop/rename the documented behavior is to
+                     implicitly remove the table from LOCK TABLES
+                     list. 
+
+  @pre Must be called with an X MDL lock on the table.
+*/
+
+void
+close_all_tables_for_name(THD *thd, TABLE_SHARE *share,
+                          ha_extra_function extra,
+                          TABLE *skip_table)
+{
+  DBUG_ASSERT(!share->tmp_table);
+  DBUG_ASSERT(share->tdc->flushed);
+
+  char key[MAX_DBKEY_LENGTH];
+  size_t key_length= share->table_cache_key.length;
+  bool remove_from_locked_tables= extra != HA_EXTRA_NOT_USED;
+
+  memcpy(key, share->table_cache_key.str, key_length);
+
+  for (TABLE **prev= &thd->open_tables; *prev; )
+  {
+    TABLE *table= *prev;
+
+    if (table->s->table_cache_key.length == key_length &&
+        !memcmp(table->s->table_cache_key.str, key, key_length) &&
+        table != skip_table)
+    {
+      thd->locked_tables_list.unlink_from_list(thd,
+                                               table->pos_in_locked_tables,
+                                               remove_from_locked_tables);
+      /* Inform handler that there is a drop table or a rename going on */
+      if (extra != HA_EXTRA_NOT_USED && table->db_stat)
+      {
+        table->file->extra(extra);
+        extra= HA_EXTRA_NOT_USED;               // Call extra once!
+      }
+
+      /*
+        Does nothing if the table is not locked.
+        This allows one to use this function after a table
+        has been unlocked, e.g. in partition management.
+      */
+      mysql_lock_remove(thd, thd->lock, table);
+      close_thread_table(thd, prev);
+    }
+    else
+    {
+      /* Step to next entry in open_tables list. */
+      prev= &table->next;
+    }
+  }
+}
+
+
+/*
+  Close all tables used by the current substatement, or all tables
+  used by this thread if we are on the upper level.
+
+  SYNOPSIS
+    close_thread_tables()
+    thd			Thread handler
+
+  IMPLEMENTATION
+    Unlocks tables and frees derived tables.
+    Put all normal tables used by thread in free list.
+
+    It will only close/mark as free for reuse tables opened by this
+    substatement, it will also check if we are closing tables after
+    execution of complete query (i.e. we are on upper level) and will
+    leave prelocked mode if needed.
+*/
+
+int close_thread_tables(THD *thd)
+{
+  TABLE *table;
+  int error= 0;
+  DBUG_ENTER("close_thread_tables");
+
+  THD_STAGE_INFO(thd, stage_closing_tables);
+
+#ifdef EXTRA_DEBUG
+  DBUG_PRINT("tcache", ("open tables:"));
+  for (table= thd->open_tables; table; table= table->next)
+    DBUG_PRINT("tcache", ("table: '%s'.'%s' %p", table->s->db.str,
+                          table->s->table_name.str, table));
+#endif
+
+#if defined(ENABLED_DEBUG_SYNC)
+  /* debug_sync may not be initialized for some slave threads */
+  if (thd->debug_sync_control)
+    DEBUG_SYNC(thd, "before_close_thread_tables");
+#endif
+
+  DBUG_ASSERT(thd->transaction->stmt.is_empty() || thd->in_sub_stmt ||
+              (thd->state_flags & Open_tables_state::BACKUPS_AVAIL));
+
+  for (table= thd->open_tables; table; table= table->next)
+  {
+    /* Table might be in use by some outer statement. */
+    DBUG_PRINT("tcache", ("table: '%s'  query_id: %lu",
+                          table->s->table_name.str, (ulong) table->query_id));
+
+    /* Detach MERGE children after every statement. Even under LOCK TABLES. */
+    if (thd->locked_tables_mode <= LTM_LOCK_TABLES ||
+        table->query_id == thd->query_id)
+    {
+      DBUG_ASSERT(table->file);
+      table->file->extra(HA_EXTRA_DETACH_CHILDREN);
+    }
+  }
+
+  /*
+    We are assuming here that thd->derived_tables contains ONLY derived
+    tables for this substatement. i.e. instead of approach which uses
+    query_id matching for determining which of the derived tables belong
+    to this substatement we rely on the ability of substatements to
+    save/restore thd->derived_tables during their execution.
+
+    TODO: Probably even better approach is to simply associate list of
+          derived tables with (sub-)statement instead of thread and destroy
+          them at the end of its execution.
+  */
+  if (thd->derived_tables)
+  {
+    TABLE *next;
+    /*
+      Close all derived tables generated in queries like
+      SELECT * FROM (SELECT * FROM t1)
+    */
+    for (table= thd->derived_tables ; table ; table= next)
+    {
+      next= table->next;
+      free_tmp_table(thd, table);
+    }
+    thd->derived_tables= 0;
+  }
+
+  if (thd->rec_tables)
+  {
+    TABLE *next;
+    /*
+      Close all temporary tables created for recursive table references.
+      This action was postponed because the table could be used in the
+      statements like  ANALYZE WITH r AS (...) SELECT * from r
+      where r is defined through recursion. 
+    */
+    for (table= thd->rec_tables ; table ; table= next)
+    {
+      next= table->next;
+      free_tmp_table(thd, table);
+    }
+    thd->rec_tables= 0;
+  }
+
+  /*
+    Mark all temporary tables used by this statement as free for reuse.
+  */
+  thd->mark_tmp_tables_as_free_for_reuse();
+
+  if (thd->locked_tables_mode)
+  {
+
+    /* Ensure we are calling ha_reset() for all used tables */
+    mark_used_tables_as_free_for_reuse(thd, thd->open_tables);
+
+    /*
+      We are under simple LOCK TABLES or we're inside a sub-statement
+      of a prelocked statement, so should not do anything else.
+
+      Note that even if we are in LTM_LOCK_TABLES mode and statement
+      requires prelocking (e.g. when we are closing tables after
+      failing ot "open" all tables required for statement execution)
+      we will exit this function a few lines below.
+    */
+    if (! thd->lex->requires_prelocking())
+      DBUG_RETURN(0);
+
+    /*
+      We are in the top-level statement of a prelocked statement,
+      so we have to leave the prelocked mode now with doing implicit
+      UNLOCK TABLES if needed.
+    */
+    if (thd->locked_tables_mode == LTM_PRELOCKED_UNDER_LOCK_TABLES)
+      thd->locked_tables_mode= LTM_LOCK_TABLES;
+
+    if (thd->locked_tables_mode == LTM_LOCK_TABLES)
+      DBUG_RETURN(0);
+
+    thd->leave_locked_tables_mode();
+
+    /* Fallthrough */
+  }
+
+  if (thd->lock)
+  {
+    /*
+      For RBR we flush the pending event just before we unlock all the
+      tables.  This means that we are at the end of a topmost
+      statement, so we ensure that the STMT_END_F flag is set on the
+      pending event.  For statements that are *inside* stored
+      functions, the pending event will not be flushed: that will be
+      handled either before writing a query log event (inside
+      binlog_query()) or when preparing a pending event.
+     */
+    (void)thd->binlog_flush_pending_rows_event(TRUE);
+    error= mysql_unlock_tables(thd, thd->lock);
+    thd->lock=0;
+  }
+  /*
+    Closing a MERGE child before the parent would be fatal if the
+    other thread tries to abort the MERGE lock in between.
+  */
+  while (thd->open_tables)
+    (void) close_thread_table(thd, &thd->open_tables);
+
+  DBUG_RETURN(error);
+}
+
+
+/* move one table to free list */
+
+void close_thread_table(THD *thd, TABLE **table_ptr)
+{
+  TABLE *table= *table_ptr;
+  DBUG_ENTER("close_thread_table");
+  DBUG_PRINT("tcache", ("table: '%s'.'%s' %p", table->s->db.str,
+                        table->s->table_name.str, table));
+  DBUG_ASSERT(!table->file->keyread_enabled());
+  DBUG_ASSERT(!table->file || table->file->inited == handler::NONE);
+
+  /*
+    The metadata lock must be released after giving back
+    the table to the table cache.
+  */
+  DBUG_ASSERT(thd->mdl_context.is_lock_owner(MDL_key::TABLE,
+                                             table->s->db.str,
+                                             table->s->table_name.str,
+                                             MDL_SHARED));
+  table->mdl_ticket= NULL;
+
+  if (table->file)
+  {
+    table->file->update_global_table_stats();
+    table->file->update_global_index_stats();
+  }
+
+  /*
+    This look is needed to allow THD::notify_shared_lock() to
+    traverse the thd->open_tables list without having to worry that
+    some of the tables are removed from under it
+  */
+
+  mysql_mutex_lock(&thd->LOCK_thd_data);
+  *table_ptr=table->next;
+  mysql_mutex_unlock(&thd->LOCK_thd_data);
+
+  if (! table->needs_reopen())
+  {
+    /* Avoid having MERGE tables with attached children in table cache. */
+    table->file->extra(HA_EXTRA_DETACH_CHILDREN);
+    /* Free memory and reset for next loop. */
+    free_field_buffers_larger_than(table, MAX_TDC_BLOB_SIZE);
+    table->file->ha_reset();
+  }
+
+  /*
+    Do this *before* entering the TABLE_SHARE::tdc.LOCK_table_share
+    critical section.
+  */
+  MYSQL_UNBIND_TABLE(table->file);
+
+  tc_release_table(table);
+  DBUG_VOID_RETURN;
+}
+
+
+/*
+  Find table in list.
+
+  SYNOPSIS
+    find_table_in_list()
+    table		Pointer to table list
+    offset		Offset to which list in table structure to use
+    db_name		Data base name
+    table_name		Table name
+
+  NOTES:
+    This is called by find_table_in_global_list().
+
+  RETURN VALUES
+    NULL	Table not found
+    #		Pointer to found table.
+*/
+
+TABLE_LIST *find_table_in_list(TABLE_LIST *table,
+                               TABLE_LIST *TABLE_LIST::*link,
+                               const LEX_CSTRING *db_name,
+                               const LEX_CSTRING *table_name)
+{
+  for (; table; table= table->*link )
+  {
+    if (cmp(&table->db, db_name) == 0 &&
+        cmp(&table->table_name, table_name) == 0)
+      break;
+  }
+  return table;
+}
+
+
+/**
+  Test that table is unique (It's only exists once in the table list)
+
+  @param  thd                   thread handle
+  @param  table                 table which should be checked
+  @param  table_list            list of tables
+  @param  check_flag            whether to check tables' aliases
+                                Currently this is only used by INSERT
+
+  NOTE: to exclude derived tables from check we use following mechanism:
+    a) during derived table processing set THD::derived_tables_processing
+    b) JOIN::prepare set SELECT::exclude_from_table_unique_test if
+       THD::derived_tables_processing set. (we can't use JOIN::execute
+       because for PS we perform only JOIN::prepare, but we can't set this
+       flag in JOIN::prepare if we are not sure that we are in derived table
+       processing loop, because multi-update call fix_fields() for some its
+       items (which mean JOIN::prepare for subqueries) before unique_table
+       call to detect which tables should be locked for write).
+    c) find_dup_table skip all tables which belong to SELECT with
+       SELECT::exclude_from_table_unique_test set.
+    Also SELECT::exclude_from_table_unique_test used to exclude from check
+    tables of main SELECT of multi-delete and multi-update
+
+    We also skip tables with TABLE_LIST::prelocking_placeholder set,
+    because we want to allow SELECTs from them, and their modification
+    will rise the error anyway.
+
+    TODO: when we will have table/view change detection we can do this check
+          only once for PS/SP
+
+  @retval !=0  found duplicate
+  @retval 0 if table is unique
+*/
+
+static
+TABLE_LIST* find_dup_table(THD *thd, TABLE_LIST *table, TABLE_LIST *table_list,
+                           uint check_flag)
+{
+  TABLE_LIST *res= 0;
+  LEX_CSTRING *d_name, *t_name, *t_alias;
+  DBUG_ENTER("find_dup_table");
+  DBUG_PRINT("enter", ("table alias: %s", table->alias.str));
+
+  /*
+    If this function called for query which update table (INSERT/UPDATE/...)
+    then we have in table->table pointer to TABLE object which we are
+    updating even if it is VIEW so we need TABLE_LIST of this TABLE object
+    to get right names (even if lower_case_table_names used).
+
+    If this function called for CREATE command that we have not opened table
+    (table->table equal to 0) and right names is in current TABLE_LIST
+    object.
+  */
+  if (table->table)
+  {
+    /* All MyISAMMRG children are plain MyISAM tables. */
+    DBUG_ASSERT(table->table->file->ht->db_type != DB_TYPE_MRG_MYISAM);
+
+    table= table->find_underlying_table(table->table);
+    /*
+      as far as we have table->table we have to find real TABLE_LIST of
+      it in underlying tables
+    */
+    DBUG_ASSERT(table);
+  }
+  d_name= &table->db;
+  t_name= &table->table_name;
+  t_alias= &table->alias;
+
+retry:
+  DBUG_PRINT("info", ("real table: %s.%s", d_name->str, t_name->str));
+  for (TABLE_LIST *tl= table_list; tl ; tl= tl->next_global, res= 0)
+  {
+    if (tl->select_lex && tl->select_lex->master_unit() &&
+        tl->select_lex->master_unit()->executed)
+    {
+      /*
+        There is no sense to check tables of already executed parts
+        of the query
+      */
+      continue;
+    }
+    /*
+      Table is unique if it is present only once in the global list
+      of tables and once in the list of table locks.
+    */
+    if (! (res= find_table_in_global_list(tl, d_name, t_name)))
+      break;
+    tl= res;                       // We can continue search after this table
+
+    /* Skip if same underlying table. */
+    if (res->table && (res->table == table->table))
+      continue;
+
+    /* Skip if table is tmp table */
+    if (check_flag & CHECK_DUP_SKIP_TEMP_TABLE &&
+        res->table && res->table->s->tmp_table != NO_TMP_TABLE)
+    {
+      continue;
+    }
+    if (check_flag & CHECK_DUP_FOR_CREATE)
+      DBUG_RETURN(res);
+
+    /* Skip if table alias does not match. */
+    if (check_flag & CHECK_DUP_ALLOW_DIFFERENT_ALIAS)
+    {
+      if (my_strcasecmp(table_alias_charset, t_alias->str, res->alias.str))
+        continue;
+    }
+
+    /*
+      If table is not excluded (could be a derived table) and table is not
+      a prelocking placeholder then we found either a duplicate entry
+      or a table that is part of a derived table (handled below).
+      Examples are:
+      INSERT INTO t1 SELECT * FROM t1;
+      INSERT INTO t1 SELECT * FROM view_containing_t1;
+    */
+    if (res->select_lex &&
+        !res->select_lex->exclude_from_table_unique_test &&
+        !res->prelocking_placeholder)
+      break;
+
+    /*
+      If we found entry of this table or table of SELECT which already
+      processed in derived table or top select of multi-update/multi-delete
+      (exclude_from_table_unique_test) or prelocking placeholder.
+    */
+    DBUG_PRINT("info",
+               ("found same copy of table or table which we should skip"));
+  }
+  if (res && res->belong_to_derived)
+  {
+    /*
+      We come here for queries of type:
+      INSERT INTO t1 (SELECT tmp.a FROM (select * FROM t1) as tmp);
+
+      Try to fix by materializing the derived table
+    */
+    TABLE_LIST *derived=  res->belong_to_derived;
+    if (derived->is_merged_derived() && !derived->derived->is_excluded())
+    {
+      DBUG_PRINT("info",
+                 ("convert merged to materialization to resolve the conflict"));
+      derived->change_refs_to_fields();
+      derived->set_materialized_derived();
+      goto retry;
+    }
+  }
+  DBUG_RETURN(res);
+}
+
+
+/**
+  Test that the subject table of INSERT/UPDATE/DELETE/CREATE
+  or (in case of MyISAMMRG) one of its children are not used later
+  in the query.
+
+  For MyISAMMRG tables, it is assumed that all the underlying
+  tables of @c table (if any) are listed right after it and that
+  their @c parent_l field points at the main table.
+
+
+  @retval non-NULL The table list element for the table that
+                   represents the duplicate. 
+  @retval NULL     No duplicates found.
+*/
+
+TABLE_LIST*
+unique_table(THD *thd, TABLE_LIST *table, TABLE_LIST *table_list,
+             uint check_flag)
+{
+  TABLE_LIST *dup;
+
+  table= table->find_table_for_update();
+
+  if (table->table &&
+      table->table->file->ha_table_flags() & HA_CAN_MULTISTEP_MERGE)
+  {
+    TABLE_LIST *child;
+    dup= NULL;
+    /* Check duplicates of all merge children. */
+    for (child= table->next_global; child;
+         child= child->next_global)
+    {
+      if (child->table &&
+          child->table->file->ha_table_flags() & HA_CAN_MULTISTEP_MERGE)
+        continue;
+
+      /*
+        Ensure that the child has one parent that is the table that is
+        updated.
+      */
+      TABLE_LIST *tmp_parent= child;
+      while ((tmp_parent= tmp_parent->parent_l))
+      {
+        if (tmp_parent == table)
+          break;
+      }
+      if (!tmp_parent)
+        break;
+
+      if ((dup= find_dup_table(thd, child, child->next_global, check_flag)))
+        break;
+    }
+  }
+  else
+    dup= find_dup_table(thd, table, table_list, check_flag);
+  return dup;
+}
+
+
+/*
+  Issue correct error message in case we found 2 duplicate tables which
+  prevent some update operation
+
+  SYNOPSIS
+    update_non_unique_table_error()
+    update      table which we try to update
+    operation   name of update operation
+    duplicate   duplicate table which we found
+
+  NOTE:
+    here we hide view underlying tables if we have them
+*/
+
+void update_non_unique_table_error(TABLE_LIST *update,
+                                   const char *operation,
+                                   TABLE_LIST *duplicate)
+{
+  update= update->top_table();
+  duplicate= duplicate->top_table();
+  if (!update->view || !duplicate->view ||
+      update->view == duplicate->view ||
+      update->view_name.length != duplicate->view_name.length ||
+      update->view_db.length != duplicate->view_db.length ||
+      lex_string_cmp(table_alias_charset,
+                     &update->view_name, &duplicate->view_name) != 0 ||
+      lex_string_cmp(table_alias_charset,
+                     &update->view_db, &duplicate->view_db) != 0)
+  {
+    /*
+      it is not the same view repeated (but it can be parts of the same copy
+      of view), so we have to hide underlying tables.
+    */
+    if (update->view)
+    {
+      /* Issue the ER_NON_INSERTABLE_TABLE error for an INSERT */
+      if (update->view == duplicate->view)
+        my_error(!strncmp(operation, "INSERT", 6) ?
+                 ER_NON_INSERTABLE_TABLE : ER_NON_UPDATABLE_TABLE, MYF(0),
+                 update->alias.str, operation);
+      else
+        my_error(ER_VIEW_PREVENT_UPDATE, MYF(0),
+                 (duplicate->view ? duplicate->alias.str : update->alias.str),
+                 operation, update->alias.str);
+      return;
+    }
+    if (duplicate->view)
+    {
+      my_error(ER_VIEW_PREVENT_UPDATE, MYF(0), duplicate->alias.str, operation,
+               update->alias.str);
+      return;
+    }
+  }
+  my_error(ER_UPDATE_TABLE_USED, MYF(0), update->alias.str, operation);
+}
+
+
+/**
+   Force all other threads to stop using the table by upgrading
+   metadata lock on it and remove unused TABLE instances from cache.
+
+   @param thd      Thread handler
+   @param table    Table to remove from cache
+   @param function HA_EXTRA_PREPARE_FOR_DROP if table is to be deleted
+                   HA_EXTRA_FORCE_REOPEN if table is not be used
+                   HA_EXTRA_PREPARE_FOR_RENAME if table is to be renamed
+                   HA_EXTRA_NOT_USED             Don't call extra()
+
+   @note When returning, the table will be unusable for other threads
+         until metadata lock is downgraded.
+
+   @retval FALSE Success.
+   @retval TRUE  Failure (e.g. because thread was killed).
+*/
+
+bool wait_while_table_is_used(THD *thd, TABLE *table,
+                              enum ha_extra_function function)
+{
+  DBUG_ENTER("wait_while_table_is_used");
+  DBUG_ASSERT(!table->s->tmp_table);
+  DBUG_PRINT("enter", ("table: '%s'  share: %p  db_stat: %u",
+                       table->s->table_name.str, table->s,
+                       table->db_stat));
+
+  if (thd->mdl_context.upgrade_shared_lock(
+             table->mdl_ticket, MDL_EXCLUSIVE,
+             thd->variables.lock_wait_timeout))
+    DBUG_RETURN(TRUE);
+
+  table->s->tdc->flush(thd, true);
+  /* extra() call must come only after all instances above are closed */
+  if (function != HA_EXTRA_NOT_USED)
+  {
+    int error= table->file->extra(function);
+    if (error)
+      table->file->print_error(error, MYF(0));
+    DBUG_RETURN(error);
+  }
+  DBUG_RETURN(FALSE);
+}
+
+
+/**
+  Close a and drop a just created table in CREATE TABLE ... SELECT.
+
+  @param  thd         Thread handle
+  @param  table       TABLE object for the table to be dropped
+  @param  db_name     Name of database for this table
+  @param  table_name  Name of this table
+
+  This routine assumes that the table to be closed is open only
+  by the calling thread, so we needn't wait until other threads
+  close the table. It also assumes that the table is first
+  in thd->open_ables and a data lock on it, if any, has been
+  released. To sum up, it's tuned to work with
+  CREATE TABLE ... SELECT and CREATE TABLE .. SELECT only.
+  Note, that currently CREATE TABLE ... SELECT is not supported
+  under LOCK TABLES. This function, still, can be called in
+  prelocked mode, e.g. if we do CREATE TABLE .. SELECT f1();
+*/
+
+void drop_open_table(THD *thd, TABLE *table, const LEX_CSTRING *db_name,
+                     const LEX_CSTRING *table_name)
+{
+  DBUG_ENTER("drop_open_table");
+  if (table->s->tmp_table)
+    thd->drop_temporary_table(table, NULL, true);
+  else
+  {
+    DBUG_ASSERT(table == thd->open_tables);
+
+    handlerton *table_type= table->s->db_type();
+    table->file->extra(HA_EXTRA_PREPARE_FOR_DROP);
+    table->s->tdc->flush(thd, true);
+    close_thread_table(thd, &thd->open_tables);
+    /* Remove the table from the storage engine and rm the .frm. */
+    quick_rm_table(thd, table_type, db_name, table_name, 0);
+ }
+  DBUG_VOID_RETURN;
+}
+
+
+/**
+  An error handler which converts, if possible, ER_LOCK_DEADLOCK error
+  that can occur when we are trying to acquire a metadata lock to
+  a request for back-off and re-start of open_tables() process.
+*/
+
+class MDL_deadlock_handler : public Internal_error_handler
+{
+public:
+  MDL_deadlock_handler(Open_table_context *ot_ctx_arg)
+    : m_ot_ctx(ot_ctx_arg), m_is_active(FALSE)
+  {}
+
+  virtual ~MDL_deadlock_handler() {}
+
+  virtual bool handle_condition(THD *thd,
+                                uint sql_errno,
+                                const char* sqlstate,
+                                Sql_condition::enum_warning_level *level,
+                                const char* msg,
+                                Sql_condition ** cond_hdl);
+
+private:
+  /** Open table context to be used for back-off request. */
+  Open_table_context *m_ot_ctx;
+  /**
+    Indicates that we are already in the process of handling
+    ER_LOCK_DEADLOCK error. Allows to re-emit the error from
+    the error handler without falling into infinite recursion.
+  */
+  bool m_is_active;
+};
+
+
+bool MDL_deadlock_handler::handle_condition(THD *,
+                                            uint sql_errno,
+                                            const char*,
+                                            Sql_condition::enum_warning_level*,
+                                            const char*,
+                                            Sql_condition ** cond_hdl)
+{
+  *cond_hdl= NULL;
+  if (! m_is_active && sql_errno == ER_LOCK_DEADLOCK)
+  {
+    /* Disable the handler to avoid infinite recursion. */
+    m_is_active= TRUE;
+    (void) m_ot_ctx->request_backoff_action(
+             Open_table_context::OT_BACKOFF_AND_RETRY,
+             NULL);
+    m_is_active= FALSE;
+    /*
+      If the above back-off request failed, a new instance of
+      ER_LOCK_DEADLOCK error was emitted. Thus the current
+      instance of error condition can be treated as handled.
+    */
+    return TRUE;
+  }
+  return FALSE;
+}
+
+
+/**
+  Try to acquire an MDL lock for a table being opened.
+
+  @param[in,out] thd      Session context, to report errors.
+  @param[out]    ot_ctx   Open table context, to hold the back off
+                          state. If we failed to acquire a lock
+                          due to a lock conflict, we add the
+                          failed request to the open table context.
+  @param[in,out] mdl_request A request for an MDL lock.
+                          If we managed to acquire a ticket
+                          (no errors or lock conflicts occurred),
+                          contains a reference to it on
+                          return. However, is not modified if MDL
+                          lock type- modifying flags were provided.
+  @param[in]    flags flags MYSQL_OPEN_FORCE_SHARED_MDL,
+                          MYSQL_OPEN_FORCE_SHARED_HIGH_PRIO_MDL or
+                          MYSQL_OPEN_FAIL_ON_MDL_CONFLICT
+                          @sa open_table().
+  @param[out]   mdl_ticket Only modified if there was no error.
+                          If we managed to acquire an MDL
+                          lock, contains a reference to the
+                          ticket, otherwise is set to NULL.
+
+  @retval TRUE  An error occurred.
+  @retval FALSE No error, but perhaps a lock conflict, check mdl_ticket.
+*/
+
+static bool
+open_table_get_mdl_lock(THD *thd, Open_table_context *ot_ctx,
+                        MDL_request *mdl_request,
+                        uint flags,
+                        MDL_ticket **mdl_ticket)
+{
+  MDL_request mdl_request_shared;
+
+  if (flags & (MYSQL_OPEN_FORCE_SHARED_MDL |
+               MYSQL_OPEN_FORCE_SHARED_HIGH_PRIO_MDL))
+  {
+    /*
+      MYSQL_OPEN_FORCE_SHARED_MDL flag means that we are executing
+      PREPARE for a prepared statement and want to override
+      the type-of-operation aware metadata lock which was set
+      in the parser/during view opening with a simple shared
+      metadata lock.
+      This is necessary to allow concurrent execution of PREPARE
+      and LOCK TABLES WRITE statement against the same table.
+
+      MYSQL_OPEN_FORCE_SHARED_HIGH_PRIO_MDL flag means that we open
+      the table in order to get information about it for one of I_S
+      queries and also want to override the type-of-operation aware
+      shared metadata lock which was set earlier (e.g. during view
+      opening) with a high-priority shared metadata lock.
+      This is necessary to avoid unnecessary waiting and extra
+      ER_WARN_I_S_SKIPPED_TABLE warnings when accessing I_S tables.
+
+      These two flags are mutually exclusive.
+    */
+    DBUG_ASSERT(!(flags & MYSQL_OPEN_FORCE_SHARED_MDL) ||
+                !(flags & MYSQL_OPEN_FORCE_SHARED_HIGH_PRIO_MDL));
+
+    MDL_REQUEST_INIT_BY_KEY(&mdl_request_shared, &mdl_request->key,
+        flags & MYSQL_OPEN_FORCE_SHARED_MDL ? MDL_SHARED : MDL_SHARED_HIGH_PRIO,
+        MDL_TRANSACTION);
+    mdl_request= &mdl_request_shared;
+  }
+
+  if (flags & MYSQL_OPEN_FAIL_ON_MDL_CONFLICT)
+  {
+    /*
+      When table is being open in order to get data for I_S table,
+      we might have some tables not only open but also locked (e.g. when
+      this happens under LOCK TABLES or in a stored function).
+      As a result by waiting on a conflicting metadata lock to go away
+      we may create a deadlock which won't entirely belong to the
+      MDL subsystem and thus won't be detectable by this subsystem's
+      deadlock detector.
+      To avoid such situation we skip the trouble-making table if
+      there is a conflicting lock.
+    */
+    if (thd->mdl_context.try_acquire_lock(mdl_request))
+      return TRUE;
+    if (mdl_request->ticket == NULL)
+    {
+      my_error(ER_WARN_I_S_SKIPPED_TABLE, MYF(0),
+               mdl_request->key.db_name(), mdl_request->key.name());
+      return TRUE;
+    }
+  }
+  else
+  {
+    /*
+      We are doing a normal table open. Let us try to acquire a metadata
+      lock on the table. If there is a conflicting lock, acquire_lock()
+      will wait for it to go away. Sometimes this waiting may lead to a
+      deadlock, with the following results:
+      1) If a deadlock is entirely within MDL subsystem, it is
+         detected by the deadlock detector of this subsystem.
+         ER_LOCK_DEADLOCK error is produced. Then, the error handler
+         that is installed prior to the call to acquire_lock() attempts
+         to request a back-off and retry. Upon success, ER_LOCK_DEADLOCK
+         error is suppressed, otherwise propagated up the calling stack.
+      2) Otherwise, a deadlock may occur when the wait-for graph
+         includes edges not visible to the MDL deadlock detector.
+         One such example is a wait on an InnoDB row lock, e.g. when:
+         conn C1 gets SR MDL lock on t1 with SELECT * FROM t1
+         conn C2 gets a row lock on t2 with  SELECT * FROM t2 FOR UPDATE
+         conn C3 gets in and waits on C1 with DROP TABLE t0, t1
+         conn C2 continues and blocks on C3 with SELECT * FROM t0
+         conn C1 deadlocks by waiting on C2 by issuing SELECT * FROM
+         t2 LOCK IN SHARE MODE.
+         Such circular waits are currently only resolved by timeouts,
+         e.g. @@innodb_lock_wait_timeout or @@lock_wait_timeout.
+    */
+    MDL_deadlock_handler mdl_deadlock_handler(ot_ctx);
+
+    thd->push_internal_handler(&mdl_deadlock_handler);
+    bool result= thd->mdl_context.acquire_lock(mdl_request,
+                                               ot_ctx->get_timeout());
+    thd->pop_internal_handler();
+
+    if (result && !ot_ctx->can_recover_from_failed_open())
+      return TRUE;
+  }
+  *mdl_ticket= mdl_request->ticket;
+  return FALSE;
+}
+
+#ifdef WITH_PARTITION_STORAGE_ENGINE
+/* Set all [named] partitions as used. */
+static int set_partitions_as_used(TABLE_LIST *tl, TABLE *t)
+{
+  if (t->part_info)
+    return t->file->change_partitions_to_open(tl->partition_names);
+  return 0;
+}
+#endif
+
+
+/**
+  Check if the given table is actually a VIEW that was LOCK-ed
+
+  @param thd            Thread context.
+  @param t              Table to check.
+
+  @retval TRUE  The 't'-table is a locked view
+                needed to remedy problem before retrying again.
+  @retval FALSE 't' was not locked, not a VIEW or an error happened.
+*/
+
+bool is_locked_view(THD *thd, TABLE_LIST *t)
+{
+  DBUG_ENTER("is_locked_view");
+  /*
+   Is this table a view and not a base table?
+   (it is work around to allow to open view with locked tables,
+   real fix will be made after definition cache will be made)
+
+   Since opening of view which was not explicitly locked by LOCK
+   TABLES breaks metadata locking protocol (potentially can lead
+   to deadlocks) it should be disallowed.
+  */
+  if (thd->mdl_context.is_lock_owner(MDL_key::TABLE, t->db.str,
+                                     t->table_name.str, MDL_SHARED))
+  {
+    char path[FN_REFLEN + 1];
+    build_table_filename(path, sizeof(path) - 1,
+                         t->db.str, t->table_name.str, reg_ext, 0);
+    /*
+      Note that we can't be 100% sure that it is a view since it's
+      possible that we either simply have not found unused TABLE
+      instance in THD::open_tables list or were unable to open table
+      during prelocking process (in this case in theory we still
+      should hold shared metadata lock on it).
+    */
+    if (dd_frm_is_view(thd, path))
+    {
+      /*
+        If parent_l of the table_list is non null then a merge table
+        has this view as child table, which is not supported.
+      */
+      if (t->parent_l)
+      {
+        my_error(ER_WRONG_MRG_TABLE, MYF(0));
+        DBUG_RETURN(FALSE);
+      }
+
+      if (!tdc_open_view(thd, t, CHECK_METADATA_VERSION))
+      {
+        DBUG_ASSERT(t->view != 0);
+        DBUG_RETURN(TRUE); // VIEW
+      }
+    }
+  }
+
+  DBUG_RETURN(FALSE);
+}
+
+
+/**
+  Open a base table.
+
+  @param thd            Thread context.
+  @param table_list     Open first table in list.
+  @param ot_ctx         Context with flags which modify how open works
+                        and which is used to recover from a failed
+                        open_table() attempt.
+                        Some examples of flags:
+                        MYSQL_OPEN_IGNORE_FLUSH - Open table even if
+                        someone has done a flush. No version number
+                        checking is done.
+                        MYSQL_OPEN_HAS_MDL_LOCK - instead of acquiring
+                        metadata locks rely on that caller already has
+                        appropriate ones.
+
+  Uses a cache of open tables to find a TABLE instance not in use.
+
+  If TABLE_LIST::open_strategy is set to OPEN_IF_EXISTS, the table is
+  opened only if it exists. If the open strategy is OPEN_STUB, the
+  underlying table is never opened. In both cases, metadata locks are
+  always taken according to the lock strategy.
+
+  The function used to open temporary tables, but now it opens base tables
+  only.
+
+  @retval TRUE  Open failed. "action" parameter may contain type of action
+                needed to remedy problem before retrying again.
+  @retval FALSE Success. Members of TABLE_LIST structure are filled properly
+                (e.g.  TABLE_LIST::table is set for real tables and
+                TABLE_LIST::view is set for views).
+*/
+
+bool open_table(THD *thd, TABLE_LIST *table_list, Open_table_context *ot_ctx)
+{
+  TABLE *table;
+  const char *key;
+  uint	key_length;
+  const char *alias= table_list->alias.str;
+  uint flags= ot_ctx->get_flags();
+  MDL_ticket *mdl_ticket;
+  TABLE_SHARE *share;
+  uint gts_flags;
+#ifdef WITH_PARTITION_STORAGE_ENGINE
+  int part_names_error=0;
+#endif
+  DBUG_ENTER("open_table");
+
+  /*
+    The table must not be opened already. The table can be pre-opened for
+    some statements if it is a temporary table.
+
+    open_temporary_table() must be used to open temporary tables.
+  */
+  DBUG_ASSERT(!table_list->table);
+
+  /* an open table operation needs a lot of the stack space */
+  if (check_stack_overrun(thd, STACK_MIN_SIZE_FOR_OPEN, (uchar *)&alias))
+    DBUG_RETURN(TRUE);
+
+  if (!(flags & MYSQL_OPEN_IGNORE_KILLED) && thd->killed)
+  {
+    thd->send_kill_message();
+    DBUG_RETURN(TRUE);
+  }
+
+  /*
+    Check if we're trying to take a write lock in a read only transaction.
+
+    Note that we allow write locks on log tables as otherwise logging
+    to general/slow log would be disabled in read only transactions.
+  */
+  if (table_list->mdl_request.is_write_lock_request() &&
+      thd->tx_read_only &&
+      !(flags & (MYSQL_LOCK_LOG_TABLE | MYSQL_OPEN_HAS_MDL_LOCK)))
+  {
+    my_error(ER_CANT_EXECUTE_IN_READ_ONLY_TRANSACTION, MYF(0));
+    DBUG_RETURN(true);
+  }
+
+  if (!table_list->db.str)
+  {
+    my_error(ER_NO_DB_ERROR, MYF(0));
+    DBUG_RETURN(true);
+  }
+
+  key_length= get_table_def_key(table_list, &key);
+
+  /*
+    If we're in pre-locked or LOCK TABLES mode, let's try to find the
+    requested table in the list of pre-opened and locked tables. If the
+    table is not there, return an error - we can't open not pre-opened
+    tables in pre-locked/LOCK TABLES mode.
+    TODO: move this block into a separate function.
+  */
+  if (thd->locked_tables_mode &&
+      ! (flags & MYSQL_OPEN_GET_NEW_TABLE))
+  {						// Using table locks
+    TABLE *best_table= 0;
+    int best_distance= INT_MIN;
+    for (table=thd->open_tables; table ; table=table->next)
+    {
+      if (table->s->table_cache_key.length == key_length &&
+	  !memcmp(table->s->table_cache_key.str, key, key_length))
+      {
+        if (!my_strcasecmp(system_charset_info, table->alias.c_ptr(), alias) &&
+            table->query_id != thd->query_id && /* skip tables already used */
+            (thd->locked_tables_mode == LTM_LOCK_TABLES ||
+             table->query_id == 0))
+        {
+          int distance= ((int) table->reginfo.lock_type -
+                         (int) table_list->lock_type);
+
+          /*
+            Find a table that either has the exact lock type requested,
+            or has the best suitable lock. In case there is no locked
+            table that has an equal or higher lock than requested,
+            we us the closest matching lock to be able to produce an error
+            message about wrong lock mode on the table. The best_table
+            is changed if bd < 0 <= d or bd < d < 0 or 0 <= d < bd.
+
+            distance <  0 - No suitable lock found
+            distance >  0 - we have lock mode higher then we require
+            distance == 0 - we have lock mode exactly which we need
+          */
+          if ((best_distance < 0 && distance > best_distance) ||
+              (distance >= 0 && distance < best_distance))
+          {
+            best_distance= distance;
+            best_table= table;
+            if (best_distance == 0)
+            {
+              /*
+                We have found a perfect match and can finish iterating
+                through open tables list. Check for table use conflict
+                between calling statement and SP/trigger is done in
+                lock_tables().
+              */
+              break;
+            }
+          }
+        }
+      }
+    }
+    if (best_table)
+    {
+      table= best_table;
+      table->query_id= thd->query_id;
+      table->init(thd, table_list);
+      DBUG_PRINT("info",("Using locked table"));
+#ifdef WITH_PARTITION_STORAGE_ENGINE
+      part_names_error= set_partitions_as_used(table_list, table);
+#endif
+      goto reset;
+    }
+
+    if (is_locked_view(thd, table_list))
+    {
+      if (table_list->sequence)
+      {
+        my_error(ER_NOT_SEQUENCE, MYF(0), table_list->db.str, table_list->alias.str);
+        DBUG_RETURN(true);
+      }
+      DBUG_RETURN(FALSE); // VIEW
+    }
+
+    /*
+      No table in the locked tables list. In case of explicit LOCK TABLES
+      this can happen if a user did not include the table into the list.
+      In case of pre-locked mode locked tables list is generated automatically,
+      so we may only end up here if the table did not exist when
+      locked tables list was created.
+    */
+    if (thd->locked_tables_mode == LTM_PRELOCKED)
+      my_error(ER_NO_SUCH_TABLE, MYF(0), table_list->db.str, table_list->alias.str);
+    else
+      my_error(ER_TABLE_NOT_LOCKED, MYF(0), alias);
+    DBUG_RETURN(TRUE);
+  }
+
+  /*
+    Non pre-locked/LOCK TABLES mode, and the table is not temporary.
+    This is the normal use case.
+  */
+
+  if (! (flags & MYSQL_OPEN_HAS_MDL_LOCK))
+  {
+    if (open_table_get_mdl_lock(thd, ot_ctx, &table_list->mdl_request,
+                                flags, &mdl_ticket) ||
+        mdl_ticket == NULL)
+    {
+      DEBUG_SYNC(thd, "before_open_table_wait_refresh");
+      DBUG_RETURN(TRUE);
+    }
+    DEBUG_SYNC(thd, "after_open_table_mdl_shared");
+  }
+  else
+  {
+    /*
+      Grab reference to the MDL lock ticket that was acquired
+      by the caller.
+    */
+    mdl_ticket= table_list->mdl_request.ticket;
+  }
+
+  if (table_list->open_strategy == TABLE_LIST::OPEN_IF_EXISTS)
+  {
+    if (!ha_table_exists(thd, &table_list->db, &table_list->table_name))
+      DBUG_RETURN(FALSE);
+  }
+  else if (table_list->open_strategy == TABLE_LIST::OPEN_STUB)
+    DBUG_RETURN(FALSE);
+
+  /* Table exists. Let us try to open it. */
+
+  if (table_list->i_s_requested_object & OPEN_TABLE_ONLY)
+    gts_flags= GTS_TABLE;
+  else if (table_list->i_s_requested_object &  OPEN_VIEW_ONLY)
+    gts_flags= GTS_VIEW;
+  else
+    gts_flags= GTS_TABLE | GTS_VIEW;
+
+retry_share:
+
+  share= tdc_acquire_share(thd, table_list, gts_flags, &table);
+
+  if (unlikely(!share))
+  {
+    /*
+      Hide "Table doesn't exist" errors if the table belongs to a view.
+      The check for thd->is_error() is necessary to not push an
+      unwanted error in case the error was already silenced.
+      @todo Rework the alternative ways to deal with ER_NO_SUCH TABLE.
+    */
+    if (thd->is_error())
+    {
+      if (table_list->parent_l)
+      {
+        thd->clear_error();
+        my_error(ER_WRONG_MRG_TABLE, MYF(0));
+      }
+      else if (table_list->belong_to_view)
+      {
+        TABLE_LIST *view= table_list->belong_to_view;
+        thd->clear_error();
+        my_error(ER_VIEW_INVALID, MYF(0),
+                 view->view_db.str, view->view_name.str);
+      }
+    }
+    DBUG_RETURN(TRUE);
+  }
+
+  /*
+    Check if this TABLE_SHARE-object corresponds to a view. Note, that there is
+    no need to check TABLE_SHARE::tdc.flushed as we do for regular tables,
+    because view shares are always up to date.
+  */
+  if (share->is_view)
+  {
+    /*
+      If parent_l of the table_list is non null then a merge table
+      has this view as child table, which is not supported.
+    */
+    if (table_list->parent_l)
+    {
+      my_error(ER_WRONG_MRG_TABLE, MYF(0));
+      goto err_lock;
+    }
+    if (table_list->sequence)
+    {
+      my_error(ER_NOT_SEQUENCE, MYF(0), table_list->db.str,
+               table_list->alias.str);
+      goto err_lock;
+    }
+    /*
+      This table is a view. Validate its metadata version: in particular,
+      that it was a view when the statement was prepared.
+    */
+    if (check_and_update_table_version(thd, table_list, share))
+      goto err_lock;
+
+    /* Open view */
+    if (mysql_make_view(thd, share, table_list, false))
+      goto err_lock;
+
+    /* TODO: Don't free this */
+    tdc_release_share(share);
+
+    DBUG_ASSERT(table_list->view);
+
+    DBUG_RETURN(FALSE);
+  }
+
+#ifdef WITH_WSREP
+  if (!((flags & MYSQL_OPEN_IGNORE_FLUSH) ||
+        (thd->wsrep_applier)))
+#else
+  if (!(flags & MYSQL_OPEN_IGNORE_FLUSH))
+#endif
+  {
+    if (share->tdc->flushed)
+    {
+      /*
+        We already have an MDL lock. But we have encountered an old
+        version of table in the table definition cache which is possible
+        when someone changes the table version directly in the cache
+        without acquiring a metadata lock (e.g. this can happen during
+        "rolling" FLUSH TABLE(S)).
+        Release our reference to share, wait until old version of
+        share goes away and then try to get new version of table share.
+      */
+      if (table)
+        tc_release_table(table);
+      else
+        tdc_release_share(share);
+
+      MDL_deadlock_handler mdl_deadlock_handler(ot_ctx);
+      bool wait_result;
+
+      thd->push_internal_handler(&mdl_deadlock_handler);
+      wait_result= tdc_wait_for_old_version(thd, table_list->db.str,
+                                            table_list->table_name.str,
+                                            ot_ctx->get_timeout(),
+                                            mdl_ticket->get_deadlock_weight());
+      thd->pop_internal_handler();
+
+      if (wait_result)
+        DBUG_RETURN(TRUE);
+
+      goto retry_share;
+    }
+
+    if (thd->open_tables && thd->open_tables->s->tdc->flushed)
+    {
+      /*
+        If the version changes while we're opening the tables,
+        we have to back off, close all the tables opened-so-far,
+        and try to reopen them. Note: refresh_version is currently
+        changed only during FLUSH TABLES.
+      */
+      if (table)
+        tc_release_table(table);
+      else
+        tdc_release_share(share);
+      (void)ot_ctx->request_backoff_action(Open_table_context::OT_REOPEN_TABLES,
+                                           NULL);
+      DBUG_RETURN(TRUE);
+    }
+  }
+
+  if (table)
+  {
+    DBUG_ASSERT(table->file != NULL);
+    if (table->file->discover_check_version())
+    {
+      tc_release_table(table);
+      (void) ot_ctx->request_backoff_action(Open_table_context::OT_DISCOVER,
+                                            table_list);
+      DBUG_RETURN(TRUE);
+    }
+    table->file->rebind_psi();
+#ifdef WITH_PARTITION_STORAGE_ENGINE
+    part_names_error= set_partitions_as_used(table_list, table);
+#endif
+  }
+  else
+  {
+    enum open_frm_error error;
+    /* make a new table */
+    if (!(table=(TABLE*) my_malloc(key_memory_TABLE, sizeof(*table),
+                                   MYF(MY_WME))))
+      goto err_lock;
+
+    error= open_table_from_share(thd, share, &table_list->alias,
+                                 HA_OPEN_KEYFILE | HA_TRY_READ_ONLY,
+                                 EXTRA_RECORD,
+                                 thd->open_options, table, FALSE,
+                                 IF_PARTITIONING(table_list->partition_names,0));
+
+    if (unlikely(error))
+    {
+      my_free(table);
+
+      if (error == OPEN_FRM_DISCOVER)
+        (void) ot_ctx->request_backoff_action(Open_table_context::OT_DISCOVER,
+                                              table_list);
+      else if (share->crashed)
+      {
+        if (!(flags & MYSQL_OPEN_IGNORE_REPAIR))
+          (void) ot_ctx->request_backoff_action(Open_table_context::OT_REPAIR,
+                                                table_list);
+        else
+          table_list->crashed= 1;  /* Mark that table was crashed */
+      }
+      goto err_lock;
+    }
+    if (open_table_entry_fini(thd, share, table))
+    {
+      closefrm(table);
+      my_free(table);
+      goto err_lock;
+    }
+
+    /* Add table to the share's used tables list. */
+    tc_add_table(thd, table);
+  }
+
+  if (!(flags & MYSQL_OPEN_HAS_MDL_LOCK) &&
+      table->s->table_category < TABLE_CATEGORY_INFORMATION)
+  {
+    /*
+      We are not under LOCK TABLES and going to acquire write-lock/
+      modify the base table. We need to acquire protection against
+      global read lock until end of this statement in order to have
+      this statement blocked by active FLUSH TABLES WITH READ LOCK.
+
+      We don't need to acquire this protection under LOCK TABLES as
+      such protection already acquired at LOCK TABLES time and
+      not released until UNLOCK TABLES.
+
+      We don't block statements which modify only temporary tables
+      as these tables are not preserved by any form of
+      backup which uses FLUSH TABLES WITH READ LOCK.
+
+      TODO: The fact that we sometimes acquire protection against
+            GRL only when we encounter table to be write-locked
+            slightly increases probability of deadlock.
+            This problem will be solved once Alik pushes his
+            temporary table refactoring patch and we can start
+            pre-acquiring metadata locks at the beggining of
+            open_tables() call.
+    */
+    enum enum_mdl_type mdl_type= MDL_BACKUP_DML;
+
+    if (table->s->table_category != TABLE_CATEGORY_USER)
+      mdl_type= MDL_BACKUP_SYS_DML;
+    else if (table->s->online_backup)
+      mdl_type= MDL_BACKUP_TRANS_DML;
+
+    if (table_list->mdl_request.is_write_lock_request() &&
+        ! (flags & (MYSQL_OPEN_IGNORE_GLOBAL_READ_LOCK |
+                    MYSQL_OPEN_FORCE_SHARED_MDL |
+                    MYSQL_OPEN_FORCE_SHARED_HIGH_PRIO_MDL |
+                    MYSQL_OPEN_SKIP_SCOPED_MDL_LOCK)) &&
+        ! ot_ctx->has_protection_against_grl(mdl_type))
+    {
+      MDL_request protection_request;
+      MDL_deadlock_handler mdl_deadlock_handler(ot_ctx);
+
+      if (thd->has_read_only_protection())
+      {
+        MYSQL_UNBIND_TABLE(table->file);
+        tc_release_table(table);
+        DBUG_RETURN(TRUE);
+      }
+
+      MDL_REQUEST_INIT(&protection_request, MDL_key::BACKUP, "", "", mdl_type,
+                       MDL_STATEMENT);
+
+      /*
+        Install error handler which if possible will convert deadlock error
+        into request to back-off and restart process of opening tables.
+      */
+      thd->push_internal_handler(&mdl_deadlock_handler);
+      bool result= thd->mdl_context.acquire_lock(&protection_request,
+                                                 ot_ctx->get_timeout());
+      thd->pop_internal_handler();
+
+      if (result)
+      {
+        MYSQL_UNBIND_TABLE(table->file);
+        tc_release_table(table);
+        DBUG_RETURN(TRUE);
+      }
+
+      ot_ctx->set_has_protection_against_grl(mdl_type);
+    }
+  }
+
+  table->mdl_ticket= mdl_ticket;
+  table->reginfo.lock_type=TL_READ;		/* Assume read */
+
+  table->init(thd, table_list);
+
+  table->next= thd->open_tables;		/* Link into simple list */
+  thd->set_open_tables(table);
+
+ reset:
+  /*
+    Check that there is no reference to a condition from an earlier query
+    (cf. Bug#58553). 
+  */
+  DBUG_ASSERT(table->file->pushed_cond == NULL);
+  table_list->updatable= 1; // It is not derived table nor non-updatable VIEW
+  table_list->table= table;
+
+#ifdef WITH_PARTITION_STORAGE_ENGINE
+  if (unlikely(table->part_info))
+  {
+    /* Partitions specified were incorrect.*/
+    if (part_names_error)
+    {
+      table->file->print_error(part_names_error, MYF(0));
+      DBUG_RETURN(true);
+    }
+  }
+  else if (table_list->partition_names)
+  {
+    /* Don't allow PARTITION () clause on a nonpartitioned table */
+    my_error(ER_PARTITION_CLAUSE_ON_NONPARTITIONED, MYF(0));
+    DBUG_RETURN(true);
+  }
+#endif
+  if (table_list->sequence && table->s->table_type != TABLE_TYPE_SEQUENCE)
+  {
+    my_error(ER_NOT_SEQUENCE, MYF(0), table_list->db.str, table_list->alias.str);
+    DBUG_RETURN(true);
+  }
+
+  DBUG_ASSERT(thd->locked_tables_mode || table->file->row_logging == 0);
+  DBUG_RETURN(false);
+
+err_lock:
+  tdc_release_share(share);
+
+  DBUG_PRINT("exit", ("failed"));
+  DBUG_RETURN(true);
+}
+
+
+/**
+   Find table in the list of open tables.
+
+   @param list       List of TABLE objects to be inspected.
+   @param db         Database name
+   @param table_name Table name
+
+   @return Pointer to the TABLE object found, 0 if no table found.
+*/
+
+TABLE *find_locked_table(TABLE *list, const char *db, const char *table_name)
+{
+  char	key[MAX_DBKEY_LENGTH];
+  uint key_length= tdc_create_key(key, db, table_name);
+
+  for (TABLE *table= list; table ; table=table->next)
+  {
+    if (table->s->table_cache_key.length == key_length &&
+	!memcmp(table->s->table_cache_key.str, key, key_length))
+      return table;
+  }
+  return(0);
+}
+
+
+/**
+   Find instance of TABLE with upgradable or exclusive metadata
+   lock from the list of open tables, emit error if no such table
+   found.
+
+   @param thd        Thread context
+   @param db         Database name.
+   @param table_name Name of table.
+   @param p_error    In the case of an error (when the function returns NULL)
+                     the error number is stored there.
+                     If the p_error is NULL, function launches the error itself.
+
+   @note This function checks if the connection holds a global IX
+         metadata lock. If no such lock is found, it is not safe to
+         upgrade the lock and ER_TABLE_NOT_LOCKED_FOR_WRITE will be
+         reported.
+
+   @return Pointer to TABLE instance with MDL_SHARED_UPGRADABLE
+           MDL_SHARED_NO_WRITE, MDL_SHARED_NO_READ_WRITE, or
+           MDL_EXCLUSIVE metadata lock, NULL otherwise.
+*/
+
+TABLE *find_table_for_mdl_upgrade(THD *thd, const char *db,
+                                  const char *table_name, int *p_error)
+{
+  TABLE *tab= find_locked_table(thd->open_tables, db, table_name);
+  int error;
+
+  if (unlikely(!tab))
+  {
+    error= ER_TABLE_NOT_LOCKED;
+    goto err_exit;
+  }
+
+  /*
+    It is not safe to upgrade the metadata lock without a global IX lock.
+    This can happen with FLUSH TABLES <list> WITH READ LOCK as we in these
+    cases don't take a global IX lock in order to be compatible with
+    global read lock.
+  */
+  if (unlikely(!thd->mdl_context.is_lock_owner(MDL_key::BACKUP, "", "",
+                                               MDL_BACKUP_DDL)))
+  {
+    error= ER_TABLE_NOT_LOCKED_FOR_WRITE;
+    goto err_exit;
+  }
+
+  while (tab->mdl_ticket != NULL &&
+         !tab->mdl_ticket->is_upgradable_or_exclusive() &&
+         (tab= find_locked_table(tab->next, db, table_name)))
+    continue;
+
+  if (unlikely(!tab))
+  {
+    error= ER_TABLE_NOT_LOCKED_FOR_WRITE;
+    goto err_exit;
+  }
+
+  return tab;
+
+err_exit:
+  if (p_error)
+    *p_error= error;
+  else
+    my_error(error, MYF(0), table_name);
+
+  return NULL;
+}
+
+
+/***********************************************************************
+  class Locked_tables_list implementation. Declared in sql_class.h
+************************************************************************/
+
+/**
+  Enter LTM_LOCK_TABLES mode.
+
+  Enter the LOCK TABLES mode using all the tables that are
+  currently open and locked in this connection.
+  Initializes a TABLE_LIST instance for every locked table.
+
+  @param  thd  thread handle
+
+  @return TRUE if out of memory.
+*/
+
+bool
+Locked_tables_list::init_locked_tables(THD *thd)
+{
+  DBUG_ASSERT(thd->locked_tables_mode == LTM_NONE);
+  DBUG_ASSERT(m_locked_tables == NULL);
+  DBUG_ASSERT(m_reopen_array == NULL);
+  DBUG_ASSERT(m_locked_tables_count == 0);
+
+  for (TABLE *table= thd->open_tables; table;
+       table= table->next, m_locked_tables_count++)
+  {
+    TABLE_LIST *src_table_list= table->pos_in_table_list;
+    LEX_CSTRING db, table_name, alias;
+
+    db.length=         table->s->db.length;
+    table_name.length= table->s->table_name.length;
+    alias.length=      table->alias.length();
+    TABLE_LIST *dst_table_list;
+
+    if (! multi_alloc_root(&m_locked_tables_root,
+                           &dst_table_list, sizeof(*dst_table_list),
+                           &db.str, (size_t) db.length + 1,
+                           &table_name.str, (size_t) table_name.length + 1,
+                           &alias.str, (size_t) alias.length + 1,
+                           NullS))
+    {
+      reset();
+      return TRUE;
+    }
+
+    memcpy((char*) db.str,         table->s->db.str, db.length + 1);
+    memcpy((char*) table_name.str, table->s->table_name.str,
+           table_name.length + 1);
+    memcpy((char*) alias.str,      table->alias.c_ptr(), alias.length + 1);
+    dst_table_list->init_one_table(&db, &table_name,
+                                   &alias, table->reginfo.lock_type);
+    dst_table_list->table= table;
+    dst_table_list->mdl_request.ticket= src_table_list->mdl_request.ticket;
+
+    /* Link last into the list of tables */
+    *(dst_table_list->prev_global= m_locked_tables_last)= dst_table_list;
+    m_locked_tables_last= &dst_table_list->next_global;
+    table->pos_in_locked_tables= dst_table_list;
+  }
+  if (m_locked_tables_count)
+  {
+    /**
+      Allocate an auxiliary array to pass to mysql_lock_tables()
+      in reopen_tables(). reopen_tables() is a critical
+      path and we don't want to complicate it with extra allocations.
+    */
+    m_reopen_array= (TABLE_LIST**)alloc_root(&m_locked_tables_root,
+                                             sizeof(TABLE_LIST*) *
+                                             (m_locked_tables_count+1));
+    if (m_reopen_array == NULL)
+    {
+      reset();
+      return TRUE;
+    }
+  }
+
+  TRANSACT_TRACKER(add_trx_state(thd, TX_LOCKED_TABLES));
+
+  thd->enter_locked_tables_mode(LTM_LOCK_TABLES);
+
+  return FALSE;
+}
+
+
+/**
+  Leave LTM_LOCK_TABLES mode if it's been entered.
+
+  Close all locked tables, free memory, and leave the mode.
+
+  @note This function is a no-op if we're not in LOCK TABLES.
+*/
+
+int
+Locked_tables_list::unlock_locked_tables(THD *thd)
+{
+  int error;
+  DBUG_ASSERT(!thd->in_sub_stmt &&
+              !(thd->state_flags & Open_tables_state::BACKUPS_AVAIL));
+  /*
+    Sic: we must be careful to not close open tables if
+    we're not in LOCK TABLES mode: unlock_locked_tables() is
+    sometimes called implicitly, expecting no effect on
+    open tables, e.g. from begin_trans().
+  */
+  if (thd->locked_tables_mode != LTM_LOCK_TABLES)
+    return 0;
+
+  for (TABLE_LIST *table_list= m_locked_tables;
+       table_list; table_list= table_list->next_global)
+  {
+    /*
+      Clear the position in the list, the TABLE object will be
+      returned to the table cache.
+    */
+    if (table_list->table)                    // If not closed
+      table_list->table->pos_in_locked_tables= NULL;
+  }
+  thd->leave_locked_tables_mode();
+
+  TRANSACT_TRACKER(clear_trx_state(thd, TX_LOCKED_TABLES));
+
+  DBUG_ASSERT(thd->transaction->stmt.is_empty());
+  error= close_thread_tables(thd);
+
+  /*
+    We rely on the caller to implicitly commit the
+    transaction and release transactional locks.
+  */
+
+  /*
+    After closing tables we can free memory used for storing lock
+    request for metadata locks and TABLE_LIST elements.
+  */
+  reset();
+  return error;
+}
+
+
+/**
+  Remove all meta data locks associated with table and release locked
+  table mode if there is no locked tables anymore
+*/
+
+int
+Locked_tables_list::unlock_locked_table(THD *thd, MDL_ticket *mdl_ticket)
+{
+  /*
+    Ensure we are in locked table mode.
+    As this function is only called on error condition it's better
+    to check this condition here than in the caller.
+  */
+  if (thd->locked_tables_mode != LTM_LOCK_TABLES)
+    return 0;
+
+  if (mdl_ticket)
+  {
+    /*
+      Under LOCK TABLES we may have several instances of table open
+      and locked and therefore have to remove several metadata lock
+      requests associated with them.
+    */
+    thd->mdl_context.release_all_locks_for_name(mdl_ticket);
+  }
+
+  if (thd->lock->table_count == 0)
+    return unlock_locked_tables(thd);
+  return 0;
+}
+
+
+/*
+  Free memory allocated for storing locks
+*/
+
+void Locked_tables_list::reset()
+{
+  free_root(&m_locked_tables_root, MYF(0));
+  m_locked_tables= NULL;
+  m_locked_tables_last= &m_locked_tables;
+  m_reopen_array= NULL;
+  m_locked_tables_count= 0;
+  some_table_marked_for_reopen= 0;
+}
+
+
+/**
+  Unlink a locked table from the locked tables list, either
+  temporarily or permanently.
+
+  @param  thd        thread handle
+  @param  table_list the element of locked tables list.
+                     The implementation assumes that this argument
+                     points to a TABLE_LIST element linked into
+                     the locked tables list. Passing a TABLE_LIST
+                     instance that is not part of locked tables
+                     list will lead to a crash.
+  @param  remove_from_locked_tables
+                      TRUE if the table is removed from the list
+                      permanently.
+
+  This function is a no-op if we're not under LOCK TABLES.
+
+  @sa Locked_tables_list::reopen_tables()
+*/
+
+
+void Locked_tables_list::unlink_from_list(THD *thd,
+                                          TABLE_LIST *table_list,
+                                          bool remove_from_locked_tables)
+{
+  /*
+    If mode is not LTM_LOCK_TABLES, we needn't do anything. Moreover,
+    outside this mode pos_in_locked_tables value is not trustworthy.
+  */
+  if (thd->locked_tables_mode != LTM_LOCK_TABLES &&
+      thd->locked_tables_mode != LTM_PRELOCKED_UNDER_LOCK_TABLES)
+    return;
+
+  /*
+    table_list must be set and point to pos_in_locked_tables of some
+    table.
+  */
+  DBUG_ASSERT(table_list->table->pos_in_locked_tables == table_list);
+
+  /* Clear the pointer, the table will be returned to the table cache. */
+  table_list->table->pos_in_locked_tables= NULL;
+
+  /* Mark the table as closed in the locked tables list. */
+  table_list->table= NULL;
+
+  /*
+    If the table is being dropped or renamed, remove it from
+    the locked tables list (implicitly drop the LOCK TABLES lock
+    on it).
+  */
+  if (remove_from_locked_tables)
+  {
+    *table_list->prev_global= table_list->next_global;
+    if (table_list->next_global == NULL)
+      m_locked_tables_last= table_list->prev_global;
+    else
+      table_list->next_global->prev_global= table_list->prev_global;
+    m_locked_tables_count--;
+  }
+}
+
+/**
+  This is an attempt to recover (somewhat) in case of an error.
+  If we failed to reopen a closed table, let's unlink it from the
+  list and forget about it. From a user perspective that would look
+  as if the server "lost" the lock on one of the locked tables.
+
+  @note This function is a no-op if we're not under LOCK TABLES.
+*/
+
+void Locked_tables_list::
+unlink_all_closed_tables(THD *thd, MYSQL_LOCK *lock, size_t reopen_count)
+{
+  /* If we managed to take a lock, unlock tables and free the lock. */
+  if (lock)
+    mysql_unlock_tables(thd, lock);
+  /*
+    If a failure happened in reopen_tables(), we may have succeeded
+    reopening some tables, but not all.
+    This works when the connection was killed in mysql_lock_tables().
+  */
+  if (reopen_count)
+  {
+    while (reopen_count--)
+    {
+      /*
+        When closing the table, we must remove it
+        from thd->open_tables list.
+        We rely on the fact that open_table() that was used
+        in reopen_tables() always links the opened table
+        to the beginning of the open_tables list.
+      */
+      DBUG_ASSERT(thd->open_tables == m_reopen_array[reopen_count]->table);
+
+      thd->open_tables->pos_in_locked_tables->table= NULL;
+      thd->open_tables->pos_in_locked_tables= NULL;
+
+      close_thread_table(thd, &thd->open_tables);
+    }
+  }
+  /* Exclude all closed tables from the LOCK TABLES list. */
+  for (TABLE_LIST *table_list= m_locked_tables; table_list; table_list=
+       table_list->next_global)
+  {
+    if (table_list->table == NULL)
+    {
+      /* Unlink from list. */
+      *table_list->prev_global= table_list->next_global;
+      if (table_list->next_global == NULL)
+        m_locked_tables_last= table_list->prev_global;
+      else
+        table_list->next_global->prev_global= table_list->prev_global;
+      m_locked_tables_count--;
+    }
+  }
+
+  /* If no tables left, do an automatic UNLOCK TABLES */
+  if (thd->lock && thd->lock->table_count == 0)
+  {
+    /*
+      We have to rollback any open transactions here.
+      This is required in the case where the server has been killed
+      but some transations are still open (as part of locked tables).
+      If we don't do this, we will get an assert in unlock_locked_tables().
+    */
+    ha_rollback_trans(thd, FALSE);
+    ha_rollback_trans(thd, TRUE);
+    unlock_locked_tables(thd);
+  }
+}
+
+
+/*
+  Mark all instances of the table to be reopened
+
+  This is only needed when LOCK TABLES is active
+*/
+
+void Locked_tables_list::mark_table_for_reopen(THD *thd, TABLE *table)
+{
+  TABLE_SHARE *share= table->s;
+
+    for (TABLE_LIST *table_list= m_locked_tables;
+       table_list; table_list= table_list->next_global)
+  {
+    if (table_list->table->s == share)
+      table_list->table->internal_set_needs_reopen(true);
+  }
+  /* This is needed in the case where lock tables where not used */
+  table->internal_set_needs_reopen(true);
+  some_table_marked_for_reopen= 1;
+}
+
+
+/**
+  Reopen the tables locked with LOCK TABLES and temporarily closed
+  by a DDL statement or FLUSH TABLES.
+
+  @param need_reopen  If set, reopen open tables that are marked with
+                      for reopen.
+                      If not set, reopen tables that where closed.
+
+  @note This function is a no-op if we're not under LOCK TABLES.
+
+  @return TRUE if an error reopening the tables. May happen in
+               case of some fatal system error only, e.g. a disk
+               corruption, out of memory or a serious bug in the
+               locking.
+*/
+
+bool
+Locked_tables_list::reopen_tables(THD *thd, bool need_reopen)
+{
+  Open_table_context ot_ctx(thd, MYSQL_OPEN_REOPEN);
+  uint reopen_count= 0;
+  MYSQL_LOCK *lock;
+  MYSQL_LOCK *merged_lock;
+  DBUG_ENTER("Locked_tables_list::reopen_tables");
+
+  DBUG_ASSERT(some_table_marked_for_reopen || !need_reopen);
+
+
+  /* Reset flag that some table was marked for reopen */
+  if (need_reopen)
+    some_table_marked_for_reopen= 0;
+
+  for (TABLE_LIST *table_list= m_locked_tables;
+       table_list; table_list= table_list->next_global)
+  {
+    if (need_reopen)
+    {
+      if (!table_list->table || !table_list->table->needs_reopen())
+        continue;
+      for (TABLE **prev= &thd->open_tables; *prev; prev= &(*prev)->next)
+      {
+        if (*prev == table_list->table)
+        {
+          thd->locked_tables_list.unlink_from_list(thd, table_list, false);
+          mysql_lock_remove(thd, thd->lock, *prev);
+          (*prev)->file->extra(HA_EXTRA_PREPARE_FOR_FORCED_CLOSE);
+          close_thread_table(thd, prev);
+          break;
+        }
+      }
+      DBUG_ASSERT(table_list->table == NULL);
+    }
+    else
+    {
+      if (table_list->table)                      /* The table was not closed */
+        continue;
+    }
+
+    DBUG_ASSERT(reopen_count < m_locked_tables_count);
+    m_reopen_array[reopen_count++]= table_list;
+  }
+  if (reopen_count)
+  {
+    TABLE **tables= (TABLE**) my_alloca(reopen_count * sizeof(TABLE*));
+
+    for (uint i= 0 ; i < reopen_count ; i++)
+    {
+      TABLE_LIST *table_list= m_reopen_array[i];
+      /* Links into thd->open_tables upon success */
+      if (open_table(thd, table_list, &ot_ctx))
+      {
+        unlink_all_closed_tables(thd, 0, i);
+        my_afree((void*) tables);
+        DBUG_RETURN(TRUE);
+      }
+      tables[i]= table_list->table;
+      table_list->table->pos_in_locked_tables= table_list;
+      /* See also the comment on lock type in init_locked_tables(). */
+      table_list->table->reginfo.lock_type= table_list->lock_type;
+    }
+
+    thd->in_lock_tables= 1;
+    /*
+      We re-lock all tables with mysql_lock_tables() at once rather
+      than locking one table at a time because of the case
+      reported in Bug#45035: when the same table is present
+      in the list many times, thr_lock.c fails to grant READ lock
+      on a table that is already locked by WRITE lock, even if
+      WRITE lock is taken by the same thread. If READ and WRITE
+      lock are passed to thr_lock.c in the same list, everything
+      works fine. Patching legacy code of thr_lock.c is risking to
+      break something else.
+    */
+    lock= mysql_lock_tables(thd, tables, reopen_count,
+                            MYSQL_OPEN_REOPEN | MYSQL_LOCK_USE_MALLOC);
+    thd->in_lock_tables= 0;
+    if (lock == NULL || (merged_lock=
+                         mysql_lock_merge(thd->lock, lock)) == NULL)
+    {
+      unlink_all_closed_tables(thd, lock, reopen_count);
+      if (! thd->killed)
+        my_error(ER_LOCK_DEADLOCK, MYF(0));
+      my_afree((void*) tables);
+      DBUG_RETURN(TRUE);
+    }
+    thd->lock= merged_lock;
+    my_afree((void*) tables);
+  }
+  DBUG_RETURN(FALSE);
+}
+
+/**
+  Add back a locked table to the locked list that we just removed from it.
+  This is needed in CREATE OR REPLACE TABLE where we are dropping, creating
+  and re-opening a locked table.
+
+  @return 0  0k
+  @return 1  error
+*/
+
+bool Locked_tables_list::restore_lock(THD *thd, TABLE_LIST *dst_table_list,
+                                      TABLE *table, MYSQL_LOCK *lock)
+{
+  MYSQL_LOCK *merged_lock;
+  DBUG_ENTER("restore_lock");
+  DBUG_ASSERT(!strcmp(dst_table_list->table_name.str, table->s->table_name.str));
+
+  /* Ensure we have the memory to add the table back */
+  if (!(merged_lock= mysql_lock_merge(thd->lock, lock)))
+    DBUG_RETURN(1);
+  thd->lock= merged_lock;
+
+  /* Link to the new table */
+  dst_table_list->table= table;
+  /*
+    The lock type may have changed (normally it should not as create
+    table will lock the table in write mode
+  */
+  dst_table_list->lock_type= table->reginfo.lock_type;
+  table->pos_in_locked_tables= dst_table_list;
+
+  add_back_last_deleted_lock(dst_table_list);
+
+  table->mdl_ticket->downgrade_lock(table->reginfo.lock_type >=
+                                    TL_WRITE_ALLOW_WRITE ? 
+                                    MDL_SHARED_NO_READ_WRITE :
+                                    MDL_SHARED_READ);
+
+  DBUG_RETURN(0);
+}
+
+/*
+  Add back the last deleted lock structure.
+  This should be followed by a call to reopen_tables() to
+  open the table.
+*/
+
+void Locked_tables_list::add_back_last_deleted_lock(TABLE_LIST *dst_table_list)
+{
+  /* Link the lock back in the locked tables list */
+  dst_table_list->prev_global= m_locked_tables_last;
+  *m_locked_tables_last= dst_table_list;
+  m_locked_tables_last= &dst_table_list->next_global;
+  dst_table_list->next_global= 0;
+  m_locked_tables_count++;
+}
+
+
+#ifndef DBUG_OFF
+/* Cause a spurious statement reprepare for debug purposes. */
+static bool inject_reprepare(THD *thd)
+{
+  if (thd->m_reprepare_observer && thd->stmt_arena->is_reprepared == FALSE)
+  {
+    thd->m_reprepare_observer->report_error(thd);
+    return TRUE;
+  }
+
+  return FALSE;
+}
+#endif
+
+/**
+  Compare metadata versions of an element obtained from the table
+  definition cache and its corresponding node in the parse tree.
+
+  @details If the new and the old values mismatch, invoke
+  Metadata_version_observer.
+  At prepared statement prepare, all TABLE_LIST version values are
+  NULL and we always have a mismatch. But there is no observer set
+  in THD, and therefore no error is reported. Instead, we update
+  the value in the parse tree, effectively recording the original
+  version.
+  At prepared statement execute, an observer may be installed.  If
+  there is a version mismatch, we push an error and return TRUE.
+
+  For conventional execution (no prepared statements), the
+  observer is never installed.
+
+  @sa Execute_observer
+  @sa check_prepared_statement() to see cases when an observer is installed
+  @sa TABLE_LIST::is_table_ref_id_equal()
+  @sa TABLE_SHARE::get_table_ref_id()
+
+  @param[in]      thd         used to report errors
+  @param[in,out]  tables      TABLE_LIST instance created by the parser
+                              Metadata version information in this object
+                              is updated upon success.
+  @param[in]      table_share an element from the table definition cache
+
+  @retval  TRUE  an error, which has been reported
+  @retval  FALSE success, version in TABLE_LIST has been updated
+*/
+
+static bool
+check_and_update_table_version(THD *thd,
+                               TABLE_LIST *tables, TABLE_SHARE *table_share)
+{
+  if (! tables->is_table_ref_id_equal(table_share))
+  {
+    if (thd->m_reprepare_observer &&
+        thd->m_reprepare_observer->report_error(thd))
+    {
+      /*
+        Version of the table share is different from the
+        previous execution of the prepared statement, and it is
+        unacceptable for this SQLCOM. Error has been reported.
+      */
+      DBUG_ASSERT(thd->is_error());
+      return TRUE;
+    }
+    /* Always maintain the latest version and type */
+    tables->set_table_ref_id(table_share);
+  }
+
+  DBUG_EXECUTE_IF("reprepare_each_statement", return inject_reprepare(thd););
+  return FALSE;
+}
+
+
+/**
+  Compares versions of a stored routine obtained from the sp cache
+  and the version used at prepare.
+
+  @details If the new and the old values mismatch, invoke
+  Metadata_version_observer.
+  At prepared statement prepare, all Sroutine_hash_entry version values
+  are NULL and we always have a mismatch. But there is no observer set
+  in THD, and therefore no error is reported. Instead, we update
+  the value in Sroutine_hash_entry, effectively recording the original
+  version.
+  At prepared statement execute, an observer may be installed.  If
+  there is a version mismatch, we push an error and return TRUE.
+
+  For conventional execution (no prepared statements), the
+  observer is never installed.
+
+  @param[in]      thd         used to report errors
+  @param[in/out]  rt          pointer to stored routine entry in the
+                              parse tree
+  @param[in]      sp          pointer to stored routine cache entry.
+                              Can be NULL if there is no such routine.
+  @retval  TRUE  an error, which has been reported
+  @retval  FALSE success, version in Sroutine_hash_entry has been updated
+*/
+
+static bool
+check_and_update_routine_version(THD *thd, Sroutine_hash_entry *rt,
+                                 sp_head *sp)
+{
+  ulong spc_version= sp_cache_version();
+  /* sp is NULL if there is no such routine. */
+  ulong version= sp ? sp->sp_cache_version() : spc_version;
+  /*
+    If the version in the parse tree is stale,
+    or the version in the cache is stale and sp is not used,
+    we need to reprepare.
+    Sic: version != spc_version <--> sp is not NULL.
+  */
+  if (rt->m_sp_cache_version != version ||
+      (version != spc_version && !sp->is_invoked()))
+  {
+    if (thd->m_reprepare_observer &&
+        thd->m_reprepare_observer->report_error(thd))
+    {
+      /*
+        Version of the sp cache is different from the
+        previous execution of the prepared statement, and it is
+        unacceptable for this SQLCOM. Error has been reported.
+      */
+      DBUG_ASSERT(thd->is_error());
+      return TRUE;
+    }
+    /* Always maintain the latest cache version. */
+    rt->m_sp_cache_version= version;
+  }
+  return FALSE;
+}
+
+
+/**
+   Open view by getting its definition from disk (and table cache in future).
+
+   @param thd               Thread handle
+   @param table_list        TABLE_LIST with db, table_name & belong_to_view
+   @param flags             Flags which modify how we open the view
+
+   @todo This function is needed for special handling of views under
+         LOCK TABLES. We probably should get rid of it in long term.
+
+   @return FALSE if success, TRUE - otherwise.
+*/
+
+bool tdc_open_view(THD *thd, TABLE_LIST *table_list, uint flags)
+{
+  TABLE not_used;
+  TABLE_SHARE *share;
+  bool err= TRUE;
+
+  if (!(share= tdc_acquire_share(thd, table_list, GTS_VIEW)))
+    return TRUE;
+
+  DBUG_ASSERT(share->is_view);
+
+  if (flags & CHECK_METADATA_VERSION)
+  {
+    /*
+      Check TABLE_SHARE-version of view only if we have been instructed to do
+      so. We do not need to check the version if we're executing CREATE VIEW or
+      ALTER VIEW statements.
+
+      In the future, this functionality should be moved out from
+      tdc_open_view(), and  tdc_open_view() should became a part of a clean
+      table-definition-cache interface.
+    */
+    if (check_and_update_table_version(thd, table_list, share))
+      goto ret;
+  }
+
+  err= mysql_make_view(thd, share, table_list, (flags & OPEN_VIEW_NO_PARSE));
+ret:
+  tdc_release_share(share);
+
+  return err;
+}
+
+
+/**
+   Finalize the process of TABLE creation by loading table triggers
+   and taking action if a HEAP table content was emptied implicitly.
+*/
+
+static bool open_table_entry_fini(THD *thd, TABLE_SHARE *share, TABLE *entry)
+{
+  if (Table_triggers_list::check_n_load(thd, &share->db,
+                                        &share->table_name, entry, 0))
+    return TRUE;
+
+  /*
+    If we are here, there was no fatal error (but error may be still
+    unitialized).
+  */
+  if (unlikely(entry->file->implicit_emptied))
+  {
+    entry->file->implicit_emptied= 0;
+    if (mysql_bin_log.is_open())
+    {
+      char query_buf[2*FN_REFLEN + 21];
+      String query(query_buf, sizeof(query_buf), system_charset_info);
+
+      query.length(0);
+      query.append("DELETE FROM ");
+      append_identifier(thd, &query, &share->db);
+      query.append(".");
+      append_identifier(thd, &query, &share->table_name);
+
+      /*
+        we bypass thd->binlog_query() here,
+        as it does a lot of extra work, that is simply wrong in this case
+      */
+      Query_log_event qinfo(thd, query.ptr(), query.length(),
+                            FALSE, TRUE, TRUE, 0);
+      if (mysql_bin_log.write(&qinfo))
+        return TRUE;
+    }
+  }
+  return FALSE;
+}
+
+
+/**
+   Auxiliary routine which is used for performing automatical table repair.
+*/
+
+static bool auto_repair_table(THD *thd, TABLE_LIST *table_list)
+{
+  TABLE_SHARE *share;
+  TABLE entry;
+  bool result= TRUE;
+
+  thd->clear_error();
+
+  if (!(share= tdc_acquire_share(thd, table_list, GTS_TABLE)))
+    return result;
+
+  DBUG_ASSERT(! share->is_view);
+
+  if (open_table_from_share(thd, share, &table_list->alias,
+                            HA_OPEN_KEYFILE | HA_TRY_READ_ONLY,
+                            EXTRA_RECORD,
+                            ha_open_options | HA_OPEN_FOR_REPAIR,
+                            &entry, FALSE) || ! entry.file ||
+      (entry.file->is_crashed() && entry.file->ha_check_and_repair(thd)))
+  {
+    /* Give right error message */
+    thd->clear_error();
+    my_error(ER_NOT_KEYFILE, MYF(0), share->table_name.str);
+    sql_print_error("Couldn't repair table: %s.%s", share->db.str,
+                    share->table_name.str);
+    if (entry.file)
+      closefrm(&entry);
+  }
+  else
+  {
+    thd->clear_error();			// Clear error message
+    closefrm(&entry);
+    result= FALSE;
+  }
+
+  tdc_remove_referenced_share(thd, share);
+  return result;
+}
+
+
+/** Open_table_context */
+
+Open_table_context::Open_table_context(THD *thd, uint flags)
+  :m_thd(thd),
+   m_failed_table(NULL),
+   m_start_of_statement_svp(thd->mdl_context.mdl_savepoint()),
+   m_timeout(flags & MYSQL_LOCK_IGNORE_TIMEOUT ?
+             LONG_TIMEOUT : thd->variables.lock_wait_timeout),
+   m_flags(flags),
+   m_action(OT_NO_ACTION),
+   m_has_locks(thd->mdl_context.has_locks()),
+   m_has_protection_against_grl(0)
+{}
+
+
+/**
+  Check if we can back-off and set back off action if we can.
+  Otherwise report and return error.
+
+  @retval  TRUE if back-off is impossible.
+  @retval  FALSE if we can back off. Back off action has been set.
+*/
+
+bool
+Open_table_context::
+request_backoff_action(enum_open_table_action action_arg,
+                       TABLE_LIST *table)
+{
+  /*
+    A back off action may be one of three kinds:
+
+    * We met a broken table that needs repair, or a table that
+      is not present on this MySQL server and needs re-discovery.
+      To perform the action, we need an exclusive metadata lock on
+      the table. Acquiring X lock while holding other shared
+      locks can easily lead to deadlocks. We rely on MDL deadlock
+      detector to discover them. If this is a multi-statement
+      transaction that holds metadata locks for completed statements,
+      we should keep these locks after discovery/repair.
+      The action type in this case is OT_DISCOVER or OT_REPAIR.
+    * Our attempt to acquire an MDL lock lead to a deadlock,
+      detected by the MDL deadlock detector. The current
+      session was chosen a victim. If this is a multi-statement
+      transaction that holds metadata locks taken by completed
+      statements, restarting locking for the current statement
+      may lead to a livelock. Releasing locks of completed
+      statements can not be done as will lead to violation
+      of ACID. Thus, again, if m_has_locks is set,
+      we report an error. Otherwise, when there are no metadata
+      locks other than which belong to this statement, we can
+      try to recover from error by releasing all locks and
+      restarting the pre-locking.
+      Similarly, a deadlock error can occur when the
+      pre-locking process met a TABLE_SHARE that is being
+      flushed, and unsuccessfully waited for the flush to
+      complete. A deadlock in this case can happen, e.g.,
+      when our session is holding a metadata lock that
+      is being waited on by a session which is using
+      the table which is being flushed. The only way
+      to recover from this error is, again, to close all
+      open tables, release all locks, and retry pre-locking.
+      Action type name is OT_REOPEN_TABLES. Re-trying
+      while holding some locks may lead to a livelock,
+      and thus we don't do it.
+    * Finally, this session has open TABLEs from different
+      "generations" of the table cache. This can happen, e.g.,
+      when, after this session has successfully opened one
+      table used for a statement, FLUSH TABLES interfered and
+      expelled another table used in it. FLUSH TABLES then
+      blocks and waits on the table already opened by this
+      statement.
+      We detect this situation by ensuring that table cache
+      version of all tables used in a statement is the same.
+      If it isn't, all tables needs to be reopened.
+      Note, that we can always perform a reopen in this case,
+      even if we already have metadata locks, since we don't
+      keep tables open between statements and a livelock
+      is not possible.
+  */
+  if (action_arg == OT_BACKOFF_AND_RETRY && m_has_locks)
+  {
+    my_error(ER_LOCK_DEADLOCK, MYF(0));
+    m_thd->mark_transaction_to_rollback(true);
+    return TRUE;
+  }
+  /*
+    If auto-repair or discovery are requested, a pointer to table
+    list element must be provided.
+  */
+  if (table)
+  {
+    DBUG_ASSERT(action_arg == OT_DISCOVER || action_arg == OT_REPAIR);
+    m_failed_table= (TABLE_LIST*) m_thd->alloc(sizeof(TABLE_LIST));
+    if (m_failed_table == NULL)
+      return TRUE;
+    m_failed_table->init_one_table(&table->db, &table->table_name, &table->alias, TL_WRITE);
+    m_failed_table->open_strategy= table->open_strategy;
+    m_failed_table->mdl_request.set_type(MDL_EXCLUSIVE);
+  }
+  m_action= action_arg;
+  return FALSE;
+}
+
+
+/**
+  An error handler to mark transaction to rollback on DEADLOCK error
+  during DISCOVER / REPAIR.
+*/
+class MDL_deadlock_discovery_repair_handler : public Internal_error_handler
+{
+public:
+  virtual bool handle_condition(THD *thd,
+                                  uint sql_errno,
+                                  const char* sqlstate,
+                                  Sql_condition::enum_warning_level *level,
+                                  const char* msg,
+                                  Sql_condition ** cond_hdl)
+  {
+    if (sql_errno == ER_LOCK_DEADLOCK)
+    {
+      thd->mark_transaction_to_rollback(true);
+    }
+    /*
+      We have marked this transaction to rollback. Return false to allow
+      error to be reported or handled by other handlers.
+    */
+    return false;
+  }
+};
+
+/**
+   Recover from failed attempt of open table by performing requested action.
+
+   @pre This function should be called only with "action" != OT_NO_ACTION
+        and after having called @sa close_tables_for_reopen().
+
+   @retval FALSE - Success. One should try to open tables once again.
+   @retval TRUE  - Error
+*/
+
+bool
+Open_table_context::recover_from_failed_open()
+{
+  bool result= FALSE;
+  MDL_deadlock_discovery_repair_handler handler;
+  /*
+    Install error handler to mark transaction to rollback on DEADLOCK error.
+  */
+  m_thd->push_internal_handler(&handler);
+
+  /* Execute the action. */
+  switch (m_action)
+  {
+    case OT_BACKOFF_AND_RETRY:
+    case OT_REOPEN_TABLES:
+      break;
+    case OT_DISCOVER:
+    case OT_REPAIR:
+      if ((result= lock_table_names(m_thd, m_thd->lex->create_info,
+                                    m_failed_table, NULL,
+                                    get_timeout(), 0)))
+        break;
+
+      tdc_remove_table(m_thd, m_failed_table->db.str,
+                       m_failed_table->table_name.str);
+
+      switch (m_action)
+      {
+        case OT_DISCOVER:
+        {
+          m_thd->get_stmt_da()->clear_warning_info(m_thd->query_id);
+          m_thd->clear_error();                 // Clear error message
+
+          No_such_table_error_handler no_such_table_handler;
+          bool open_if_exists= m_failed_table->open_strategy == TABLE_LIST::OPEN_IF_EXISTS;
+
+          if (open_if_exists)
+            m_thd->push_internal_handler(&no_such_table_handler);
+
+          result= !tdc_acquire_share(m_thd, m_failed_table,
+                                 GTS_TABLE | GTS_FORCE_DISCOVERY | GTS_NOLOCK);
+          if (open_if_exists)
+          {
+            m_thd->pop_internal_handler();
+            if (result && no_such_table_handler.safely_trapped_errors())
+              result= FALSE;
+          }
+          break;
+        }
+        case OT_REPAIR:
+          result= auto_repair_table(m_thd, m_failed_table);
+          break;
+        case OT_BACKOFF_AND_RETRY:
+        case OT_REOPEN_TABLES:
+        case OT_NO_ACTION:
+          DBUG_ASSERT(0);
+      }
+      /*
+        Rollback to start of the current statement to release exclusive lock
+        on table which was discovered but preserve locks from previous statements
+        in current transaction.
+      */
+      m_thd->mdl_context.rollback_to_savepoint(start_of_statement_svp());
+      break;
+    case OT_NO_ACTION:
+      DBUG_ASSERT(0);
+  }
+  m_thd->pop_internal_handler();
+  /*
+    Reset the pointers to conflicting MDL request and the
+    TABLE_LIST element, set when we need auto-discovery or repair,
+    for safety.
+  */
+  m_failed_table= NULL;
+  /*
+    Reset flag indicating that we have already acquired protection
+    against GRL. It is no longer valid as the corresponding lock was
+    released by close_tables_for_reopen().
+  */
+  m_has_protection_against_grl= 0;
+  /* Prepare for possible another back-off. */
+  m_action= OT_NO_ACTION;
+  return result;
+}
+
+
+/*
+  Return a appropriate read lock type given a table object.
+
+  @param thd              Thread context
+  @param prelocking_ctx   Prelocking context.
+  @param table_list       Table list element for table to be locked.
+  @param routine_modifies_data
+                          Some routine that is invoked by statement
+                          modifies data.
+
+  @remark Due to a statement-based replication limitation, statements such as
+          INSERT INTO .. SELECT FROM .. and CREATE TABLE .. SELECT FROM need
+          to grab a TL_READ_NO_INSERT lock on the source table in order to
+          prevent the replication of a concurrent statement that modifies the
+          source table. If such a statement gets applied on the slave before
+          the INSERT .. SELECT statement finishes, data on the master could
+          differ from data on the slave and end-up with a discrepancy between
+          the binary log and table state.
+          This also applies to SELECT/SET/DO statements which use stored
+          functions. Calls to such functions are going to be logged as a
+          whole and thus should be serialized against concurrent changes
+          to tables used by those functions. This is avoided when functions
+          do not modify data but only read it, since in this case nothing is
+          written to the binary log. Argument routine_modifies_data
+          denotes the same. So effectively, if the statement is not a
+          update query and routine_modifies_data is false, then
+          prelocking_placeholder does not take importance.
+
+          Furthermore, this does not apply to I_S and log tables as it's
+          always unsafe to replicate such tables under statement-based
+          replication as the table on the slave might contain other data
+          (ie: general_log is enabled on the slave). The statement will
+          be marked as unsafe for SBR in decide_logging_format().
+  @remark Note that even in prelocked mode it is important to correctly
+          determine lock type value. In this mode lock type is passed to
+          handler::start_stmt() method and can be used by storage engine,
+          for example, to determine what kind of row locks it should acquire
+          when reading data from the table.
+*/
+
+thr_lock_type read_lock_type_for_table(THD *thd,
+                                       Query_tables_list *prelocking_ctx,
+                                       TABLE_LIST *table_list,
+                                       bool routine_modifies_data)
+{
+  /*
+    In cases when this function is called for a sub-statement executed in
+    prelocked mode we can't rely on OPTION_BIN_LOG flag in THD::options
+    bitmap to determine that binary logging is turned on as this bit can
+    be cleared before executing sub-statement. So instead we have to look
+    at THD::variables::sql_log_bin member.
+  */
+  bool log_on= mysql_bin_log.is_open() && thd->variables.sql_log_bin;
+  if ((log_on == FALSE) || (thd->wsrep_binlog_format() == BINLOG_FORMAT_ROW) ||
+      (table_list->table->s->table_category == TABLE_CATEGORY_LOG) ||
+      (table_list->table->s->table_category == TABLE_CATEGORY_PERFORMANCE) ||
+      !(is_update_query(prelocking_ctx->sql_command) ||
+        (routine_modifies_data && table_list->prelocking_placeholder) ||
+        (thd->locked_tables_mode > LTM_LOCK_TABLES)))
+    return TL_READ;
+  else
+    return TL_READ_NO_INSERT;
+}
+
+
+/*
+  Extend the prelocking set with tables and routines used by a routine.
+
+  @param[in]  thd                   Thread context.
+  @param[in]  rt                    Element of prelocking set to be processed.
+  @param[in]  ot_ctx                Context of open_table used to recover from
+                                    locking failures.
+  @retval false  Success.
+  @retval true   Failure (Conflicting metadata lock, OOM, other errors).
+*/
+static bool
+sp_acquire_mdl(THD *thd, Sroutine_hash_entry *rt, Open_table_context *ot_ctx)
+{
+  DBUG_ENTER("sp_acquire_mdl");
+  /*
+    Since we acquire only shared lock on routines we don't
+    need to care about global intention exclusive locks.
+  */
+  DBUG_ASSERT(rt->mdl_request.type == MDL_SHARED);
+
+  /*
+    Waiting for a conflicting metadata lock to go away may
+    lead to a deadlock, detected by MDL subsystem.
+    If possible, we try to resolve such deadlocks by releasing all
+    metadata locks and restarting the pre-locking process.
+    To prevent the error from polluting the diagnostics area
+    in case of successful resolution, install a special error
+    handler for ER_LOCK_DEADLOCK error.
+  */
+  MDL_deadlock_handler mdl_deadlock_handler(ot_ctx);
+
+  thd->push_internal_handler(&mdl_deadlock_handler);
+  bool result= thd->mdl_context.acquire_lock(&rt->mdl_request,
+                                             ot_ctx->get_timeout());
+  thd->pop_internal_handler();
+
+  DBUG_RETURN(result);
+}
+
+
+/*
+  Handle element of prelocking set other than table. E.g. cache routine
+  and, if prelocking strategy prescribes so, extend the prelocking set
+  with tables and routines used by it.
+
+  @param[in]  thd                   Thread context.
+  @param[in]  prelocking_ctx        Prelocking context.
+  @param[in]  rt                    Element of prelocking set to be processed.
+  @param[in]  prelocking_strategy   Strategy which specifies how the
+                                    prelocking set should be extended when
+                                    one of its elements is processed.
+  @param[in]  has_prelocking_list   Indicates that prelocking set/list for
+                                    this statement has already been built.
+  @param[in]  ot_ctx                Context of open_table used to recover from
+                                    locking failures.
+  @param[out] need_prelocking       Set to TRUE if it was detected that this
+                                    statement will require prelocked mode for
+                                    its execution, not touched otherwise.
+  @param[out] routine_modifies_data Set to TRUE if it was detected that this
+                                    routine does modify table data.
+
+  @retval FALSE  Success.
+  @retval TRUE   Failure (Conflicting metadata lock, OOM, other errors).
+*/
+
+static bool
+open_and_process_routine(THD *thd, Query_tables_list *prelocking_ctx,
+                         Sroutine_hash_entry *rt,
+                         Prelocking_strategy *prelocking_strategy,
+                         bool has_prelocking_list,
+                         Open_table_context *ot_ctx,
+                         bool *need_prelocking, bool *routine_modifies_data)
+{
+  MDL_key::enum_mdl_namespace mdl_type= rt->mdl_request.key.mdl_namespace();
+  DBUG_ENTER("open_and_process_routine");
+
+  *routine_modifies_data= false;
+
+  switch (mdl_type)
+  {
+  case MDL_key::PACKAGE_BODY:
+    DBUG_ASSERT(rt != (Sroutine_hash_entry*)prelocking_ctx->sroutines_list.first);
+    /*
+      No need to cache the package body itself.
+      It gets cached during open_and_process_routine()
+      for the first used package routine. See the package related code
+      in the "case" below.
+    */
+    if (sp_acquire_mdl(thd, rt, ot_ctx))
+      DBUG_RETURN(TRUE);
+    break;
+  case MDL_key::FUNCTION:
+  case MDL_key::PROCEDURE:
+    {
+      sp_head *sp;
+      /*
+        Try to get MDL lock on the routine.
+        Note that we do not take locks on top-level CALLs as this can
+        lead to a deadlock. Not locking top-level CALLs does not break
+        the binlog as only the statements in the called procedure show
+        up there, not the CALL itself.
+      */
+      if (rt != (Sroutine_hash_entry*)prelocking_ctx->sroutines_list.first ||
+          mdl_type != MDL_key::PROCEDURE)
+      {
+        /*
+          TODO: If this is a package routine, we should not put MDL
+          TODO: on the routine itself. We should put only the package MDL.
+        */
+        if (sp_acquire_mdl(thd, rt, ot_ctx))
+          DBUG_RETURN(TRUE);
+
+        /* Ensures the routine is up-to-date and cached, if exists. */
+        if (rt->sp_cache_routine(thd, has_prelocking_list, &sp))
+          DBUG_RETURN(TRUE);
+
+        /* Remember the version of the routine in the parse tree. */
+        if (check_and_update_routine_version(thd, rt, sp))
+          DBUG_RETURN(TRUE);
+
+        /* 'sp' is NULL when there is no such routine. */
+        if (sp)
+        {
+          *routine_modifies_data= sp->modifies_data();
+
+          if (!has_prelocking_list)
+          {
+            prelocking_strategy->handle_routine(thd, prelocking_ctx, rt, sp,
+                                                need_prelocking);
+            if (sp->m_parent)
+            {
+              /*
+                If it's a package routine, we need also to handle the
+                package body, as its initialization section can use
+                some tables and routine calls.
+                TODO: Only package public routines actually need this.
+                TODO: Skip package body handling for private routines.
+              */
+              *routine_modifies_data|= sp->m_parent->modifies_data();
+              prelocking_strategy->handle_routine(thd, prelocking_ctx, rt,
+                                                  sp->m_parent,
+                                                  need_prelocking);
+            }
+          }
+        }
+      }
+      else
+      {
+        /*
+          If it's a top level call, just make sure we have a recent
+          version of the routine, if it exists.
+          Validating routine version is unnecessary, since CALL
+          does not affect the prepared statement prelocked list.
+        */
+        if (rt->sp_cache_routine(thd, false, &sp))
+          DBUG_RETURN(TRUE);
+      }
+    }
+    break;
+  case MDL_key::TRIGGER:
+    /**
+      We add trigger entries to lex->sroutines_list, but we don't
+      load them here. The trigger entry is only used when building
+      a transitive closure of objects used in a statement, to avoid
+      adding to this closure objects that are used in the trigger more
+      than once.
+      E.g. if a trigger trg refers to table t2, and the trigger table t1
+      is used multiple times in the statement (say, because it's used in
+      function f1() twice), we will only add t2 once to the list of
+      tables to prelock.
+
+      We don't take metadata locks on triggers either: they are protected
+      by a respective lock on the table, on which the trigger is defined.
+
+      The only two cases which give "trouble" are SHOW CREATE TRIGGER
+      and DROP TRIGGER statements. For these, statement syntax doesn't
+      specify the table on which this trigger is defined, so we have
+      to make a "dirty" read in the data dictionary to find out the
+      table name. Once we discover the table name, we take a metadata
+      lock on it, and this protects all trigger operations.
+      Of course the table, in theory, may disappear between the dirty
+      read and metadata lock acquisition, but in that case we just return
+      a run-time error.
+
+      Grammar of other trigger DDL statements (CREATE, DROP) requires
+      the table to be specified explicitly, so we use the table metadata
+      lock to protect trigger metadata in these statements. Similarly, in
+      DML we always use triggers together with their tables, and thus don't
+      need to take separate metadata locks on them.
+    */
+    break;
+  default:
+    /* Impossible type value. */
+    DBUG_ASSERT(0);
+  }
+  DBUG_RETURN(FALSE);
+}
+
+/*
+  If we are not already in prelocked mode and extended table list is not
+  yet built we might have to build the prelocking set for this statement.
+
+  Since currently no prelocking strategy prescribes doing anything for
+  tables which are only read, we do below checks only if table is going
+  to be changed.
+*/
+bool extend_table_list(THD *thd, TABLE_LIST *tables,
+                       Prelocking_strategy *prelocking_strategy,
+                       bool has_prelocking_list)
+{
+  bool error= false;
+  LEX *lex= thd->lex;
+  bool maybe_need_prelocking=
+    (tables->updating && tables->lock_type >= TL_WRITE_ALLOW_WRITE)
+    || thd->lex->default_used;
+
+  if (thd->locked_tables_mode <= LTM_LOCK_TABLES &&
+      ! has_prelocking_list && maybe_need_prelocking)
+  {
+    bool need_prelocking= FALSE;
+    TABLE_LIST **save_query_tables_last= lex->query_tables_last;
+    /*
+      Extend statement's table list and the prelocking set with
+      tables and routines according to the current prelocking
+      strategy.
+
+      For example, for DML statements we need to add tables and routines
+      used by triggers which are going to be invoked for this element of
+      table list and also add tables required for handling of foreign keys.
+    */
+    error= prelocking_strategy->handle_table(thd, lex, tables,
+                                             &need_prelocking);
+
+    if (need_prelocking && ! lex->requires_prelocking())
+      lex->mark_as_requiring_prelocking(save_query_tables_last);
+  }
+  return error;
+}
+
+
+/**
+  Handle table list element by obtaining metadata lock, opening table or view
+  and, if prelocking strategy prescribes so, extending the prelocking set with
+  tables and routines used by it.
+
+  @param[in]     thd                  Thread context.
+  @param[in]     lex                  LEX structure for statement.
+  @param[in]     tables               Table list element to be processed.
+  @param[in,out] counter              Number of tables which are open.
+  @param[in]     flags                Bitmap of flags to modify how the tables
+                                      will be open, see open_table() description
+                                      for details.
+  @param[in]     prelocking_strategy  Strategy which specifies how the
+                                      prelocking set should be extended
+                                      when table or view is processed.
+  @param[in]     has_prelocking_list  Indicates that prelocking set/list for
+                                      this statement has already been built.
+  @param[in]     ot_ctx               Context used to recover from a failed
+                                      open_table() attempt.
+
+  @retval  FALSE  Success.
+  @retval  TRUE   Error, reported unless there is a chance to recover from it.
+*/
+
+static bool
+open_and_process_table(THD *thd, TABLE_LIST *tables, uint *counter, uint flags,
+                       Prelocking_strategy *prelocking_strategy,
+                       bool has_prelocking_list, Open_table_context *ot_ctx)
+{
+  bool error= FALSE;
+  bool safe_to_ignore_table= FALSE;
+  LEX *lex= thd->lex;
+  DBUG_ENTER("open_and_process_table");
+  DEBUG_SYNC(thd, "open_and_process_table");
+
+  /*
+    Ignore placeholders for derived tables. After derived tables
+    processing, link to created temporary table will be put here.
+    If this is derived table for view then we still want to process
+    routines used by this view.
+  */
+  if (tables->derived)
+  {
+    if (!tables->view)
+    {
+      if (!tables->is_derived())
+        tables->set_derived();
+      goto end;
+    }
+    /*
+      We restore view's name and database wiped out by derived tables
+      processing and fall back to standard open process in order to
+      obtain proper metadata locks and do other necessary steps like
+      stored routine processing.
+    */
+    tables->db= tables->view_db;
+    tables->table_name= tables->view_name;
+  }
+
+  if (!tables->derived && is_infoschema_db(&tables->db))
+  {
+    /*
+      Check whether the information schema contains a table
+      whose name is tables->schema_table_name
+    */
+    ST_SCHEMA_TABLE *schema_table= tables->schema_table;
+    if (!schema_table ||
+        (schema_table->hidden &&
+         ((sql_command_flags[lex->sql_command] & CF_STATUS_COMMAND) == 0 ||
+          /*
+            this check is used for show columns|keys from I_S hidden table
+          */
+          lex->sql_command == SQLCOM_SHOW_FIELDS ||
+          lex->sql_command == SQLCOM_SHOW_KEYS)))
+    {
+      my_error(ER_UNKNOWN_TABLE, MYF(0),
+               tables->table_name.str, INFORMATION_SCHEMA_NAME.str);
+      DBUG_RETURN(1);
+    }
+  }
+  /*
+    If this TABLE_LIST object is a placeholder for an information_schema
+    table, create a temporary table to represent the information_schema
+    table in the query. Do not fill it yet - will be filled during
+    execution.
+  */
+  if (tables->schema_table)
+  {
+    /*
+      If this information_schema table is merged into a mergeable
+      view, ignore it for now -- it will be filled when its respective
+      TABLE_LIST is processed. This code works only during re-execution.
+    */
+    if (tables->view)
+    {
+      MDL_ticket *mdl_ticket;
+      /*
+        We still need to take a MDL lock on the merged view to protect
+        it from concurrent changes.
+      */
+      if (!open_table_get_mdl_lock(thd, ot_ctx, &tables->mdl_request,
+                                   flags, &mdl_ticket) &&
+          mdl_ticket != NULL)
+        goto process_view_routines;
+      /* Fall-through to return error. */
+    }
+    else if (!mysql_schema_table(thd, lex, tables) &&
+             !check_and_update_table_version(thd, tables, tables->table->s))
+    {
+      goto end;
+    }
+    error= TRUE;
+    goto end;
+  }
+  DBUG_PRINT("tcache", ("opening table: '%s'.'%s'  item: %p",
+                        tables->db.str, tables->table_name.str, tables));
+  (*counter)++;
+
+  /*
+    Not a placeholder: must be a base/temporary table or a view. Let us open it.
+  */
+  if (tables->table)
+  {
+    /*
+      If this TABLE_LIST object has an associated open TABLE object
+      (TABLE_LIST::table is not NULL), that TABLE object must be a pre-opened
+      temporary table or SEQUENCE (see sequence_insert()).
+    */
+    DBUG_ASSERT(is_temporary_table(tables) || tables->table->s->sequence);
+    if (tables->sequence &&
+        tables->table->s->table_type != TABLE_TYPE_SEQUENCE)
+    {
+      my_error(ER_NOT_SEQUENCE, MYF(0), tables->db.str, tables->alias.str);
+      DBUG_RETURN(true);
+    }
+  }
+  else if (tables->open_type == OT_TEMPORARY_ONLY)
+  {
+    /*
+      OT_TEMPORARY_ONLY means that we are in CREATE TEMPORARY TABLE statement.
+      Also such table list element can't correspond to prelocking placeholder
+      or to underlying table of merge table.
+      So existing temporary table should have been preopened by this moment
+      and we can simply continue without trying to open temporary or base
+      table.
+    */
+    DBUG_ASSERT(tables->open_strategy);
+    DBUG_ASSERT(!tables->prelocking_placeholder);
+    DBUG_ASSERT(!tables->parent_l);
+    DBUG_RETURN(0);
+  }
+
+  /* Not a placeholder: must be a base table or a view. Let us open it. */
+  if (tables->prelocking_placeholder)
+  {
+    /*
+      For the tables added by the pre-locking code, attempt to open
+      the table but fail silently if the table does not exist.
+      The real failure will occur when/if a statement attempts to use
+      that table.
+    */
+    No_such_table_error_handler no_such_table_handler;
+    thd->push_internal_handler(&no_such_table_handler);
+
+    /*
+      We're opening a table from the prelocking list.
+
+      Since this table list element might have been added after pre-opening
+      of temporary tables we have to try to open temporary table for it.
+
+      We can't simply skip this table list element and postpone opening of
+      temporary table till the execution of substatement for several reasons:
+      - Temporary table can be a MERGE table with base underlying tables,
+        so its underlying tables has to be properly open and locked at
+        prelocking stage.
+      - Temporary table can be a MERGE table and we might be in PREPARE
+        phase for a prepared statement. In this case it is important to call
+        HA_ATTACH_CHILDREN for all merge children.
+        This is necessary because merge children remember "TABLE_SHARE ref type"
+        and "TABLE_SHARE def version" in the HA_ATTACH_CHILDREN operation.
+        If HA_ATTACH_CHILDREN is not called, these attributes are not set.
+        Then, during the first EXECUTE, those attributes need to be updated.
+        That would cause statement re-preparing (because changing those
+        attributes during EXECUTE is caught by THD::m_reprepare_observers).
+        The problem is that since those attributes are not set in merge
+        children, another round of PREPARE will not help.
+    */
+    if (!thd->has_temporary_tables() ||
+        (!(error= thd->open_temporary_table(tables)) &&
+         !tables->table))
+      error= open_table(thd, tables, ot_ctx);
+
+    thd->pop_internal_handler();
+    safe_to_ignore_table= no_such_table_handler.safely_trapped_errors();
+  }
+  else if (tables->parent_l && (thd->open_options & HA_OPEN_FOR_REPAIR))
+  {
+    /*
+      Also fail silently for underlying tables of a MERGE table if this
+      table is opened for CHECK/REPAIR TABLE statement. This is needed
+      to provide complete list of problematic underlying tables in
+      CHECK/REPAIR TABLE output.
+    */
+    Repair_mrg_table_error_handler repair_mrg_table_handler;
+    thd->push_internal_handler(&repair_mrg_table_handler);
+
+    if (!thd->has_temporary_tables() ||
+        (!(error= thd->open_temporary_table(tables)) &&
+         !tables->table))
+      error= open_table(thd, tables, ot_ctx);
+
+    thd->pop_internal_handler();
+    safe_to_ignore_table= repair_mrg_table_handler.safely_trapped_errors();
+  }
+  else
+  {
+    if (tables->parent_l)
+    {
+      /*
+        Even if we are opening table not from the prelocking list we
+        still might need to look for a temporary table if this table
+        list element corresponds to underlying table of a merge table.
+      */
+      if (thd->has_temporary_tables())
+        error= thd->open_temporary_table(tables);
+    }
+
+    if (!error && !tables->table)
+      error= open_table(thd, tables, ot_ctx);
+  }
+
+  if (unlikely(error))
+  {
+    if (! ot_ctx->can_recover_from_failed_open() && safe_to_ignore_table)
+    {
+      DBUG_PRINT("info", ("open_table: ignoring table '%s'.'%s'",
+                          tables->db.str, tables->alias.str));
+      error= FALSE;
+    }
+    goto end;
+  }
+
+  /*
+    We can't rely on simple check for TABLE_LIST::view to determine
+    that this is a view since during re-execution we might reopen
+    ordinary table in place of view and thus have TABLE_LIST::view
+    set from repvious execution and TABLE_LIST::table set from
+    current.
+  */
+  if (!tables->table && tables->view)
+  {
+    /* VIEW placeholder */
+    (*counter)--;
+
+    /*
+      tables->next_global list consists of two parts:
+      1) Query tables and underlying tables of views.
+      2) Tables used by all stored routines that this statement invokes on
+         execution.
+      We need to know where the bound between these two parts is. If we've
+      just opened a view, which was the last table in part #1, and it
+      has added its base tables after itself, adjust the boundary pointer
+      accordingly.
+    */
+    if (lex->query_tables_own_last == &(tables->next_global) &&
+        tables->view->query_tables)
+      lex->query_tables_own_last= tables->view->query_tables_last;
+    /*
+      Let us free memory used by 'sroutines' hash here since we never
+      call destructor for this LEX.
+    */
+    my_hash_free(&tables->view->sroutines);
+    goto process_view_routines;
+  }
+
+  /*
+    Special types of open can succeed but still don't set
+    TABLE_LIST::table to anything.
+  */
+  if (tables->open_strategy && !tables->table)
+    goto end;
+
+  error= extend_table_list(thd, tables, prelocking_strategy, has_prelocking_list);
+  if (unlikely(error))
+    goto end;
+
+  /* Copy grant information from TABLE_LIST instance to TABLE one. */
+  tables->table->grant= tables->grant;
+
+  /* Check and update metadata version of a base table. */
+  error= check_and_update_table_version(thd, tables, tables->table->s);
+
+  if (unlikely(error))
+    goto end;
+  /*
+    After opening a MERGE table add the children to the query list of
+    tables, so that they are opened too.
+    Note that placeholders don't have the handler open.
+  */
+  /* MERGE tables need to access parent and child TABLE_LISTs. */
+  DBUG_ASSERT(tables->table->pos_in_table_list == tables);
+  /* Non-MERGE tables ignore this call. */
+  if (tables->table->file->extra(HA_EXTRA_ADD_CHILDREN_LIST))
+  {
+    error= TRUE;
+    goto end;
+  }
+
+process_view_routines:
+  /*
+    Again we may need cache all routines used by this view and add
+    tables used by them to table list.
+  */
+  if (tables->view &&
+      thd->locked_tables_mode <= LTM_LOCK_TABLES &&
+      ! has_prelocking_list)
+  {
+    bool need_prelocking= FALSE;
+    TABLE_LIST **save_query_tables_last= lex->query_tables_last;
+
+    error= prelocking_strategy->handle_view(thd, lex, tables,
+                                            &need_prelocking);
+
+    if (need_prelocking && ! lex->requires_prelocking())
+      lex->mark_as_requiring_prelocking(save_query_tables_last);
+
+    if (unlikely(error))
+      goto end;
+  }
+
+end:
+  DBUG_RETURN(error);
+}
+
+
+static bool upgrade_lock_if_not_exists(THD *thd,
+                                       const DDL_options_st &create_info,
+                                       TABLE_LIST *create_table,
+                                       ulong lock_wait_timeout)
+{
+  DBUG_ENTER("upgrade_lock_if_not_exists");
+
+  if (thd->lex->sql_command == SQLCOM_CREATE_TABLE ||
+      thd->lex->sql_command == SQLCOM_CREATE_SEQUENCE)
+  {
+    DEBUG_SYNC(thd,"create_table_before_check_if_exists");
+    if (!create_info.or_replace() &&
+        ha_table_exists(thd, &create_table->db, &create_table->table_name,
+                        &create_table->db_type))
+    {
+      if (create_info.if_not_exists())
+      {
+        push_warning_printf(thd, Sql_condition::WARN_LEVEL_NOTE,
+                            ER_TABLE_EXISTS_ERROR,
+                            ER_THD(thd, ER_TABLE_EXISTS_ERROR),
+                            create_table->table_name.str);
+      }
+      else
+        my_error(ER_TABLE_EXISTS_ERROR, MYF(0), create_table->table_name.str);
+      DBUG_RETURN(true);
+    }
+    DBUG_RETURN(thd->mdl_context.upgrade_shared_lock(
+                                   create_table->mdl_request.ticket,
+                                   MDL_EXCLUSIVE,
+                                   lock_wait_timeout));
+  }
+  DBUG_RETURN(false);
+}
+
+
+/**
+  Acquire upgradable (SNW, SNRW) metadata locks on tables used by
+  LOCK TABLES or by a DDL statement. Under LOCK TABLES, we can't take
+  new locks, so use open_tables_check_upgradable_mdl() instead.
+
+  @param thd               Thread context.
+  @param options           DDL options.
+  @param tables_start      Start of list of tables on which upgradable locks
+                           should be acquired.
+  @param tables_end        End of list of tables.
+  @param lock_wait_timeout Seconds to wait before timeout.
+  @param flags             Bitmap of flags to modify how the tables will be
+                           open, see open_table() description for details.
+
+  @retval FALSE  Success.
+  @retval TRUE   Failure (e.g. connection was killed) or table existed
+	         for a CREATE TABLE.
+
+  @notes
+  In case of CREATE TABLE we avoid a wait for tables that are in use
+  by first trying to do a meta data lock with timeout == 0.  If we get a
+  timeout we will check if table exists (it should) and retry with
+  normal timeout if it didn't exists.
+  Note that for CREATE TABLE IF EXISTS we only generate a warning
+  but still return TRUE (to abort the calling open_table() function).
+  On must check THD->is_error() if one wants to distinguish between warning
+  and error.  If table existed, tables_start->db_type is set to the handlerton
+  for the found table.
+*/
+
+bool
+lock_table_names(THD *thd, const DDL_options_st &options,
+                 TABLE_LIST *tables_start, TABLE_LIST *tables_end,
+                 ulong lock_wait_timeout, uint flags)
+{
+  MDL_request_list mdl_requests;
+  TABLE_LIST *table;
+  MDL_request global_request;
+  MDL_savepoint mdl_savepoint;
+  DBUG_ENTER("lock_table_names");
+
+  DBUG_ASSERT(!thd->locked_tables_mode);
+
+  for (table= tables_start; table && table != tables_end;
+       table= table->next_global)
+  {
+    DBUG_PRINT("info", ("mdl_request.type: %d  open_type: %d",
+                        table->mdl_request.type, table->open_type));
+    if (table->mdl_request.type < MDL_SHARED_UPGRADABLE ||
+        table->mdl_request.type == MDL_SHARED_READ_ONLY ||
+        table->open_type == OT_TEMPORARY_ONLY ||
+        (table->open_type == OT_TEMPORARY_OR_BASE && is_temporary_table(table)))
+    {
+      continue;
+    }
+
+    /* Write lock on normal tables is not allowed in a read only transaction. */
+    if (thd->tx_read_only)
+    {
+      my_error(ER_CANT_EXECUTE_IN_READ_ONLY_TRANSACTION, MYF(0));
+      DBUG_RETURN(true);
+    }
+
+    /* Scoped locks: Take intention exclusive locks on all involved schemas. */
+    if (!(flags & MYSQL_OPEN_SKIP_SCOPED_MDL_LOCK))
+    {
+      MDL_request *schema_request= new (thd->mem_root) MDL_request;
+      if (schema_request == NULL)
+        DBUG_RETURN(TRUE);
+      MDL_REQUEST_INIT(schema_request, MDL_key::SCHEMA, table->db.str, "",
+                       MDL_INTENTION_EXCLUSIVE, MDL_TRANSACTION);
+      mdl_requests.push_front(schema_request);
+    }
+
+    mdl_requests.push_front(&table->mdl_request);
+  }
+
+  if (mdl_requests.is_empty())
+    DBUG_RETURN(FALSE);
+
+  if (flags & MYSQL_OPEN_SKIP_SCOPED_MDL_LOCK)
+  {
+    DBUG_RETURN(thd->mdl_context.acquire_locks(&mdl_requests,
+                                               lock_wait_timeout) ||
+                upgrade_lock_if_not_exists(thd, options, tables_start,
+                                           lock_wait_timeout));
+  }
+
+  /* Protect this statement against concurrent BACKUP STAGE or FTWRL. */
+  if (thd->has_read_only_protection())
+    DBUG_RETURN(true);
+
+  MDL_REQUEST_INIT(&global_request, MDL_key::BACKUP, "", "", MDL_BACKUP_DDL,
+                   MDL_STATEMENT);
+  mdl_savepoint= thd->mdl_context.mdl_savepoint();
+
+  while (!thd->mdl_context.acquire_locks(&mdl_requests, lock_wait_timeout) &&
+         !upgrade_lock_if_not_exists(thd, options, tables_start,
+                                     lock_wait_timeout) &&
+         !thd->mdl_context.try_acquire_lock(&global_request))
+  {
+    if (global_request.ticket)
+    {
+      thd->mdl_backup_ticket= global_request.ticket;
+      DBUG_RETURN(false);
+    }
+
+    /*
+      There is ongoing or pending BACKUP STAGE or FTWRL.
+      Wait until it finishes and re-try.
+    */
+    thd->mdl_context.rollback_to_savepoint(mdl_savepoint);
+    if (thd->mdl_context.acquire_lock(&global_request, lock_wait_timeout))
+      break;
+    thd->mdl_context.rollback_to_savepoint(mdl_savepoint);
+
+    /* Reset tickets for all acquired locks */
+    global_request.ticket= 0;
+    MDL_request_list::Iterator it(mdl_requests);
+    while (auto mdl_request= it++)
+      mdl_request->ticket= 0;
+  }
+  DBUG_RETURN(true);
+}
+
+
+/**
+  Check for upgradable (SNW, SNRW) metadata locks on tables to be opened
+  for a DDL statement. Under LOCK TABLES, we can't take new locks, so we
+  must check if appropriate locks were pre-acquired.
+
+  @param thd           Thread context.
+  @param tables_start  Start of list of tables on which upgradable locks
+                       should be searched for.
+  @param tables_end    End of list of tables.
+  @param flags         Bitmap of flags to modify how the tables will be
+                       open, see open_table() description for details.
+
+  @retval FALSE  Success.
+  @retval TRUE   Failure (e.g. connection was killed)
+*/
+
+static bool
+open_tables_check_upgradable_mdl(THD *thd, TABLE_LIST *tables_start,
+                                 TABLE_LIST *tables_end, uint flags)
+{
+  TABLE_LIST *table;
+
+  DBUG_ASSERT(thd->locked_tables_mode);
+
+  for (table= tables_start; table && table != tables_end;
+       table= table->next_global)
+  {
+    /*
+      Check below needs to be updated if this function starts
+      called for SRO locks.
+    */
+    DBUG_ASSERT(table->mdl_request.type != MDL_SHARED_READ_ONLY);
+    if (table->mdl_request.type < MDL_SHARED_UPGRADABLE ||
+        table->open_type == OT_TEMPORARY_ONLY ||
+        (table->open_type == OT_TEMPORARY_OR_BASE && is_temporary_table(table)))
+    {
+      continue;
+    }
+
+    /*
+      We don't need to do anything about the found TABLE instance as it
+      will be handled later in open_tables(), we only need to check that
+      an upgradable lock is already acquired. When we enter LOCK TABLES
+      mode, SNRW locks are acquired before all other locks. So if under
+      LOCK TABLES we find that there is TABLE instance with upgradeable
+      lock, all other instances of TABLE for the same table will have the
+      same ticket.
+
+      Note that this works OK even for CREATE TABLE statements which
+      request X type of metadata lock. This is because under LOCK TABLES
+      such statements don't create the table but only check if it exists
+      or, in most complex case, only insert into it.
+      Thus SNRW lock should be enough.
+
+      Note that find_table_for_mdl_upgrade() will report an error if
+      no suitable ticket is found.
+    */
+    if (!find_table_for_mdl_upgrade(thd, table->db.str, table->table_name.str,
+                                    NULL))
+      return TRUE;
+  }
+
+  return FALSE;
+}
+
+
+/**
+  Open all tables in list
+
+  @param[in]     thd      Thread context.
+  @param[in]     options  DDL options.
+  @param[in,out] start    List of tables to be open (it can be adjusted for
+                          statement that uses tables only implicitly, e.g.
+                          for "SELECT f1()").
+  @param[out]    counter  Number of tables which were open.
+  @param[in]     flags    Bitmap of flags to modify how the tables will be
+                          open, see open_table() description for details.
+  @param[in]     prelocking_strategy  Strategy which specifies how prelocking
+                                      algorithm should work for this statement.
+
+  @note
+    Unless we are already in prelocked mode and prelocking strategy prescribes
+    so this function will also precache all SP/SFs explicitly or implicitly
+    (via views and triggers) used by the query and add tables needed for their
+    execution to table list. Statement that uses SFs, invokes triggers or
+    requires foreign key checks will be marked as requiring prelocking.
+    Prelocked mode will be enabled for such query during lock_tables() call.
+
+    If query for which we are opening tables is already marked as requiring
+    prelocking it won't do such precaching and will simply reuse table list
+    which is already built.
+
+  @retval  FALSE  Success.
+  @retval  TRUE   Error, reported.
+*/
+
+bool open_tables(THD *thd, const DDL_options_st &options,
+                 TABLE_LIST **start, uint *counter, uint flags,
+                 Prelocking_strategy *prelocking_strategy)
+{
+  /*
+    We use pointers to "next_global" member in the last processed
+    TABLE_LIST element and to the "next" member in the last processed
+    Sroutine_hash_entry element as iterators over, correspondingly,
+    the table list and stored routines list which stay valid and allow
+    to continue iteration when new elements are added to the tail of
+    the lists.
+  */
+  TABLE_LIST **table_to_open;
+  Sroutine_hash_entry **sroutine_to_open;
+  TABLE_LIST *tables;
+  Open_table_context ot_ctx(thd, flags);
+  bool error= FALSE;
+  bool some_routine_modifies_data= FALSE;
+  bool has_prelocking_list;
+  DBUG_ENTER("open_tables");
+
+  /* Data access in XA transaction is only allowed when it is active. */
+  for (TABLE_LIST *table= *start; table; table= table->next_global)
+    if (!table->schema_table)
+    {
+      if (thd->transaction->xid_state.check_has_uncommitted_xa())
+      {
+	thd->transaction->xid_state.er_xaer_rmfail();
+        DBUG_RETURN(true);
+      }
+      else
+        break;
+    }
+
+  thd->current_tablenr= 0;
+restart:
+  /*
+    Close HANDLER tables which are marked for flush or against which there
+    are pending exclusive metadata locks. This is needed both in order to
+    avoid deadlocks and to have a point during statement execution at
+    which such HANDLERs are closed even if they don't create problems for
+    the current session (i.e. to avoid having a DDL blocked by HANDLERs
+    opened for a long time).
+  */
+  if (thd->handler_tables_hash.records)
+    mysql_ha_flush(thd);
+
+  has_prelocking_list= thd->lex->requires_prelocking();
+  table_to_open= start;
+  sroutine_to_open= &thd->lex->sroutines_list.first;
+  *counter= 0;
+  THD_STAGE_INFO(thd, stage_opening_tables);
+  prelocking_strategy->reset(thd);
+
+  /*
+    If we are executing LOCK TABLES statement or a DDL statement
+    (in non-LOCK TABLES mode) we might have to acquire upgradable
+    semi-exclusive metadata locks (SNW or SNRW) on some of the
+    tables to be opened.
+    When executing CREATE TABLE .. If NOT EXISTS .. SELECT, the
+    table may not yet exist, in which case we acquire an exclusive
+    lock.
+    We acquire all such locks at once here as doing this in one
+    by one fashion may lead to deadlocks or starvation. Later when
+    we will be opening corresponding table pre-acquired metadata
+    lock will be reused (thanks to the fact that in recursive case
+    metadata locks are acquired without waiting).
+  */
+  if (! (flags & (MYSQL_OPEN_HAS_MDL_LOCK |
+                  MYSQL_OPEN_FORCE_SHARED_MDL |
+                  MYSQL_OPEN_FORCE_SHARED_HIGH_PRIO_MDL)))
+  {
+    if (thd->locked_tables_mode)
+    {
+      /*
+        Under LOCK TABLES, we can't acquire new locks, so we instead
+        need to check if appropriate locks were pre-acquired.
+      */
+      if (open_tables_check_upgradable_mdl(thd, *start,
+                                           thd->lex->first_not_own_table(),
+                                           flags))
+      {
+        error= TRUE;
+        goto error;
+      }
+    }
+    else
+    {
+      TABLE_LIST *table;
+      if (lock_table_names(thd, options, *start,
+                           thd->lex->first_not_own_table(),
+                           ot_ctx.get_timeout(), flags))
+      {
+        error= TRUE;
+        goto error;
+      }
+      for (table= *start; table && table != thd->lex->first_not_own_table();
+           table= table->next_global)
+      {
+        if (table->mdl_request.type >= MDL_SHARED_UPGRADABLE)
+          table->mdl_request.ticket= NULL;
+      }
+    }
+  }
+
+  /*
+    Perform steps of prelocking algorithm until there are unprocessed
+    elements in prelocking list/set.
+  */
+  while (*table_to_open  ||
+         (thd->locked_tables_mode <= LTM_LOCK_TABLES && *sroutine_to_open))
+  {
+    /*
+      For every table in the list of tables to open, try to find or open
+      a table.
+    */
+    for (tables= *table_to_open; tables;
+         table_to_open= &tables->next_global, tables= tables->next_global)
+    {
+      error= open_and_process_table(thd, tables, counter, flags,
+                                    prelocking_strategy, has_prelocking_list,
+                                    &ot_ctx);
+
+      if (unlikely(error))
+      {
+        if (ot_ctx.can_recover_from_failed_open())
+        {
+          /*
+            We have met exclusive metadata lock or old version of table.
+            Now we have to close all tables and release metadata locks.
+            We also have to throw away set of prelocked tables (and thus
+            close tables from this set that were open by now) since it
+            is possible that one of tables which determined its content
+            was changed.
+
+            Instead of implementing complex/non-robust logic mentioned
+            above we simply close and then reopen all tables.
+
+            We have to save pointer to table list element for table which we
+            have failed to open since closing tables can trigger removal of
+            elements from the table list (if MERGE tables are involved),
+          */
+          close_tables_for_reopen(thd, start, ot_ctx.start_of_statement_svp());
+
+          /*
+            Here we rely on the fact that 'tables' still points to the valid
+            TABLE_LIST element. Altough currently this assumption is valid
+            it may change in future.
+          */
+          if (ot_ctx.recover_from_failed_open())
+            goto error;
+
+          /* Re-open temporary tables after close_tables_for_reopen(). */
+          if (thd->open_temporary_tables(*start))
+            goto error;
+
+          error= FALSE;
+          goto restart;
+        }
+        goto error;
+      }
+
+      DEBUG_SYNC(thd, "open_tables_after_open_and_process_table");
+    }
+
+    /*
+      If we are not already in prelocked mode and extended table list is
+      not yet built for our statement we need to cache routines it uses
+      and build the prelocking list for it.
+      If we are not in prelocked mode but have built the extended table
+      list, we still need to call open_and_process_routine() to take
+      MDL locks on the routines.
+    */
+    if (thd->locked_tables_mode <= LTM_LOCK_TABLES && *sroutine_to_open)
+    {
+      /*
+        Process elements of the prelocking set which are present there
+        since parsing stage or were added to it by invocations of
+        Prelocking_strategy methods in the above loop over tables.
+
+        For example, if element is a routine, cache it and then,
+        if prelocking strategy prescribes so, add tables it uses to the
+        table list and routines it might invoke to the prelocking set.
+      */
+      for (Sroutine_hash_entry *rt= *sroutine_to_open; rt;
+           sroutine_to_open= &rt->next, rt= rt->next)
+      {
+        bool need_prelocking= false;
+        bool routine_modifies_data;
+        TABLE_LIST **save_query_tables_last= thd->lex->query_tables_last;
+
+        error= open_and_process_routine(thd, thd->lex, rt, prelocking_strategy,
+                                        has_prelocking_list, &ot_ctx,
+                                        &need_prelocking,
+                                        &routine_modifies_data);
+
+        // Remember if any of SF modifies data.
+        some_routine_modifies_data|= routine_modifies_data;
+
+        if (need_prelocking && ! thd->lex->requires_prelocking())
+          thd->lex->mark_as_requiring_prelocking(save_query_tables_last);
+
+        if (need_prelocking && ! *start)
+          *start= thd->lex->query_tables;
+
+        if (unlikely(error))
+        {
+          if (ot_ctx.can_recover_from_failed_open())
+          {
+            close_tables_for_reopen(thd, start,
+                                    ot_ctx.start_of_statement_svp());
+            if (ot_ctx.recover_from_failed_open())
+              goto error;
+
+            /* Re-open temporary tables after close_tables_for_reopen(). */
+            if (thd->open_temporary_tables(*start))
+              goto error;
+
+            error= FALSE;
+            goto restart;
+          }
+          /*
+            Serious error during reading stored routines from mysql.proc table.
+            Something is wrong with the table or its contents, and an error has
+            been emitted; we must abort.
+          */
+          goto error;
+        }
+      }
+    }
+    if ((error= prelocking_strategy->handle_end(thd)))
+      goto error;
+  }
+
+  /*
+    After successful open of all tables, including MERGE parents and
+    children, attach the children to their parents. At end of statement,
+    the children are detached. Attaching and detaching are always done,
+    even under LOCK TABLES.
+
+    We also convert all TL_WRITE_DEFAULT and TL_READ_DEFAULT locks to
+    appropriate "real" lock types to be used for locking and to be passed
+    to storage engine.
+
+    And start wsrep TOI if needed.
+  */
+  for (tables= *start; tables; tables= tables->next_global)
+  {
+    TABLE *tbl= tables->table;
+
+    if (!tbl)
+      continue;
+
+    /* Schema tables may not have a TABLE object here. */
+    if (tbl->file->ha_table_flags() & HA_CAN_MULTISTEP_MERGE)
+    {
+      /* MERGE tables need to access parent and child TABLE_LISTs. */
+      DBUG_ASSERT(tbl->pos_in_table_list == tables);
+      if (tbl->file->extra(HA_EXTRA_ATTACH_CHILDREN))
+      {
+        error= TRUE;
+        goto error;
+      }
+    }
+
+    /* Set appropriate TABLE::lock_type. */
+    if (tbl && tables->lock_type != TL_UNLOCK && !thd->locked_tables_mode)
+    {
+      if (tables->lock_type == TL_WRITE_DEFAULT)
+        tbl->reginfo.lock_type= thd->update_lock_default;
+      else if (tables->lock_type == TL_READ_DEFAULT)
+          tbl->reginfo.lock_type=
+            read_lock_type_for_table(thd, thd->lex, tables,
+                                     some_routine_modifies_data);
+      else
+        tbl->reginfo.lock_type= tables->lock_type;
+    }
+  }
+
+#ifdef WITH_WSREP
+  if (WSREP(thd)                                       &&
+      wsrep_replicate_myisam                           &&
+      (*start)                                         &&
+      (*start)->table                                  &&
+      (*start)->table->file->ht == myisam_hton         &&
+      wsrep_thd_is_local(thd)                          &&
+      !is_stat_table(&(*start)->db, &(*start)->alias)  &&
+      thd->get_command() != COM_STMT_PREPARE           &&
+      ((thd->lex->sql_command == SQLCOM_INSERT         ||
+        thd->lex->sql_command == SQLCOM_INSERT_SELECT  ||
+        thd->lex->sql_command == SQLCOM_REPLACE        ||
+        thd->lex->sql_command == SQLCOM_REPLACE_SELECT ||
+        thd->lex->sql_command == SQLCOM_UPDATE         ||
+        thd->lex->sql_command == SQLCOM_UPDATE_MULTI   ||
+        thd->lex->sql_command == SQLCOM_LOAD           ||
+        thd->lex->sql_command == SQLCOM_DELETE)))
+  {
+      wsrep_before_rollback(thd, true);
+      wsrep_after_rollback(thd, true);
+      wsrep_after_statement(thd);
+      WSREP_TO_ISOLATION_BEGIN(NULL, NULL, (*start));
+  }
+#endif /* WITH_WSREP */
+
+error:
+#ifdef WITH_WSREP
+wsrep_error_label:
+#endif
+  THD_STAGE_INFO(thd, stage_after_opening_tables);
+  thd_proc_info(thd, 0);
+
+  if (unlikely(error) && *table_to_open)
+  {
+    (*table_to_open)->table= NULL;
+  }
+  DBUG_PRINT("open_tables", ("returning: %d", (int) error));
+  DBUG_RETURN(error);
+}
+
+
+/**
+  Defines how prelocking algorithm for DML statements should handle routines:
+  - For CALL statements we do unrolling (i.e. open and lock tables for each
+    sub-statement individually). So for such statements prelocking is enabled
+    only if stored functions are used in parameter list and only for period
+    during which we calculate values of parameters. Thus in this strategy we
+    ignore procedure which is directly called by such statement and extend
+    the prelocking set only with tables/functions used by SF called from the
+    parameter list.
+  - For any other statement any routine which is directly or indirectly called
+    by statement is going to be executed in prelocked mode. So in this case we
+    simply add all tables and routines used by it to the prelocking set.
+
+  @param[in]  thd              Thread context.
+  @param[in]  prelocking_ctx   Prelocking context of the statement.
+  @param[in]  rt               Prelocking set element describing routine.
+  @param[in]  sp               Routine body.
+  @param[out] need_prelocking  Set to TRUE if method detects that prelocking
+                               required, not changed otherwise.
+
+  @retval FALSE  Success.
+  @retval TRUE   Failure (OOM).
+*/
+
+bool DML_prelocking_strategy::
+handle_routine(THD *thd, Query_tables_list *prelocking_ctx,
+               Sroutine_hash_entry *rt, sp_head *sp, bool *need_prelocking)
+{
+  /*
+    We assume that for any "CALL proc(...)" statement sroutines_list will
+    have 'proc' as first element (it may have several, consider e.g.
+    "proc(sp_func(...)))". This property is currently guaranted by the
+    parser.
+  */
+
+  if (rt != (Sroutine_hash_entry*)prelocking_ctx->sroutines_list.first ||
+      rt->mdl_request.key.mdl_namespace() != MDL_key::PROCEDURE)
+  {
+    *need_prelocking= TRUE;
+    sp_update_stmt_used_routines(thd, prelocking_ctx, &sp->m_sroutines,
+                                 rt->belong_to_view);
+    (void)sp->add_used_tables_to_table_list(thd,
+                                            &prelocking_ctx->query_tables_last,
+                                            rt->belong_to_view);
+  }
+  sp->propagate_attributes(prelocking_ctx);
+  return FALSE;
+}
+
+
+/*
+  @note this can be changed to use a hash, instead of scanning the linked
+  list, if the performance of this function will ever become an issue
+*/
+bool table_already_fk_prelocked(TABLE_LIST *tl, LEX_CSTRING *db,
+                                LEX_CSTRING *table, thr_lock_type lock_type)
+{
+  for (; tl; tl= tl->next_global )
+  {
+    if (tl->lock_type >= lock_type &&
+        tl->prelocking_placeholder == TABLE_LIST::PRELOCK_FK &&
+        strcmp(tl->db.str, db->str) == 0 &&
+        strcmp(tl->table_name.str, table->str) == 0)
+      return true;
+  }
+  return false;
+}
+
+
+static bool internal_table_exists(TABLE_LIST *global_list,
+                                  const char *table_name)
+{
+  do
+  {
+    if (global_list->table_name.str == table_name)
+      return 1;
+  } while ((global_list= global_list->next_global));
+  return 0;
+}
+
+
+static bool
+add_internal_tables(THD *thd, Query_tables_list *prelocking_ctx,
+                    TABLE_LIST *tables)
+{
+  TABLE_LIST *global_table_list= prelocking_ctx->query_tables;
+  DBUG_ENTER("add_internal_tables");
+
+  do
+  {
+    DBUG_PRINT("info", ("table name: %s", tables->table_name.str));
+    /*
+      Skip table if already in the list. Can happen with prepared statements
+    */
+    if (tables->next_local &&
+        internal_table_exists(global_table_list, tables->table_name.str))
+      continue;
+
+    TABLE_LIST *tl= (TABLE_LIST *) thd->alloc(sizeof(TABLE_LIST));
+    if (!tl)
+      DBUG_RETURN(TRUE);
+    tl->init_one_table_for_prelocking(&tables->db,
+                                      &tables->table_name,
+                                      NULL, tables->lock_type,
+                                      TABLE_LIST::PRELOCK_NONE,
+                                      0, 0,
+                                      &prelocking_ctx->query_tables_last,
+                                      tables->for_insert_data);
+    /*
+      Store link to the new table_list that will be used by open so that
+      Item_func_nextval() can find it
+    */
+    tables->next_local= tl;
+    DBUG_PRINT("info", ("table name: %s added", tables->table_name.str));
+  } while ((tables= tables->next_global));
+  DBUG_RETURN(FALSE);
+}
+
+/**
+  Extend the table_list to include foreign tables for prelocking.
+
+  @param[in]  thd              Thread context.
+  @param[in]  prelocking_ctx   Prelocking context of the statement.
+  @param[in]  table_list       Table list element for table.
+  @param[in]  sp               Routine body.
+  @param[out] need_prelocking  Set to TRUE if method detects that prelocking
+                               required, not changed otherwise.
+
+  @retval FALSE  Success.
+  @retval TRUE   Failure (OOM).
+*/
+inline bool
+prepare_fk_prelocking_list(THD *thd, Query_tables_list *prelocking_ctx,
+                           TABLE_LIST *table_list, bool *need_prelocking,
+                           uint8 op)
+{
+  DBUG_ENTER("prepare_fk_prelocking_list");
+  List <FOREIGN_KEY_INFO> fk_list;
+  List_iterator<FOREIGN_KEY_INFO> fk_list_it(fk_list);
+  FOREIGN_KEY_INFO *fk;
+  Query_arena *arena, backup;
+  TABLE *table= table_list->table;
+
+  arena= thd->activate_stmt_arena_if_needed(&backup);
+
+  table->file->get_parent_foreign_key_list(thd, &fk_list);
+  if (unlikely(thd->is_error()))
+  {
+    if (arena)
+      thd->restore_active_arena(arena, &backup);
+    return TRUE;
+  }
+
+  *need_prelocking= TRUE;
+
+  while ((fk= fk_list_it++))
+  {
+    // FK_OPTION_RESTRICT and FK_OPTION_NO_ACTION only need read access
+    thr_lock_type lock_type;
+
+    if ((op & (1 << TRG_EVENT_DELETE) && fk_modifies_child(fk->delete_method))
+        || (op & (1 << TRG_EVENT_UPDATE) && fk_modifies_child(fk->update_method)))
+      lock_type= TL_WRITE_ALLOW_WRITE;
+    else
+      lock_type= TL_READ;
+
+    if (table_already_fk_prelocked(prelocking_ctx->query_tables,
+          fk->foreign_db, fk->foreign_table,
+          lock_type))
+      continue;
+
+    TABLE_LIST *tl= (TABLE_LIST *) thd->alloc(sizeof(TABLE_LIST));
+    tl->init_one_table_for_prelocking(fk->foreign_db,
+        fk->foreign_table,
+        NULL, lock_type,
+        TABLE_LIST::PRELOCK_FK,
+        table_list->belong_to_view, op,
+        &prelocking_ctx->query_tables_last,
+        table_list->for_insert_data);
+  }
+  if (arena)
+    thd->restore_active_arena(arena, &backup);
+  DBUG_RETURN(FALSE);
+}
+
+/**
+  Defines how prelocking algorithm for DML statements should handle table list
+  elements:
+  - If table has triggers we should add all tables and routines
+    used by them to the prelocking set.
+
+  We do not need to acquire metadata locks on trigger names
+  in DML statements, since all DDL statements
+  that change trigger metadata always lock their
+  subject tables.
+
+  @param[in]  thd              Thread context.
+  @param[in]  prelocking_ctx   Prelocking context of the statement.
+  @param[in]  table_list       Table list element for table.
+  @param[in]  sp               Routine body.
+  @param[out] need_prelocking  Set to TRUE if method detects that prelocking
+                               required, not changed otherwise.
+
+  @retval FALSE  Success.
+  @retval TRUE   Failure (OOM).
+*/
+
+bool DML_prelocking_strategy::
+handle_table(THD *thd, Query_tables_list *prelocking_ctx,
+             TABLE_LIST *table_list, bool *need_prelocking)
+{
+  DBUG_ENTER("handle_table");
+  TABLE *table= table_list->table;
+  /* We rely on a caller to check that table is going to be changed. */
+  DBUG_ASSERT(table_list->lock_type >= TL_WRITE_ALLOW_WRITE ||
+              thd->lex->default_used);
+
+  if (table_list->trg_event_map)
+  {
+    if (table->triggers)
+    {
+      *need_prelocking= TRUE;
+
+      if (table->triggers->
+          add_tables_and_routines_for_triggers(thd, prelocking_ctx, table_list))
+        return TRUE;
+    }
+
+    if (table->file->referenced_by_foreign_key())
+    {
+      if (prepare_fk_prelocking_list(thd, prelocking_ctx, table_list,
+                                     need_prelocking,
+                                     table_list->trg_event_map))
+        return TRUE;
+    }
+  }
+  else if (table_list->slave_fk_event_map &&
+           table->file->referenced_by_foreign_key())
+  {
+    if (prepare_fk_prelocking_list(thd, prelocking_ctx, table_list,
+                                   need_prelocking,
+                                   table_list->slave_fk_event_map))
+      return TRUE;
+  }
+
+  /* Open any tables used by DEFAULT (like sequence tables) */
+  DBUG_PRINT("info", ("table: %p  name: %s  db: %s  flags: %u",
+                      table_list, table_list->table_name.str,
+                      table_list->db.str, table_list->for_insert_data));
+  if (table->internal_tables &&
+      (table_list->for_insert_data ||
+       thd->lex->default_used))
+  {
+    Query_arena *arena, backup;
+    bool error;
+    arena= thd->activate_stmt_arena_if_needed(&backup);
+    error= add_internal_tables(thd, prelocking_ctx,
+                               table->internal_tables);
+    if (arena)
+      thd->restore_active_arena(arena, &backup);
+    if (unlikely(error))
+    {
+      *need_prelocking= TRUE;
+      DBUG_RETURN(TRUE);
+    }
+  }
+  DBUG_RETURN(FALSE);
+}
+
+
+/**
+  Open all tables used by DEFAULT functions.
+
+  This is different from normal open_and_lock_tables() as we may
+  already have other tables opened and locked and we have to merge the
+  new table with the old ones.
+*/
+
+bool open_and_lock_internal_tables(TABLE *table, bool lock_table)
+{
+  THD *thd= table->in_use;
+  TABLE_LIST *tl;
+  MYSQL_LOCK *save_lock,*new_lock;
+  DBUG_ENTER("open_and_lock_internal_tables");
+
+  /* remove pointer to old select_lex which is already destroyed */
+  for (tl= table->internal_tables ; tl ; tl= tl->next_global)
+    tl->select_lex= 0;
+
+  uint counter;
+  MDL_savepoint mdl_savepoint= thd->mdl_context.mdl_savepoint();
+  TABLE_LIST *tmp= table->internal_tables;
+  DML_prelocking_strategy prelocking_strategy;
+
+  if (open_tables(thd, thd->lex->create_info, &tmp, &counter, 0,
+                  &prelocking_strategy))
+    goto err;
+
+  if (lock_table)
+  {
+    save_lock= thd->lock;
+    thd->lock= 0;
+    if (lock_tables(thd, table->internal_tables, counter,
+                    MYSQL_LOCK_USE_MALLOC))
+      goto err;
+
+    if (!(new_lock= mysql_lock_merge(save_lock, thd->lock)))
+    {
+      thd->lock= save_lock;
+      mysql_unlock_tables(thd, save_lock, 1);
+      /* We don't have to close tables as caller will do that */
+      goto err;
+    }
+    thd->lock= new_lock;
+  }
+  DBUG_RETURN(0);
+
+err:
+  thd->mdl_context.rollback_to_savepoint(mdl_savepoint);
+  DBUG_RETURN(1);
+}
+
+
+/**
+  Defines how prelocking algorithm for DML statements should handle view -
+  all view routines should be added to the prelocking set.
+
+  @param[in]  thd              Thread context.
+  @param[in]  prelocking_ctx   Prelocking context of the statement.
+  @param[in]  table_list       Table list element for view.
+  @param[in]  sp               Routine body.
+  @param[out] need_prelocking  Set to TRUE if method detects that prelocking
+                               required, not changed otherwise.
+
+  @retval FALSE  Success.
+  @retval TRUE   Failure (OOM).
+*/
+
+bool DML_prelocking_strategy::
+handle_view(THD *thd, Query_tables_list *prelocking_ctx,
+            TABLE_LIST *table_list, bool *need_prelocking)
+{
+  if (table_list->view->uses_stored_routines())
+  {
+    *need_prelocking= TRUE;
+
+    sp_update_stmt_used_routines(thd, prelocking_ctx,
+                                 &table_list->view->sroutines_list,
+                                 table_list->top_table());
+  }
+
+  /*
+    If a trigger was defined on one of the associated tables then assign the
+    'trg_event_map' value of the view to the next table in table_list. When a
+    Stored function is invoked, all the associated tables including the tables
+    associated with the trigger are prelocked.
+  */
+  if (table_list->trg_event_map && table_list->next_global)
+    table_list->next_global->trg_event_map= table_list->trg_event_map;
+  return FALSE;
+}
+
+
+/**
+  Defines how prelocking algorithm for LOCK TABLES statement should handle
+  table list elements.
+
+  @param[in]  thd              Thread context.
+  @param[in]  prelocking_ctx   Prelocking context of the statement.
+  @param[in]  table_list       Table list element for table.
+  @param[in]  sp               Routine body.
+  @param[out] need_prelocking  Set to TRUE if method detects that prelocking
+                               required, not changed otherwise.
+
+  @retval FALSE  Success.
+  @retval TRUE   Failure (OOM).
+*/
+
+bool Lock_tables_prelocking_strategy::
+handle_table(THD *thd, Query_tables_list *prelocking_ctx,
+             TABLE_LIST *table_list, bool *need_prelocking)
+{
+  TABLE_LIST **last= prelocking_ctx->query_tables_last;
+
+  if (DML_prelocking_strategy::handle_table(thd, prelocking_ctx, table_list,
+                                            need_prelocking))
+    return TRUE;
+
+  /*
+    normally we don't need to open FK-prelocked tables for RESTRICT,
+    MDL is enough. But under LOCK TABLES we have to open everything
+  */
+  for (TABLE_LIST *tl= *last; tl; tl= tl->next_global)
+    tl->open_strategy= TABLE_LIST::OPEN_NORMAL;
+
+  /* We rely on a caller to check that table is going to be changed. */
+  DBUG_ASSERT(table_list->lock_type >= TL_WRITE_ALLOW_WRITE);
+
+  return FALSE;
+}
+
+
+/**
+  Defines how prelocking algorithm for ALTER TABLE statement should handle
+  routines - do nothing as this statement is not supposed to call routines.
+
+  We still can end up in this method when someone tries
+  to define a foreign key referencing a view, and not just
+  a simple view, but one that uses stored routines.
+*/
+
+bool Alter_table_prelocking_strategy::
+handle_routine(THD *thd, Query_tables_list *prelocking_ctx,
+               Sroutine_hash_entry *rt, sp_head *sp, bool *need_prelocking)
+{
+  return FALSE;
+}
+
+
+/**
+  Defines how prelocking algorithm for ALTER TABLE statement should handle
+  table list elements.
+
+  Unlike in DML, we do not process triggers here.
+
+  @param[in]  thd              Thread context.
+  @param[in]  prelocking_ctx   Prelocking context of the statement.
+  @param[in]  table_list       Table list element for table.
+  @param[in]  sp               Routine body.
+  @param[out] need_prelocking  Set to TRUE if method detects that prelocking
+                               required, not changed otherwise.
+
+
+  @retval FALSE  Success.
+  @retval TRUE   Failure (OOM).
+*/
+
+bool Alter_table_prelocking_strategy::
+handle_table(THD *thd, Query_tables_list *prelocking_ctx,
+             TABLE_LIST *table_list, bool *need_prelocking)
+{
+  return FALSE;
+}
+
+
+/**
+  Defines how prelocking algorithm for ALTER TABLE statement
+  should handle view - do nothing. We don't need to add view
+  routines to the prelocking set in this case as view is not going
+  to be materialized.
+*/
+
+bool Alter_table_prelocking_strategy::
+handle_view(THD *thd, Query_tables_list *prelocking_ctx,
+            TABLE_LIST *table_list, bool *need_prelocking)
+{
+  return FALSE;
+}
+
+
+/**
+  Check that lock is ok for tables; Call start stmt if ok
+
+  @param thd             Thread handle.
+  @param prelocking_ctx  Prelocking context.
+  @param table_list      Table list element for table to be checked.
+
+  @retval FALSE - Ok.
+  @retval TRUE  - Error.
+*/
+
+static bool check_lock_and_start_stmt(THD *thd,
+                                      Query_tables_list *prelocking_ctx,
+                                      TABLE_LIST *table_list)
+{
+  int error;
+  thr_lock_type lock_type;
+  DBUG_ENTER("check_lock_and_start_stmt");
+
+  /*
+    Prelocking placeholder is not set for TABLE_LIST that
+    are directly used by TOP level statement.
+  */
+  DBUG_ASSERT(table_list->prelocking_placeholder == TABLE_LIST::PRELOCK_NONE);
+
+  /*
+    TL_WRITE_DEFAULT and TL_READ_DEFAULT are supposed to be parser only
+    types of locks so they should be converted to appropriate other types
+    to be passed to storage engine. The exact lock type passed to the
+    engine is important as, for example, InnoDB uses it to determine
+    what kind of row locks should be acquired when executing statement
+    in prelocked mode or under LOCK TABLES with @@innodb_table_locks = 0.
+
+    Last argument routine_modifies_data for read_lock_type_for_table()
+    is ignored, as prelocking placeholder will never be set here.
+  */
+  if (table_list->lock_type == TL_WRITE_DEFAULT)
+    lock_type= thd->update_lock_default;
+  else if (table_list->lock_type == TL_READ_DEFAULT)
+    lock_type= read_lock_type_for_table(thd, prelocking_ctx, table_list, true);
+  else
+    lock_type= table_list->lock_type;
+
+  if ((int) lock_type >= (int) TL_WRITE_ALLOW_WRITE &&
+      (int) table_list->table->reginfo.lock_type < (int) TL_WRITE_ALLOW_WRITE)
+  {
+    my_error(ER_TABLE_NOT_LOCKED_FOR_WRITE, MYF(0),
+             table_list->table->alias.c_ptr());
+    DBUG_RETURN(1);
+  }
+  if (unlikely((error= table_list->table->file->start_stmt(thd, lock_type))))
+  {
+    table_list->table->file->print_error(error, MYF(0));
+    DBUG_RETURN(1);
+  }
+
+  /*
+    Record in transaction state tracking
+  */
+  TRANSACT_TRACKER(add_trx_state(thd, lock_type,
+                                 table_list->table->file->has_transactions()));
+
+  DBUG_RETURN(0);
+}
+
+
+/**
+  @brief Open and lock one table
+
+  @param[in]    thd             thread handle
+  @param[in]    table_l         table to open is first table in this list
+  @param[in]    lock_type       lock to use for table
+  @param[in]    flags           options to be used while opening and locking
+                                table (see open_table(), mysql_lock_tables())
+  @param[in]    prelocking_strategy  Strategy which specifies how prelocking
+                                     algorithm should work for this statement.
+
+  @return       table
+    @retval     != NULL         OK, opened table returned
+    @retval     NULL            Error
+
+  @note
+    If ok, the following are also set:
+      table_list->lock_type 	lock_type
+      table_list->table		table
+
+  @note
+    If table_l is a list, not a single table, the list is temporarily
+    broken.
+
+  @detail
+    This function is meant as a replacement for open_ltable() when
+    MERGE tables can be opened. open_ltable() cannot open MERGE tables.
+
+    There may be more differences between open_n_lock_single_table() and
+    open_ltable(). One known difference is that open_ltable() does
+    neither call thd->decide_logging_format() nor handle some other logging
+    and locking issues because it does not call lock_tables().
+*/
+
+TABLE *open_n_lock_single_table(THD *thd, TABLE_LIST *table_l,
+                                thr_lock_type lock_type, uint flags,
+                                Prelocking_strategy *prelocking_strategy)
+{
+  TABLE_LIST *save_next_global;
+  DBUG_ENTER("open_n_lock_single_table");
+
+  /* Remember old 'next' pointer. */
+  save_next_global= table_l->next_global;
+  /* Break list. */
+  table_l->next_global= NULL;
+
+  /* Set requested lock type. */
+  table_l->lock_type= lock_type;
+  /* Allow to open real tables only. */
+  table_l->required_type= TABLE_TYPE_NORMAL;
+
+  /* Open the table. */
+  if (open_and_lock_tables(thd, table_l, FALSE, flags,
+                           prelocking_strategy))
+    table_l->table= NULL; /* Just to be sure. */
+
+  /* Restore list. */
+  table_l->next_global= save_next_global;
+
+  DBUG_RETURN(table_l->table);
+}
+
+
+/*
+  Open and lock one table
+
+  SYNOPSIS
+    open_ltable()
+    thd			Thread handler
+    table_list		Table to open is first table in this list
+    lock_type		Lock to use for open
+    lock_flags          Flags passed to mysql_lock_table
+
+  NOTE
+    This function doesn't do anything like SP/SF/views/triggers analysis done 
+    in open_table()/lock_tables(). It is intended for opening of only one
+    concrete table. And used only in special contexts.
+
+  RETURN VALUES
+    table		Opened table
+    0			Error
+  
+    If ok, the following are also set:
+      table_list->lock_type 	lock_type
+      table_list->table		table
+*/
+
+TABLE *open_ltable(THD *thd, TABLE_LIST *table_list, thr_lock_type lock_type,
+                   uint lock_flags)
+{
+  TABLE *table;
+  Open_table_context ot_ctx(thd, lock_flags);
+  bool error;
+  DBUG_ENTER("open_ltable");
+
+  /* Ignore temporary tables as they have already been opened. */
+  if (table_list->table)
+    DBUG_RETURN(table_list->table);
+
+  /* should not be used in a prelocked_mode context, see NOTE above */
+  DBUG_ASSERT(thd->locked_tables_mode < LTM_PRELOCKED);
+
+  THD_STAGE_INFO(thd, stage_opening_tables);
+  thd->current_tablenr= 0;
+  /* open_ltable can be used only for BASIC TABLEs */
+  table_list->required_type= TABLE_TYPE_NORMAL;
+
+  /* This function can't properly handle requests for such metadata locks. */
+  DBUG_ASSERT(table_list->mdl_request.type < MDL_SHARED_UPGRADABLE);
+
+  while ((error= open_table(thd, table_list, &ot_ctx)) &&
+         ot_ctx.can_recover_from_failed_open())
+  {
+    /*
+      Even though we have failed to open table we still need to
+      call release_transactional_locks() to release metadata locks which
+      might have been acquired successfully.
+    */
+    thd->mdl_context.rollback_to_savepoint(ot_ctx.start_of_statement_svp());
+    table_list->mdl_request.ticket= 0;
+    if (ot_ctx.recover_from_failed_open())
+      break;
+  }
+
+  if (likely(!error))
+  {
+    /*
+      We can't have a view or some special "open_strategy" in this function
+      so there should be a TABLE instance.
+    */
+    DBUG_ASSERT(table_list->table);
+    table= table_list->table;
+    if (table->file->ha_table_flags() & HA_CAN_MULTISTEP_MERGE)
+    {
+      /* A MERGE table must not come here. */
+      /* purecov: begin tested */
+      my_error(ER_WRONG_OBJECT, MYF(0), table->s->db.str,
+               table->s->table_name.str, "BASE TABLE");
+      table= 0;
+      goto end;
+      /* purecov: end */
+    }
+
+    table_list->lock_type= lock_type;
+    table->grant= table_list->grant;
+    if (thd->locked_tables_mode)
+    {
+      if (check_lock_and_start_stmt(thd, thd->lex, table_list))
+	table= 0;
+    }
+    else
+    {
+      DBUG_ASSERT(thd->lock == 0);	// You must lock everything at once
+      if ((table->reginfo.lock_type= lock_type) != TL_UNLOCK)
+	if (! (thd->lock= mysql_lock_tables(thd, &table_list->table, 1,
+                                            lock_flags)))
+        {
+          table= 0;
+        }
+    }
+  }
+  else
+    table= 0;
+
+end:
+  if (table == NULL)
+  {
+    if (!thd->in_sub_stmt)
+      trans_rollback_stmt(thd);
+    close_thread_tables(thd);
+  }
+  THD_STAGE_INFO(thd, stage_after_opening_tables);
+
+  thd_proc_info(thd, 0);
+  DBUG_RETURN(table);
+}
+
+
+/**
+  Open all tables in list, locks them and optionally process derived tables.
+
+  @param thd		      Thread context.
+  @param options              DDL options.
+  @param tables	              List of tables for open and locking.
+  @param derived              Whether to handle derived tables.
+  @param flags                Bitmap of options to be used to open and lock
+                              tables (see open_tables() and mysql_lock_tables()
+                              for details).
+  @param prelocking_strategy  Strategy which specifies how prelocking algorithm
+                              should work for this statement.
+
+  @note
+    The thr_lock locks will automatically be freed by
+    close_thread_tables().
+
+  @retval FALSE  OK.
+  @retval TRUE   Error
+*/
+
+bool open_and_lock_tables(THD *thd, const DDL_options_st &options,
+                          TABLE_LIST *tables,
+                          bool derived, uint flags,
+                          Prelocking_strategy *prelocking_strategy)
+{
+  uint counter;
+  MDL_savepoint mdl_savepoint= thd->mdl_context.mdl_savepoint();
+  DBUG_ENTER("open_and_lock_tables");
+  DBUG_PRINT("enter", ("derived handling: %d", derived));
+
+  if (open_tables(thd, options, &tables, &counter, flags, prelocking_strategy))
+    goto err;
+
+  DBUG_EXECUTE_IF("sleep_open_and_lock_after_open", {
+                  const char *old_proc_info= thd->proc_info;
+                  thd->proc_info= "DBUG sleep";
+                  my_sleep(6000000);
+                  thd->proc_info= old_proc_info;});
+
+  if (lock_tables(thd, tables, counter, flags))
+    goto err;
+
+  /* Don't read statistics tables when opening internal tables */
+  if (!(flags & MYSQL_OPEN_IGNORE_LOGGING_FORMAT))
+    (void) read_statistics_for_tables_if_needed(thd, tables);
+  
+  if (derived)
+  {
+    if (mysql_handle_derived(thd->lex, DT_INIT))
+      goto err;
+    if (thd->prepare_derived_at_open &&
+        (mysql_handle_derived(thd->lex, DT_PREPARE)))
+      goto err;
+  }
+
+  DBUG_RETURN(FALSE);
+err:
+  if (! thd->in_sub_stmt)
+    trans_rollback_stmt(thd);  /* Necessary if derived handling failed. */
+  close_thread_tables(thd);
+  /* Don't keep locks for a failed statement. */
+  thd->mdl_context.rollback_to_savepoint(mdl_savepoint);
+  DBUG_RETURN(TRUE);
+}
+
+
+/*
+  Open all tables in list and process derived tables
+
+  SYNOPSIS
+    open_normal_and_derived_tables
+    thd		- thread handler
+    tables	- list of tables for open
+    flags       - bitmap of flags to modify how the tables will be open:
+                  MYSQL_LOCK_IGNORE_FLUSH - open table even if someone has
+                  done a flush on it.
+    dt_phases   - set of flags to pass to the mysql_handle_derived
+
+  RETURN
+    FALSE - ok
+    TRUE  - error
+
+  NOTE 
+    This is to be used on prepare stage when you don't read any
+    data from the tables.
+*/
+
+bool open_normal_and_derived_tables(THD *thd, TABLE_LIST *tables, uint flags,
+                                    uint dt_phases)
+{
+  DML_prelocking_strategy prelocking_strategy;
+  uint counter;
+  MDL_savepoint mdl_savepoint= thd->mdl_context.mdl_savepoint();
+  DBUG_ENTER("open_normal_and_derived_tables");
+  if (open_tables(thd, &tables, &counter, flags, &prelocking_strategy) ||
+      mysql_handle_derived(thd->lex, dt_phases))
+    goto end;
+
+  DBUG_RETURN(0);
+end:
+  /*
+    No need to commit/rollback the statement transaction: it's
+    either not started or we're filling in an INFORMATION_SCHEMA
+    table on the fly, and thus mustn't manipulate with the
+    transaction of the enclosing statement.
+  */
+  DBUG_ASSERT(thd->transaction->stmt.is_empty() ||
+              (thd->state_flags & Open_tables_state::BACKUPS_AVAIL));
+  close_thread_tables(thd);
+  /* Don't keep locks for a failed statement. */
+  thd->mdl_context.rollback_to_savepoint(mdl_savepoint);
+
+  DBUG_RETURN(TRUE); /* purecov: inspected */
+}
+
+
+/**
+  Open a table to read its structure, e.g. for:
+  - SHOW FIELDS
+  - delayed SP variable data type definition: DECLARE a t1.a%TYPE
+
+  The flag MYSQL_OPEN_GET_NEW_TABLE is passed to make %TYPE work
+  in stored functions, as during a stored function call
+  (e.g. in a SELECT query) the tables referenced in %TYPE can already be locked,
+  and attempt to open it again would return an error in open_table().
+
+  The flag MYSQL_OPEN_GET_NEW_TABLE is not really needed for
+  SHOW FIELDS or for a "CALL sp()" statement, but it's not harmful,
+  so let's pass it unconditionally.
+*/
+
+bool open_tables_only_view_structure(THD *thd, TABLE_LIST *table_list,
+                                     bool can_deadlock)
+{
+  DBUG_ENTER("open_tables_only_view_structure");
+  /*
+    Let us set fake sql_command so views won't try to merge
+    themselves into main statement. If we don't do this,
+    SELECT * from information_schema.xxxx will cause problems.
+    SQLCOM_SHOW_FIELDS is used because it satisfies
+    'LEX::only_view_structure()'.
+  */
+  enum_sql_command save_sql_command= thd->lex->sql_command;
+  thd->lex->sql_command= SQLCOM_SHOW_FIELDS;
+  bool rc= (thd->open_temporary_tables(table_list) ||
+           open_normal_and_derived_tables(thd, table_list,
+                                          (MYSQL_OPEN_IGNORE_FLUSH |
+                                           MYSQL_OPEN_FORCE_SHARED_HIGH_PRIO_MDL |
+                                           MYSQL_OPEN_GET_NEW_TABLE |
+                                           (can_deadlock ?
+                                            MYSQL_OPEN_FAIL_ON_MDL_CONFLICT : 0)),
+                                          DT_INIT | DT_PREPARE));
+  /*
+    Restore old value of sql_command back as it is being looked at in
+    process_table() function.
+  */
+  thd->lex->sql_command= save_sql_command;
+  DBUG_RETURN(rc);
+}
+
+
+/*
+  Mark all real tables in the list as free for reuse.
+
+  SYNOPSIS
+    mark_real_tables_as_free_for_reuse()
+      thd   - thread context
+      table - head of the list of tables
+
+  DESCRIPTION
+    Marks all real tables in the list (i.e. not views, derived
+    or schema tables) as free for reuse.
+*/
+
+static void mark_real_tables_as_free_for_reuse(TABLE_LIST *table_list)
+{
+  TABLE_LIST *table;
+  DBUG_ENTER("mark_real_tables_as_free_for_reuse");
+
+  /*
+    We have to make two loops as HA_EXTRA_DETACH_CHILDREN may
+    remove items from the table list that we have to reset
+  */
+  for (table= table_list; table; table= table->next_global)
+  {
+    if (!table->placeholder())
+      table->table->query_id= 0;
+  }
+  for (table= table_list; table; table= table->next_global)
+  {
+    if (!table->placeholder())
+    {
+      /*
+        Detach children of MyISAMMRG tables used in
+        sub-statements, they will be reattached at open.
+        This has to be done in a separate loop to make sure
+        that children have had their query_id cleared.
+      */
+      table->table->file->extra(HA_EXTRA_DETACH_CHILDREN);
+    }
+  }
+  DBUG_VOID_RETURN;
+}
+
+int TABLE::fix_vcol_exprs(THD *thd)
+{
+  for (Field **vf= vfield; vf && *vf; vf++)
+    if (fix_session_vcol_expr(thd, (*vf)->vcol_info))
+      return 1;
+
+  for (Field **df= default_field; df && *df; df++)
+    if ((*df)->default_value &&
+        fix_session_vcol_expr(thd, (*df)->default_value))
+      return 1;
+
+  for (Virtual_column_info **cc= check_constraints; cc && *cc; cc++)
+    if (fix_session_vcol_expr(thd, (*cc)))
+      return 1;
+
+  return 0;
+}
+
+
+static bool fix_all_session_vcol_exprs(THD *thd, TABLE_LIST *tables)
+{
+  Security_context *save_security_ctx= thd->security_ctx;
+  TABLE_LIST *first_not_own= thd->lex->first_not_own_table();
+  DBUG_ENTER("fix_session_vcol_expr");
+
+  int error= 0;
+  for (TABLE_LIST *table= tables; table && table != first_not_own && !error;
+       table= table->next_global)
+  {
+    TABLE *t= table->table;
+    if (!table->placeholder() && t->s->vcols_need_refixing &&
+         table->lock_type >= TL_WRITE_ALLOW_WRITE)
+    {
+      Query_arena *stmt_backup= thd->stmt_arena;
+      if (thd->stmt_arena->is_conventional())
+        thd->stmt_arena= t->expr_arena;
+      if (table->security_ctx)
+        thd->security_ctx= table->security_ctx;
+
+      error= t->fix_vcol_exprs(thd);
+
+      thd->security_ctx= save_security_ctx;
+      thd->stmt_arena= stmt_backup;
+    }
+  }
+  DBUG_RETURN(error);
+}
+
+
+/**
+  Lock all tables in a list.
+
+  @param  thd           Thread handler
+  @param  tables        Tables to lock
+  @param  count         Number of opened tables
+  @param  flags         Options (see mysql_lock_tables() for details)
+
+  You can't call lock_tables() while holding thr_lock locks, as
+  this would break the dead-lock-free handling thr_lock gives us.
+  You must always get all needed locks at once.
+
+  If the query for which we are calling this function is marked as
+  requiring prelocking, this function will change
+  locked_tables_mode to LTM_PRELOCKED.
+
+  @retval FALSE         Success. 
+  @retval TRUE          A lock wait timeout, deadlock or out of memory.
+*/
+
+bool lock_tables(THD *thd, TABLE_LIST *tables, uint count, uint flags)
+{
+  TABLE_LIST *table, *first_not_own;
+  DBUG_ENTER("lock_tables");
+  /*
+    We can't meet statement requiring prelocking if we already
+    in prelocked mode.
+  */
+  DBUG_ASSERT(thd->locked_tables_mode <= LTM_LOCK_TABLES ||
+              !thd->lex->requires_prelocking());
+
+  if (!tables && !thd->lex->requires_prelocking())
+    DBUG_RETURN(0);
+
+  first_not_own= thd->lex->first_not_own_table();
+
+  /*
+    Check for thd->locked_tables_mode to avoid a redundant
+    and harmful attempt to lock the already locked tables again.
+    Checking for thd->lock is not enough in some situations. For example,
+    if a stored function contains
+    "drop table t3; create temporary t3 ..; insert into t3 ...;"
+    thd->lock may be 0 after drop tables, whereas locked_tables_mode
+    is still on. In this situation an attempt to lock temporary
+    table t3 will lead to a memory leak.
+  */
+  if (! thd->locked_tables_mode)
+  {
+    DBUG_ASSERT(thd->lock == 0);	// You must lock everything at once
+    TABLE **start,**ptr;
+    bool found_first_not_own= 0;
+
+    if (!(ptr=start=(TABLE**) thd->alloc(sizeof(TABLE*)*count)))
+      DBUG_RETURN(TRUE);
+
+    /*
+      Collect changes tables for table lock.
+      Mark own tables with query id as this is needed by
+      prepare_for_row_logging()
+    */
+    for (table= tables; table; table= table->next_global)
+    {
+      if (table == first_not_own)
+        found_first_not_own= 1;
+      if (!table->placeholder())
+      {
+        *(ptr++)= table->table;
+        if (!found_first_not_own)
+          table->table->query_id= thd->query_id;
+      }
+    }
+
+    DEBUG_SYNC(thd, "before_lock_tables_takes_lock");
+
+    if (! (thd->lock= mysql_lock_tables(thd, start, (uint) (ptr - start),
+                                        flags)))
+      DBUG_RETURN(TRUE);
+
+    DEBUG_SYNC(thd, "after_lock_tables_takes_lock");
+
+    if (thd->lex->requires_prelocking() &&
+        thd->lex->sql_command != SQLCOM_LOCK_TABLES)
+    {
+      /*
+        We just have done implicit LOCK TABLES, and now we have
+        to emulate first open_and_lock_tables() after it.
+
+        When open_and_lock_tables() is called for a single table out of
+        a table list, the 'next_global' chain is temporarily broken. We
+        may not find 'first_not_own' before the end of the "list".
+        Look for example at those places where open_n_lock_single_table()
+        is called. That function implements the temporary breaking of
+        a table list for opening a single table.
+      */
+      for (table= tables;
+           table && table != first_not_own;
+           table= table->next_global)
+      {
+        if (!table->placeholder())
+        {
+          if (check_lock_and_start_stmt(thd, thd->lex, table))
+          {
+            mysql_unlock_tables(thd, thd->lock);
+            thd->lock= 0;
+            DBUG_RETURN(TRUE);
+          }
+        }
+      }
+      /*
+        Let us mark all tables which don't belong to the statement itself,
+        and was marked as occupied during open_tables() as free for reuse.
+      */
+      mark_real_tables_as_free_for_reuse(first_not_own);
+      DBUG_PRINT("info",("locked_tables_mode= LTM_PRELOCKED"));
+      thd->enter_locked_tables_mode(LTM_PRELOCKED);
+    }
+  }
+  else
+  {
+    /*
+      When open_and_lock_tables() is called for a single table out of
+      a table list, the 'next_global' chain is temporarily broken. We
+      may not find 'first_not_own' before the end of the "list".
+      Look for example at those places where open_n_lock_single_table()
+      is called. That function implements the temporary breaking of
+      a table list for opening a single table.
+    */
+    for (table= tables;
+         table && table != first_not_own;
+         table= table->next_global)
+    {
+      if (table->placeholder())
+        continue;
+
+      table->table->query_id= thd->query_id;
+      /*
+        In a stored function or trigger we should ensure that we won't change
+        a table that is already used by the calling statement.
+      */
+      if (thd->locked_tables_mode >= LTM_PRELOCKED &&
+          table->lock_type >= TL_WRITE_ALLOW_WRITE)
+      {
+        for (TABLE* opentab= thd->open_tables; opentab; opentab= opentab->next)
+        {
+          if (table->table->s == opentab->s && opentab->query_id &&
+              table->table->query_id != opentab->query_id)
+          {
+            my_error(ER_CANT_UPDATE_USED_TABLE_IN_SF_OR_TRG, MYF(0),
+                     table->table->s->table_name.str);
+            DBUG_RETURN(TRUE);
+          }
+        }
+      }
+
+      if (check_lock_and_start_stmt(thd, thd->lex, table))
+      {
+	DBUG_RETURN(TRUE);
+      }
+    }
+    /*
+      If we are under explicit LOCK TABLES and our statement requires
+      prelocking, we should mark all "additional" tables as free for use
+      and enter prelocked mode.
+    */
+    if (thd->lex->requires_prelocking())
+    {
+      mark_real_tables_as_free_for_reuse(first_not_own);
+      DBUG_PRINT("info",
+                 ("thd->locked_tables_mode= LTM_PRELOCKED_UNDER_LOCK_TABLES"));
+      thd->locked_tables_mode= LTM_PRELOCKED_UNDER_LOCK_TABLES;
+    }
+  }
+
+  bool res= fix_all_session_vcol_exprs(thd, tables);
+  if (!res && !(flags & MYSQL_OPEN_IGNORE_LOGGING_FORMAT))
+    res= thd->decide_logging_format(tables);
+
+  DBUG_RETURN(res);
+}
+
+
+/*
+  Restart transaction for tables
+
+  This is used when we had to do an implicit commit after tables are opened
+  and want to restart transactions on tables.
+
+  This is used in case of:
+  LOCK TABLES xx
+  CREATE OR REPLACE TABLE xx;
+*/
+
+bool restart_trans_for_tables(THD *thd, TABLE_LIST *table)
+{
+  DBUG_ENTER("restart_trans_for_tables");
+
+  for (; table; table= table->next_global)
+  {
+    if (table->placeholder())
+      continue;
+
+    if (check_lock_and_start_stmt(thd, thd->lex, table))
+    {
+      DBUG_ASSERT(0);                           // Should never happen
+      DBUG_RETURN(TRUE);
+    }
+  }
+  DBUG_RETURN(FALSE);
+}
+
+
+/**
+  Prepare statement for reopening of tables and recalculation of set of
+  prelocked tables.
+
+  @param[in] thd         Thread context.
+  @param[in,out] tables  List of tables which we were trying to open
+                         and lock.
+  @param[in] start_of_statement_svp MDL savepoint which represents the set
+                         of metadata locks which the current transaction
+                         managed to acquire before execution of the current
+                         statement and to which we should revert before
+                         trying to reopen tables. NULL if no metadata locks
+                         were held and thus all metadata locks should be
+                         released.
+*/
+
+void close_tables_for_reopen(THD *thd, TABLE_LIST **tables,
+                             const MDL_savepoint &start_of_statement_svp)
+{
+  TABLE_LIST *first_not_own_table= thd->lex->first_not_own_table();
+  TABLE_LIST *tmp;
+
+  /*
+    If table list consists only from tables from prelocking set, table list
+    for new attempt should be empty, so we have to update list's root pointer.
+  */
+  if (first_not_own_table == *tables)
+    *tables= 0;
+  thd->lex->chop_off_not_own_tables();
+  /* Reset MDL tickets for procedures/functions */
+  for (Sroutine_hash_entry *rt=
+         (Sroutine_hash_entry*)thd->lex->sroutines_list.first;
+       rt; rt= rt->next)
+    rt->mdl_request.ticket= NULL;
+  sp_remove_not_own_routines(thd->lex);
+  for (tmp= *tables; tmp; tmp= tmp->next_global)
+  {
+    tmp->table= 0;
+    tmp->mdl_request.ticket= NULL;
+    /* We have to cleanup translation tables of views. */
+    tmp->cleanup_items();
+  }
+  /*
+    No need to commit/rollback the statement transaction: it's
+    either not started or we're filling in an INFORMATION_SCHEMA
+    table on the fly, and thus mustn't manipulate with the
+    transaction of the enclosing statement.
+  */
+  DBUG_ASSERT(thd->transaction->stmt.is_empty() ||
+              (thd->state_flags & Open_tables_state::BACKUPS_AVAIL));
+  close_thread_tables(thd);
+  thd->mdl_context.rollback_to_savepoint(start_of_statement_svp);
+}
+
+
+/*****************************************************************************
+* The following find_field_in_XXX procedures implement the core of the
+* name resolution functionality. The entry point to resolve a column name in a
+* list of tables is 'find_field_in_tables'. It calls 'find_field_in_table_ref'
+* for each table reference. In turn, depending on the type of table reference,
+* 'find_field_in_table_ref' calls one of the 'find_field_in_XXX' procedures
+* below specific for the type of table reference.
+******************************************************************************/
+
+/* Special Field pointers as return values of find_field_in_XXX functions. */
+Field *not_found_field= (Field*) 0x1;
+Field *view_ref_found= (Field*) 0x2; 
+
+#define WRONG_GRANT (Field*) -1
+
+static void update_field_dependencies(THD *thd, Field *field, TABLE *table)
+{
+  DBUG_ENTER("update_field_dependencies");
+  if (should_mark_column(thd->column_usage))
+  {
+    /*
+      We always want to register the used keys, as the column bitmap may have
+      been set for all fields (for example for view).
+    */
+    table->covering_keys.intersect(field->part_of_key);
+
+    if (thd->column_usage == MARK_COLUMNS_READ)
+    {
+      if (table->mark_column_with_deps(field))
+        DBUG_VOID_RETURN; // Field was already marked
+    }
+    else
+    {
+      if (bitmap_fast_test_and_set(table->write_set, field->field_index))
+      {
+        DBUG_PRINT("warning", ("Found duplicated field"));
+        thd->dup_field= field;
+        DBUG_VOID_RETURN;
+      }
+    }
+
+    table->used_fields++;
+  }
+  if (table->get_fields_in_item_tree)
+    field->flags|= GET_FIXED_FIELDS_FLAG;
+  DBUG_VOID_RETURN;
+}
+
+
+/*
+  Find a field by name in a view that uses merge algorithm.
+
+  SYNOPSIS
+    find_field_in_view()
+    thd				thread handler
+    table_list			view to search for 'name'
+    name			name of field
+    length			length of name
+    item_name                   name of item if it will be created (VIEW)
+    ref				expression substituted in VIEW should be passed
+                                using this reference (return view_ref_found)
+    register_tree_change        TRUE if ref is not stack variable and we
+                                need register changes in item tree
+
+  RETURN
+    0			field is not found
+    view_ref_found	found value in VIEW (real result is in *ref)
+    #			pointer to field - only for schema table fields
+*/
+
+static Field *
+find_field_in_view(THD *thd, TABLE_LIST *table_list,
+                   const char *name, size_t length,
+                   const char *item_name, Item **ref,
+                   bool register_tree_change)
+{
+  DBUG_ENTER("find_field_in_view");
+  DBUG_PRINT("enter",
+             ("view: '%s', field name: '%s', item name: '%s', ref %p",
+              table_list->alias.str, name, item_name, ref));
+  Field_iterator_view field_it;
+  field_it.set(table_list);
+  Query_arena *arena= 0, backup;  
+
+  for (; !field_it.end_of_fields(); field_it.next())
+  {
+    if (!my_strcasecmp(system_charset_info, field_it.name()->str, name))
+    {
+      // in PS use own arena or data will be freed after prepare
+      if (register_tree_change &&
+          thd->stmt_arena->is_stmt_prepare_or_first_stmt_execute())
+        arena= thd->activate_stmt_arena_if_needed(&backup);
+      /*
+        create_item() may, or may not create a new Item, depending on
+        the column reference. See create_view_field() for details.
+      */
+      Item *item= field_it.create_item(thd);
+      if (arena)
+        thd->restore_active_arena(arena, &backup);
+      
+      if (!item)
+        DBUG_RETURN(0);
+      if (!ref)
+        DBUG_RETURN((Field*) view_ref_found);
+      /*
+       *ref != NULL means that *ref contains the item that we need to
+       replace. If the item was aliased by the user, set the alias to
+       the replacing item.
+      */
+      if (*ref && !(*ref)->is_autogenerated_name())
+        item->set_name(thd, (*ref)->name);
+      if (register_tree_change)
+        thd->change_item_tree(ref, item);
+      else
+        *ref= item;
+      DBUG_RETURN((Field*) view_ref_found);
+    }
+  }
+  DBUG_RETURN(0);
+}
+
+
+/*
+  Find field by name in a NATURAL/USING join table reference.
+
+  SYNOPSIS
+    find_field_in_natural_join()
+    thd			 [in]  thread handler
+    table_ref            [in]  table reference to search
+    name		 [in]  name of field
+    length		 [in]  length of name
+    ref                  [in/out] if 'name' is resolved to a view field, ref is
+                               set to point to the found view field
+    register_tree_change [in]  TRUE if ref is not stack variable and we
+                               need register changes in item tree
+    actual_table         [out] the original table reference where the field
+                               belongs - differs from 'table_list' only for
+                               NATURAL/USING joins
+
+  DESCRIPTION
+    Search for a field among the result fields of a NATURAL/USING join.
+    Notice that this procedure is called only for non-qualified field
+    names. In the case of qualified fields, we search directly the base
+    tables of a natural join.
+
+  RETURN
+    NULL        if the field was not found
+    WRONG_GRANT if no access rights to the found field
+    #           Pointer to the found Field
+*/
+
+static Field *
+find_field_in_natural_join(THD *thd, TABLE_LIST *table_ref, const char *name, size_t length, Item **ref, bool register_tree_change,
+                           TABLE_LIST **actual_table)
+{
+  List_iterator_fast<Natural_join_column>
+    field_it(*(table_ref->join_columns));
+  Natural_join_column *nj_col, *curr_nj_col;
+  Field *UNINIT_VAR(found_field);
+  Query_arena *UNINIT_VAR(arena), backup;
+  DBUG_ENTER("find_field_in_natural_join");
+  DBUG_PRINT("enter", ("field name: '%s', ref %p",
+		       name, ref));
+  DBUG_ASSERT(table_ref->is_natural_join && table_ref->join_columns);
+  DBUG_ASSERT(*actual_table == NULL);
+
+  for (nj_col= NULL, curr_nj_col= field_it++; curr_nj_col; 
+       curr_nj_col= field_it++)
+  {
+    if (!my_strcasecmp(system_charset_info, curr_nj_col->name()->str, name))
+    {
+      if (nj_col)
+      {
+        my_error(ER_NON_UNIQ_ERROR, MYF(0), name, thd->where);
+        DBUG_RETURN(NULL);
+      }
+      nj_col= curr_nj_col;
+    }
+  }
+  if (!nj_col)
+    DBUG_RETURN(NULL);
+
+  if (nj_col->view_field)
+  {
+    Item *item;
+    if (register_tree_change)
+      arena= thd->activate_stmt_arena_if_needed(&backup);
+    /*
+      create_item() may, or may not create a new Item, depending on the
+      column reference. See create_view_field() for details.
+    */
+    item= nj_col->create_item(thd);
+    if (!item)
+      DBUG_RETURN(NULL);
+
+    /*
+     *ref != NULL means that *ref contains the item that we need to
+     replace. If the item was aliased by the user, set the alias to
+     the replacing item.
+     */
+    if (*ref && !(*ref)->is_autogenerated_name())
+      item->set_name(thd, (*ref)->name);
+    if (register_tree_change && arena)
+      thd->restore_active_arena(arena, &backup);
+
+    if (!item)
+      DBUG_RETURN(NULL);
+    DBUG_ASSERT(nj_col->table_field == NULL);
+    if (nj_col->table_ref->schema_table_reformed)
+    {
+      /*
+        Translation table items are always Item_fields and fixed
+        already('mysql_schema_table' function). So we can return
+        ->field. It is used only for 'show & where' commands.
+      */
+      DBUG_RETURN(((Item_field*) (nj_col->view_field->item))->field);
+    }
+    if (register_tree_change)
+      thd->change_item_tree(ref, item);
+    else
+      *ref= item;
+    found_field= (Field*) view_ref_found;
+  }
+  else
+  {
+    /* This is a base table. */
+    DBUG_ASSERT(nj_col->view_field == NULL);
+    Item *ref= 0;
+    /*
+      This fix_fields is not necessary (initially this item is fixed by
+      the Item_field constructor; after reopen_tables the Item_func_eq
+      calls fix_fields on that item), it's just a check during table
+      reopening for columns that was dropped by the concurrent connection.
+    */
+    if (nj_col->table_field->fix_fields_if_needed(thd, &ref))
+    {
+      DBUG_PRINT("info", ("column '%s' was dropped by the concurrent connection",
+                          nj_col->table_field->name.str));
+      DBUG_RETURN(NULL);
+    }
+    DBUG_ASSERT(ref == 0);                      // Should not have changed
+    DBUG_ASSERT(nj_col->table_ref->table == nj_col->table_field->field->table);
+    found_field= nj_col->table_field->field;
+    update_field_dependencies(thd, found_field, nj_col->table_ref->table);
+  }
+
+  *actual_table= nj_col->table_ref;
+  
+  DBUG_RETURN(found_field);
+}
+
+
+/*
+  Find field by name in a base table or a view with temp table algorithm.
+
+  The caller is expected to check column-level privileges.
+
+  SYNOPSIS
+    find_field_in_table()
+    thd				thread handler
+    table			table where to search for the field
+    name			name of field
+    length			length of name
+    allow_rowid			do allow finding of "_rowid" field?
+    cached_field_index_ptr	cached position in field list (used to speedup
+                                lookup for fields in prepared tables)
+
+  RETURN
+    0	field is not found
+    #	pointer to field
+*/
+
+Field *
+find_field_in_table(THD *thd, TABLE *table, const char *name, size_t length,
+                    bool allow_rowid, uint *cached_field_index_ptr)
+{
+  Field *field;
+  uint cached_field_index= *cached_field_index_ptr;
+  DBUG_ENTER("find_field_in_table");
+  DBUG_PRINT("enter", ("table: '%s', field name: '%s'", table->alias.c_ptr(),
+                       name));
+
+  /* We assume here that table->field < NO_CACHED_FIELD_INDEX = UINT_MAX */
+  if (cached_field_index < table->s->fields &&
+      !my_strcasecmp(system_charset_info,
+                     table->field[cached_field_index]->field_name.str, name))
+    field= table->field[cached_field_index];
+  else
+  {
+    LEX_CSTRING fname= {name, length};
+    field= table->find_field_by_name(&fname);
+  }
+
+  if (field)
+  {
+    if (field->invisible == INVISIBLE_FULL &&
+        DBUG_EVALUATE_IF("test_completely_invisible", 0, 1))
+      DBUG_RETURN((Field*)0);
+
+    if (field->invisible == INVISIBLE_SYSTEM &&
+        thd->column_usage != MARK_COLUMNS_READ &&
+        thd->column_usage != COLUMNS_READ)
+      DBUG_RETURN((Field*)0);
+  }
+  else
+  {
+    if (!allow_rowid ||
+        my_strcasecmp(system_charset_info, name, "_rowid") ||
+        table->s->rowid_field_offset == 0)
+      DBUG_RETURN((Field*) 0);
+    field= table->field[table->s->rowid_field_offset-1];
+  }
+  *cached_field_index_ptr= field->field_index;
+
+  update_field_dependencies(thd, field, table);
+
+  DBUG_RETURN(field);
+}
+
+
+/*
+  Find field in a table reference.
+
+  SYNOPSIS
+    find_field_in_table_ref()
+    thd			   [in]  thread handler
+    table_list		   [in]  table reference to search
+    name		   [in]  name of field
+    length		   [in]  field length of name
+    item_name              [in]  name of item if it will be created (VIEW)
+    db_name                [in]  optional database name that qualifies the
+    table_name             [in]  optional table name that qualifies the field
+                                 0 for non-qualified field in natural joins
+    ref		       [in/out] if 'name' is resolved to a view field, ref
+                                 is set to point to the found view field
+    check_privileges       [in]  check privileges
+    allow_rowid		   [in]  do allow finding of "_rowid" field?
+    cached_field_index_ptr [in]  cached position in field list (used to
+                                 speedup lookup for fields in prepared tables)
+    register_tree_change   [in]  TRUE if ref is not stack variable and we
+                                 need register changes in item tree
+    actual_table           [out] the original table reference where the field
+                                 belongs - differs from 'table_list' only for
+                                 NATURAL_USING joins.
+
+  DESCRIPTION
+    Find a field in a table reference depending on the type of table
+    reference. There are three types of table references with respect
+    to the representation of their result columns:
+    - an array of Field_translator objects for MERGE views and some
+      information_schema tables,
+    - an array of Field objects (and possibly a name hash) for stored
+      tables,
+    - a list of Natural_join_column objects for NATURAL/USING joins.
+    This procedure detects the type of the table reference 'table_list'
+    and calls the corresponding search routine.
+
+    The routine checks column-level privieleges for the found field.
+
+  RETURN
+    0			field is not found
+    view_ref_found	found value in VIEW (real result is in *ref)
+    #			pointer to field
+*/
+
+Field *
+find_field_in_table_ref(THD *thd, TABLE_LIST *table_list,
+                        const char *name, size_t length,
+                        const char *item_name, const char *db_name,
+                        const char *table_name, Item **ref,
+                        bool check_privileges, bool allow_rowid,
+                        uint *cached_field_index_ptr,
+                        bool register_tree_change, TABLE_LIST **actual_table)
+{
+  Field *fld;
+  DBUG_ENTER("find_field_in_table_ref");
+  DBUG_ASSERT(table_list->alias.str);
+  DBUG_ASSERT(name);
+  DBUG_ASSERT(item_name);
+  DBUG_PRINT("enter",
+             ("table: '%s'  field name: '%s'  item name: '%s'  ref %p",
+              table_list->alias.str, name, item_name, ref));
+
+  /*
+    Check that the table and database that qualify the current field name
+    are the same as the table reference we are going to search for the field.
+
+    Exclude from the test below nested joins because the columns in a
+    nested join generally originate from different tables. Nested joins
+    also have no table name, except when a nested join is a merge view
+    or an information schema table.
+
+    We include explicitly table references with a 'field_translation' table,
+    because if there are views over natural joins we don't want to search
+    inside the view, but we want to search directly in the view columns
+    which are represented as a 'field_translation'.
+
+    tables->db.str may be 0 if we are preparing a statement
+    db_name is 0 if item doesn't have a db name
+    table_name is 0 if item doesn't have a specified table_name
+  */
+  if (db_name && !db_name[0])
+    db_name= 0;                                 // Simpler test later
+
+  if (/* Exclude nested joins. */
+      (!table_list->nested_join ||
+       /* Include merge views and information schema tables. */
+       table_list->field_translation) &&
+      /*
+        Test if the field qualifiers match the table reference we plan
+        to search.
+      */
+      table_name && table_name[0] &&
+      (my_strcasecmp(table_alias_charset, table_list->alias.str, table_name) ||
+       (db_name && (!table_list->db.str || !table_list->db.str[0])) ||
+       (db_name && table_list->db.str && table_list->db.str[0] &&
+        (table_list->schema_table ?
+         my_strcasecmp(system_charset_info, db_name, table_list->db.str) :
+         strcmp(db_name, table_list->db.str)))))
+    DBUG_RETURN(0);
+
+  /*
+    Don't allow usage of fields in sequence table that is opened as part of
+    NEXT VALUE for sequence_name
+  */
+  if (table_list->sequence)
+    DBUG_RETURN(0);
+
+  *actual_table= NULL;
+
+  if (table_list->field_translation)
+  {
+    /* 'table_list' is a view or an information schema table. */
+    if ((fld= find_field_in_view(thd, table_list, name, length, item_name, ref,
+                                 register_tree_change)))
+      *actual_table= table_list;
+  }
+  else if (!table_list->nested_join)
+  {
+    /* 'table_list' is a stored table. */
+    DBUG_ASSERT(table_list->table);
+    if ((fld= find_field_in_table(thd, table_list->table, name, length,
+                                  allow_rowid,
+                                  cached_field_index_ptr)))
+      *actual_table= table_list;
+  }
+  else
+  {
+    /*
+      'table_list' is a NATURAL/USING join, or an operand of such join that
+      is a nested join itself.
+
+      If the field name we search for is qualified, then search for the field
+      in the table references used by NATURAL/USING the join.
+    */
+    if (table_name && table_name[0])
+    {
+      List_iterator<TABLE_LIST> it(table_list->nested_join->join_list);
+      TABLE_LIST *table;
+      while ((table= it++))
+      {
+        if ((fld= find_field_in_table_ref(thd, table, name, length, item_name,
+                                          db_name, table_name, ref,
+                                          check_privileges, allow_rowid,
+                                          cached_field_index_ptr,
+                                          register_tree_change, actual_table)))
+          DBUG_RETURN(fld);
+      }
+      DBUG_RETURN(0);
+    }
+    /*
+      Non-qualified field, search directly in the result columns of the
+      natural join. The condition of the outer IF is true for the top-most
+      natural join, thus if the field is not qualified, we will search
+      directly the top-most NATURAL/USING join.
+    */
+    fld= find_field_in_natural_join(thd, table_list, name, length, ref,
+                                    register_tree_change, actual_table);
+  }
+
+  if (fld)
+  {
+#ifndef NO_EMBEDDED_ACCESS_CHECKS
+    /* Check if there are sufficient access rights to the found field. */
+    if (check_privileges &&
+        !table_list->is_derived() &&
+        check_column_grant_in_table_ref(thd, *actual_table, name, length, fld))
+      fld= WRONG_GRANT;
+    else
+#endif
+      if (should_mark_column(thd->column_usage))
+      {
+        /*
+          Get rw_set correct for this field so that the handler
+          knows that this field is involved in the query and gets
+          retrieved/updated
+         */
+        Field *field_to_set= NULL;
+        if (fld == view_ref_found)
+        {
+          if (!ref)
+            DBUG_RETURN(fld);
+          Item *it= (*ref)->real_item();
+          if (it->type() == Item::FIELD_ITEM)
+            field_to_set= ((Item_field*)it)->field;
+          else
+          {
+            if (thd->column_usage == MARK_COLUMNS_READ)
+              it->walk(&Item::register_field_in_read_map, 0, 0);
+            else
+              it->walk(&Item::register_field_in_write_map, 0, 0);
+          }
+        }
+        else
+          field_to_set= fld;
+        if (field_to_set)
+        {
+          TABLE *table= field_to_set->table;
+          DBUG_ASSERT(table);
+          if (thd->column_usage == MARK_COLUMNS_READ)
+            field_to_set->register_field_in_read_map();
+          else
+            bitmap_set_bit(table->write_set, field_to_set->field_index);
+        }
+      }
+  }
+  DBUG_RETURN(fld);
+}
+
+
+/*
+  Find field in table, no side effects, only purpose is to check for field
+  in table object and get reference to the field if found.
+
+  SYNOPSIS
+  find_field_in_table_sef()
+
+  table                         table where to find
+  name                          Name of field searched for
+
+  RETURN
+    0                   field is not found
+    #                   pointer to field
+*/
+
+Field *find_field_in_table_sef(TABLE *table, const char *name)
+{
+  Field **field_ptr;
+  if (table->s->name_hash.records)
+  {
+    field_ptr= (Field**)my_hash_search(&table->s->name_hash,(uchar*) name,
+                                       strlen(name));
+    if (field_ptr)
+    {
+      /*
+        field_ptr points to field in TABLE_SHARE. Convert it to the matching
+        field in table
+      */
+      field_ptr= (table->field + (field_ptr - table->s->field));
+    }
+  }
+  else
+  {
+    if (!(field_ptr= table->field))
+      return (Field *)0;
+    for (; *field_ptr; ++field_ptr)
+      if (!my_strcasecmp(system_charset_info, (*field_ptr)->field_name.str,
+                         name))
+        break;
+  }
+  if (field_ptr)
+    return *field_ptr;
+  else
+    return (Field *)0;
+}
+
+
+/*
+  Find field in table list.
+
+  SYNOPSIS
+    find_field_in_tables()
+    thd			  pointer to current thread structure
+    item		  field item that should be found
+    first_table           list of tables to be searched for item
+    last_table            end of the list of tables to search for item. If NULL
+                          then search to the end of the list 'first_table'.
+    ref			  if 'item' is resolved to a view field, ref is set to
+                          point to the found view field
+    report_error	  Degree of error reporting:
+                          - IGNORE_ERRORS then do not report any error
+                          - IGNORE_EXCEPT_NON_UNIQUE report only non-unique
+                            fields, suppress all other errors
+                          - REPORT_EXCEPT_NON_UNIQUE report all other errors
+                            except when non-unique fields were found
+                          - REPORT_ALL_ERRORS
+    check_privileges      need to check privileges
+    register_tree_change  TRUE if ref is not a stack variable and we
+                          to need register changes in item tree
+
+  RETURN VALUES
+    0			If error: the found field is not unique, or there are
+                        no sufficient access priviliges for the found field,
+                        or the field is qualified with non-existing table.
+    not_found_field	The function was called with report_error ==
+                        (IGNORE_ERRORS || IGNORE_EXCEPT_NON_UNIQUE) and a
+			field was not found.
+    view_ref_found	View field is found, item passed through ref parameter
+    found field         If a item was resolved to some field
+*/
+
+Field *
+find_field_in_tables(THD *thd, Item_ident *item,
+                     TABLE_LIST *first_table, TABLE_LIST *last_table,
+		     Item **ref, find_item_error_report_type report_error,
+                     bool check_privileges, bool register_tree_change)
+{
+  Field *found=0;
+  const char *db= item->db_name.str;
+  const char *table_name= item->table_name.str;
+  const char *name= item->field_name.str;
+  size_t length= item->field_name.length;
+  char name_buff[SAFE_NAME_LEN+1];
+  TABLE_LIST *cur_table= first_table;
+  TABLE_LIST *actual_table;
+  bool allow_rowid;
+
+  if (!table_name || !table_name[0])
+  {
+    table_name= 0;                              // For easier test
+    db= 0;
+  }
+
+  allow_rowid= table_name || (cur_table && !cur_table->next_local);
+
+  if (item->cached_table)
+  {
+    DBUG_PRINT("info", ("using cached table"));
+    /*
+      This shortcut is used by prepared statements. We assume that
+      TABLE_LIST *first_table is not changed during query execution (which
+      is true for all queries except RENAME but luckily RENAME doesn't
+      use fields...) so we can rely on reusing pointer to its member.
+      With this optimization we also miss case when addition of one more
+      field makes some prepared query ambiguous and so erroneous, but we
+      accept this trade off.
+    */
+    TABLE_LIST *table_ref= item->cached_table;
+    /*
+      The condition (table_ref->view == NULL) ensures that we will call
+      find_field_in_table even in the case of information schema tables
+      when table_ref->field_translation != NULL.
+      */
+    if (table_ref->table && !table_ref->view &&
+        (!table_ref->is_merged_derived() ||
+         (!table_ref->is_multitable() && table_ref->merged_for_insert)))
+    {
+
+      found= find_field_in_table(thd, table_ref->table, name, length,
+                                 TRUE, &(item->cached_field_index));
+#ifndef NO_EMBEDDED_ACCESS_CHECKS
+      /* Check if there are sufficient access rights to the found field. */
+      if (found && check_privileges &&
+          check_column_grant_in_table_ref(thd, table_ref, name, length, found))
+        found= WRONG_GRANT;
+#endif
+    }
+    else
+      found= find_field_in_table_ref(thd, table_ref, name, length, item->name.str,
+                                     NULL, NULL, ref, check_privileges,
+                                     TRUE, &(item->cached_field_index),
+                                     register_tree_change,
+                                     &actual_table);
+    if (found)
+    {
+      if (found == WRONG_GRANT)
+	return (Field*) 0;
+
+      /*
+        Only views fields should be marked as dependent, not an underlying
+        fields.
+      */
+      if (!table_ref->belong_to_view &&
+          !table_ref->belong_to_derived)
+      {
+        SELECT_LEX *current_sel= item->context->select_lex;
+        SELECT_LEX *last_select= table_ref->select_lex;
+        bool all_merged= TRUE;
+        for (SELECT_LEX *sl= current_sel; sl && sl!=last_select;
+             sl=sl->outer_select())
+        {
+          Item_in_subselect *in_subs=
+            sl->master_unit()->item->get_IN_subquery();
+          if (in_subs &&
+              in_subs->substype() == Item_subselect::IN_SUBS &&
+              in_subs->test_strategy(SUBS_SEMI_JOIN))
+          {
+            continue;
+          }
+          all_merged= FALSE;
+          break;
+        }
+        /*
+          If the field was an outer referencee, mark all selects using this
+          sub query as dependent on the outer query
+        */
+        if (!all_merged && current_sel != last_select)
+        {
+          mark_select_range_as_dependent(thd, last_select, current_sel,
+                                         found, *ref, item, true);
+        }
+      }
+      return found;
+    }
+  }
+  else
+    item->can_be_depended= TRUE;
+
+  if (db && lower_case_table_names)
+  {
+    /*
+      convert database to lower case for comparison.
+      We can't do this in Item_field as this would change the
+      'name' of the item which may be used in the select list
+    */
+    strmake_buf(name_buff, db);
+    my_casedn_str(files_charset_info, name_buff);
+    db= name_buff;
+  }
+
+  if (last_table)
+    last_table= last_table->next_name_resolution_table;
+
+  for (; cur_table != last_table ;
+       cur_table= cur_table->next_name_resolution_table)
+  {
+    Field *cur_field= find_field_in_table_ref(thd, cur_table, name, length,
+                                              item->name.str, db, table_name, ref,
+                                              (thd->lex->sql_command ==
+                                               SQLCOM_SHOW_FIELDS)
+                                              ? false : check_privileges,
+                                              allow_rowid,
+                                              &(item->cached_field_index),
+                                              register_tree_change,
+                                              &actual_table);
+    if (cur_field)
+    {
+      if (cur_field == WRONG_GRANT)
+      {
+        if (thd->lex->sql_command != SQLCOM_SHOW_FIELDS)
+          return (Field*) 0;
+
+        thd->clear_error();
+        cur_field= find_field_in_table_ref(thd, cur_table, name, length,
+                                           item->name.str, db, table_name, ref,
+                                           false,
+                                           allow_rowid,
+                                           &(item->cached_field_index),
+                                           register_tree_change,
+                                           &actual_table);
+        if (cur_field)
+        {
+          Field *nf=new Field_null(NULL,0,Field::NONE,
+                                   &cur_field->field_name,
+                                   &my_charset_bin);
+          nf->init(cur_table->table);
+          cur_field= nf;
+        }
+      }
+
+      /*
+        Store the original table of the field, which may be different from
+        cur_table in the case of NATURAL/USING join.
+      */
+      item->cached_table= (!actual_table->cacheable_table || found) ?
+                          0 : actual_table;
+
+      DBUG_ASSERT(thd->where);
+      /*
+        If we found a fully qualified field we return it directly as it can't
+        have duplicates.
+       */
+      if (db)
+        return cur_field;
+      
+      if (unlikely(found))
+      {
+        if (report_error == REPORT_ALL_ERRORS ||
+            report_error == IGNORE_EXCEPT_NON_UNIQUE)
+          my_error(ER_NON_UNIQ_ERROR, MYF(0),
+                   table_name ? item->full_name() : name, thd->where);
+        return (Field*) 0;
+      }
+      found= cur_field;
+    }
+  }
+
+  if (likely(found))
+    return found;
+  
+  /*
+    If the field was qualified and there were no tables to search, issue
+    an error that an unknown table was given. The situation is detected
+    as follows: if there were no tables we wouldn't go through the loop
+    and cur_table wouldn't be updated by the loop increment part, so it
+    will be equal to the first table.
+  */
+  if (table_name && (cur_table == first_table) &&
+      (report_error == REPORT_ALL_ERRORS ||
+       report_error == REPORT_EXCEPT_NON_UNIQUE))
+  {
+    char buff[SAFE_NAME_LEN*2 + 2];
+    if (db && db[0])
+    {
+      strxnmov(buff,sizeof(buff)-1,db,".",table_name,NullS);
+      table_name=buff;
+    }
+    my_error(ER_UNKNOWN_TABLE, MYF(0), table_name, thd->where);
+  }
+  else
+  {
+    if (report_error == REPORT_ALL_ERRORS ||
+        report_error == REPORT_EXCEPT_NON_UNIQUE)
+      my_error(ER_BAD_FIELD_ERROR, MYF(0), item->full_name(), thd->where);
+    else
+      found= not_found_field;
+  }
+  return found;
+}
+
+
+/*
+  Find Item in list of items (find_field_in_tables analog)
+
+  TODO
+    is it better return only counter?
+
+  SYNOPSIS
+    find_item_in_list()
+    find			Item to find
+    items			List of items
+    counter			To return number of found item
+    report_error
+      REPORT_ALL_ERRORS		report errors, return 0 if error
+      REPORT_EXCEPT_NOT_FOUND	Do not report 'not found' error and
+				return not_found_item, report other errors,
+				return 0
+      IGNORE_ERRORS		Do not report errors, return 0 if error
+    resolution                  Set to the resolution type if the item is found 
+                                (it says whether the item is resolved 
+                                 against an alias name,
+                                 or as a field name without alias,
+                                 or as a field hidden by alias,
+                                 or ignoring alias)
+    limit                       How many items in the list to check
+                                (if limit==0 then all items are to be checked)
+                                
+  RETURN VALUES
+    0			Item is not found or item is not unique,
+			error message is reported
+    not_found_item	Function was called with
+			report_error == REPORT_EXCEPT_NOT_FOUND and
+			item was not found. No error message was reported
+                        found field
+*/
+
+/* Special Item pointer to serve as a return value from find_item_in_list(). */
+Item **not_found_item= (Item**) 0x1;
+
+
+Item **
+find_item_in_list(Item *find, List<Item> &items, uint *counter,
+                  find_item_error_report_type report_error,
+                  enum_resolution_type *resolution, uint limit)
+{
+  List_iterator<Item> li(items);
+  uint n_items= limit == 0 ? items.elements : limit;
+  Item **found=0, **found_unaliased= 0, *item;
+  const char *db_name=0;
+  const LEX_CSTRING *field_name= 0;
+  const char *table_name=0;
+  bool found_unaliased_non_uniq= 0;
+  /*
+    true if the item that we search for is a valid name reference
+    (and not an item that happens to have a name).
+  */
+  bool is_ref_by_name= 0;
+  uint unaliased_counter= 0;
+
+  *resolution= NOT_RESOLVED;
+
+  is_ref_by_name= (find->type() == Item::FIELD_ITEM  || 
+                   find->type() == Item::REF_ITEM);
+  if (is_ref_by_name)
+  {
+    field_name= &((Item_ident*) find)->field_name;
+    table_name= ((Item_ident*) find)->table_name.str;
+    db_name=    ((Item_ident*) find)->db_name.str;
+  }
+
+  for (uint i= 0; i < n_items; i++)
+  {
+    item= li++;
+    if (field_name && field_name->str &&
+        (item->real_item()->type() == Item::FIELD_ITEM ||
+         ((item->type() == Item::REF_ITEM) &&
+          (((Item_ref *)item)->ref_type() == Item_ref::VIEW_REF))))
+    {
+      Item_ident *item_field= (Item_ident*) item;
+
+      /*
+	In case of group_concat() with ORDER BY condition in the QUERY
+	item_field can be field of temporary table without item name 
+	(if this field created from expression argument of group_concat()),
+	=> we have to check presence of name before compare
+      */ 
+      if (unlikely(!item_field->name.str))
+        continue;
+
+      if (table_name)
+      {
+        /*
+          If table name is specified we should find field 'field_name' in
+          table 'table_name'. According to SQL-standard we should ignore
+          aliases in this case.
+
+          Since we should NOT prefer fields from the select list over
+          other fields from the tables participating in this select in
+          case of ambiguity we have to do extra check outside this function.
+
+          We use strcmp for table names and database names as these may be
+          case sensitive. In cases where they are not case sensitive, they
+          are always in lower case.
+
+	  item_field->field_name and item_field->table_name can be 0x0 if
+	  item is not fix_field()'ed yet.
+        */
+        if (item_field->field_name.str && item_field->table_name.str &&
+	    !lex_string_cmp(system_charset_info, &item_field->field_name,
+                            field_name) &&
+            !my_strcasecmp(table_alias_charset, item_field->table_name.str,
+                           table_name) &&
+            (!db_name || (item_field->db_name.str &&
+                          !strcmp(item_field->db_name.str, db_name))))
+        {
+          if (found_unaliased)
+          {
+            if ((*found_unaliased)->eq(item, 0))
+              continue;
+            /*
+              Two matching fields in select list.
+              We already can bail out because we are searching through
+              unaliased names only and will have duplicate error anyway.
+            */
+            if (report_error != IGNORE_ERRORS)
+              my_error(ER_NON_UNIQ_ERROR, MYF(0),
+                       find->full_name(), current_thd->where);
+            return (Item**) 0;
+          }
+          found_unaliased= li.ref();
+          unaliased_counter= i;
+          *resolution= RESOLVED_IGNORING_ALIAS;
+          if (db_name)
+            break;                              // Perfect match
+        }
+      }
+      else
+      {
+        bool fname_cmp= lex_string_cmp(system_charset_info,
+                                       &item_field->field_name,
+                                       field_name);
+        if (!lex_string_cmp(system_charset_info,
+                            &item_field->name, field_name))
+        {
+          /*
+            If table name was not given we should scan through aliases
+            and non-aliased fields first. We are also checking unaliased
+            name of the field in then next  else-if, to be able to find
+            instantly field (hidden by alias) if no suitable alias or
+            non-aliased field was found.
+          */
+          if (found)
+          {
+            if ((*found)->eq(item, 0))
+              continue;                           // Same field twice
+            if (report_error != IGNORE_ERRORS)
+              my_error(ER_NON_UNIQ_ERROR, MYF(0),
+                       find->full_name(), current_thd->where);
+            return (Item**) 0;
+          }
+          found= li.ref();
+          *counter= i;
+          *resolution= fname_cmp ? RESOLVED_AGAINST_ALIAS:
+	                           RESOLVED_WITH_NO_ALIAS;
+        }
+        else if (!fname_cmp)
+        {
+          /*
+            We will use non-aliased field or react on such ambiguities only if
+            we won't be able to find aliased field.
+            Again if we have ambiguity with field outside of select list
+            we should prefer fields from select list.
+          */
+          if (found_unaliased)
+          {
+            if ((*found_unaliased)->eq(item, 0))
+              continue;                           // Same field twice
+            found_unaliased_non_uniq= 1;
+          }
+          found_unaliased= li.ref();
+          unaliased_counter= i;
+        }
+      }
+    }
+    else if (!table_name)
+    { 
+      if (is_ref_by_name && find->name.str && item->name.str &&
+          find->name.length == item->name.length &&
+	  !lex_string_cmp(system_charset_info, &item->name, &find->name))
+      {
+        found= li.ref();
+        *counter= i;
+        *resolution= RESOLVED_AGAINST_ALIAS;
+        break;
+      }
+      else if (find->eq(item,0))
+      {
+        found= li.ref();
+        *counter= i;
+        *resolution= RESOLVED_IGNORING_ALIAS;
+        break;
+      }
+    }
+  }
+
+  if (likely(found))
+    return found;
+
+  if (unlikely(found_unaliased_non_uniq))
+  {
+    if (report_error != IGNORE_ERRORS)
+      my_error(ER_NON_UNIQ_ERROR, MYF(0),
+               find->full_name(), current_thd->where);
+    return (Item **) 0;
+  }
+  if (found_unaliased)
+  {
+    found= found_unaliased;
+    *counter= unaliased_counter;
+    *resolution= RESOLVED_BEHIND_ALIAS;
+  }
+
+  if (found)
+    return found;
+
+  if (report_error != REPORT_EXCEPT_NOT_FOUND)
+  {
+    if (report_error == REPORT_ALL_ERRORS)
+      my_error(ER_BAD_FIELD_ERROR, MYF(0),
+               find->full_name(), current_thd->where);
+    return (Item **) 0;
+  }
+  else
+    return (Item **) not_found_item;
+}
+
+
+/*
+  Test if a string is a member of a list of strings.
+
+  SYNOPSIS
+    test_if_string_in_list()
+    find      the string to look for
+    str_list  a list of strings to be searched
+
+  DESCRIPTION
+    Sequentially search a list of strings for a string, and test whether
+    the list contains the same string.
+
+  RETURN
+    TRUE  if find is in str_list
+    FALSE otherwise
+*/
+
+static bool
+test_if_string_in_list(const char *find, List<String> *str_list)
+{
+  List_iterator<String> str_list_it(*str_list);
+  String *curr_str;
+  size_t find_length= strlen(find);
+  while ((curr_str= str_list_it++))
+  {
+    if (find_length != curr_str->length())
+      continue;
+    if (!my_strcasecmp(system_charset_info, find, curr_str->ptr()))
+      return TRUE;
+  }
+  return FALSE;
+}
+
+
+/*
+  Create a new name resolution context for an item so that it is
+  being resolved in a specific table reference.
+
+  SYNOPSIS
+    set_new_item_local_context()
+    thd        pointer to current thread
+    item       item for which new context is created and set
+    table_ref  table ref where an item showld be resolved
+
+  DESCRIPTION
+    Create a new name resolution context for an item, so that the item
+    is resolved only the supplied 'table_ref'.
+
+  RETURN
+    FALSE  if all OK
+    TRUE   otherwise
+*/
+
+static bool
+set_new_item_local_context(THD *thd, Item_ident *item, TABLE_LIST *table_ref)
+{
+  Name_resolution_context *context;
+  if (!(context= new (thd->mem_root) Name_resolution_context))
+    return TRUE;
+  context->init();
+  context->first_name_resolution_table=
+    context->last_name_resolution_table= table_ref;
+  item->context= context;
+  return FALSE;
+}
+
+
+/*
+  Find and mark the common columns of two table references.
+
+  SYNOPSIS
+    mark_common_columns()
+    thd                [in] current thread
+    table_ref_1        [in] the first (left) join operand
+    table_ref_2        [in] the second (right) join operand
+    using_fields       [in] if the join is JOIN...USING - the join columns,
+                            if NATURAL join, then NULL
+    found_using_fields [out] number of fields from the USING clause that were
+                             found among the common fields
+
+  DESCRIPTION
+    The procedure finds the common columns of two relations (either
+    tables or intermediate join results), and adds an equi-join condition
+    to the ON clause of 'table_ref_2' for each pair of matching columns.
+    If some of table_ref_XXX represents a base table or view, then we
+    create new 'Natural_join_column' instances for each column
+    reference and store them in the 'join_columns' of the table
+    reference.
+
+  IMPLEMENTATION
+    The procedure assumes that store_natural_using_join_columns() was
+    called for the previous level of NATURAL/USING joins.
+
+  RETURN
+    TRUE   error when some common column is non-unique, or out of memory
+    FALSE  OK
+*/
+
+static bool
+mark_common_columns(THD *thd, TABLE_LIST *table_ref_1, TABLE_LIST *table_ref_2,
+                    List<String> *using_fields, uint *found_using_fields)
+{
+  Field_iterator_table_ref it_1, it_2;
+  Natural_join_column *nj_col_1, *nj_col_2;
+  Query_arena *arena, backup;
+  bool result= TRUE;
+  bool first_outer_loop= TRUE;
+  Field *field_1;
+  field_visibility_t field_1_invisible, field_2_invisible;
+  /*
+    Leaf table references to which new natural join columns are added
+    if the leaves are != NULL.
+  */
+  TABLE_LIST *leaf_1= (table_ref_1->nested_join &&
+                       !table_ref_1->is_natural_join) ?
+                      NULL : table_ref_1;
+  TABLE_LIST *leaf_2= (table_ref_2->nested_join &&
+                       !table_ref_2->is_natural_join) ?
+                      NULL : table_ref_2;
+
+  DBUG_ENTER("mark_common_columns");
+  DBUG_PRINT("info", ("operand_1: %s  operand_2: %s",
+                      table_ref_1->alias.str, table_ref_2->alias.str));
+
+  *found_using_fields= 0;
+  arena= thd->activate_stmt_arena_if_needed(&backup);
+
+  for (it_1.set(table_ref_1); !it_1.end_of_fields(); it_1.next())
+  {
+    bool found= FALSE;
+    const LEX_CSTRING *field_name_1;
+    Field *field_2= 0;
+
+    /* true if field_name_1 is a member of using_fields */
+    bool is_using_column_1;
+    if (!(nj_col_1= it_1.get_or_create_column_ref(thd, leaf_1)))
+      goto err;
+
+    field_1= nj_col_1->field();
+    field_1_invisible= field_1 ? field_1->invisible : VISIBLE;
+
+    if (field_1_invisible == INVISIBLE_FULL)
+      continue;
+
+    field_name_1= nj_col_1->name();
+    is_using_column_1= using_fields && 
+      test_if_string_in_list(field_name_1->str, using_fields);
+    DBUG_PRINT ("info", ("field_name_1=%s.%s", 
+                         nj_col_1->safe_table_name(),
+                         field_name_1->str));
+
+    if (field_1_invisible && !is_using_column_1)
+      continue;
+
+    /*
+      Find a field with the same name in table_ref_2.
+
+      Note that for the second loop, it_2.set() will iterate over
+      table_ref_2->join_columns and not generate any new elements or
+      lists.
+    */
+    nj_col_2= NULL;
+    for (it_2.set(table_ref_2); !it_2.end_of_fields(); it_2.next())
+    {
+      Natural_join_column *cur_nj_col_2;
+      const LEX_CSTRING *cur_field_name_2;
+      if (!(cur_nj_col_2= it_2.get_or_create_column_ref(thd, leaf_2)))
+        goto err;
+
+      field_2= cur_nj_col_2->field();
+      field_2_invisible= field_2 ? field_2->invisible : VISIBLE;
+
+      if (field_2_invisible == INVISIBLE_FULL)
+        continue;
+
+      cur_field_name_2= cur_nj_col_2->name();
+      DBUG_PRINT ("info", ("cur_field_name_2=%s.%s", 
+                           cur_nj_col_2->safe_table_name(),
+                           cur_field_name_2->str));
+
+      /*
+        Compare the two columns and check for duplicate common fields.
+        A common field is duplicate either if it was already found in
+        table_ref_2 (then found == TRUE), or if a field in table_ref_2
+        was already matched by some previous field in table_ref_1
+        (then cur_nj_col_2->is_common == TRUE).
+        Note that it is too early to check the columns outside of the
+        USING list for ambiguity because they are not actually "referenced"
+        here. These columns must be checked only on unqualified reference 
+        by name (e.g. in SELECT list).
+      */
+      if (!lex_string_cmp(system_charset_info, field_name_1,
+                          cur_field_name_2))
+      {
+        DBUG_PRINT ("info", ("match c1.is_common=%d", nj_col_1->is_common));
+        if (cur_nj_col_2->is_common || found)
+        {
+          my_error(ER_NON_UNIQ_ERROR, MYF(0), field_name_1->str, thd->where);
+          goto err;
+        }
+        if ((!using_fields && !field_2_invisible) || is_using_column_1)
+        {
+          DBUG_ASSERT(nj_col_2 == NULL);
+          nj_col_2= cur_nj_col_2;
+          found= TRUE;
+        }
+      }
+    }
+    if (first_outer_loop && leaf_2)
+    {
+      /*
+        Make sure that the next inner loop "knows" that all columns
+        are materialized already.
+      */
+      leaf_2->is_join_columns_complete= TRUE;
+      first_outer_loop= FALSE;
+    }
+    if (!found)
+      continue;                                 // No matching field
+
+    /*
+      field_1 and field_2 have the same names. Check if they are in the USING
+      clause (if present), mark them as common fields, and add a new
+      equi-join condition to the ON clause.
+    */
+    if (nj_col_2)
+    {
+      /*
+        Create non-fixed fully qualified field and let fix_fields to
+        resolve it.
+      */
+      Item *item_1=   nj_col_1->create_item(thd);
+      Item *item_2=   nj_col_2->create_item(thd);
+      Item_ident *item_ident_1, *item_ident_2;
+      Item_func_eq *eq_cond;
+
+      if (!item_1 || !item_2)
+        goto err;                               // out of memory
+
+      /*
+        The following assert checks that the two created items are of
+        type Item_ident.
+      */
+      DBUG_ASSERT(!thd->lex->current_select->no_wrap_view_item);
+      /*
+        In the case of no_wrap_view_item == 0, the created items must be
+        of sub-classes of Item_ident.
+      */
+      DBUG_ASSERT(item_1->type() == Item::FIELD_ITEM ||
+                  item_1->type() == Item::REF_ITEM);
+      DBUG_ASSERT(item_2->type() == Item::FIELD_ITEM ||
+                  item_2->type() == Item::REF_ITEM);
+
+      /*
+        We need to cast item_1,2 to Item_ident, because we need to hook name
+        resolution contexts specific to each item.
+      */
+      item_ident_1= (Item_ident*) item_1;
+      item_ident_2= (Item_ident*) item_2;
+      /*
+        Create and hook special name resolution contexts to each item in the
+        new join condition . We need this to both speed-up subsequent name
+        resolution of these items, and to enable proper name resolution of
+        the items during the execute phase of PS.
+      */
+      if (set_new_item_local_context(thd, item_ident_1, nj_col_1->table_ref) ||
+          set_new_item_local_context(thd, item_ident_2, nj_col_2->table_ref))
+        goto err;
+
+      if (!(eq_cond= new (thd->mem_root) Item_func_eq(thd, item_ident_1, item_ident_2)))
+        goto err;                               /* Out of memory. */
+
+      /*
+        Add the new equi-join condition to the ON clause. Notice that
+        fix_fields() is applied to all ON conditions in setup_conds()
+        so we don't do it here.
+      */
+      add_join_on(thd, (table_ref_1->outer_join & JOIN_TYPE_RIGHT ?
+                        table_ref_1 : table_ref_2),
+                  eq_cond);
+
+      nj_col_1->is_common= nj_col_2->is_common= TRUE;
+      DBUG_PRINT ("info", ("%s.%s and %s.%s are common", 
+                           nj_col_1->safe_table_name(),
+                           nj_col_1->name()->str,
+                           nj_col_2->safe_table_name(),
+                           nj_col_2->name()->str));
+
+      if (field_1)
+        update_field_dependencies(thd, field_1, field_1->table);
+      if (field_2)
+        update_field_dependencies(thd, field_2, field_2->table);
+
+      if (using_fields != NULL)
+        ++(*found_using_fields);
+    }
+  }
+  if (leaf_1)
+    leaf_1->is_join_columns_complete= TRUE;
+
+  /*
+    Everything is OK.
+    Notice that at this point there may be some column names in the USING
+    clause that are not among the common columns. This is an SQL error and
+    we check for this error in store_natural_using_join_columns() when
+    (found_using_fields < length(join_using_fields)).
+  */
+  result= FALSE;
+
+err:
+  if (arena)
+    thd->restore_active_arena(arena, &backup);
+  DBUG_RETURN(result);
+}
+
+
+
+/*
+  Materialize and store the row type of NATURAL/USING join.
+
+  SYNOPSIS
+    store_natural_using_join_columns()
+    thd                current thread
+    natural_using_join the table reference of the NATURAL/USING join
+    table_ref_1        the first (left) operand (of a NATURAL/USING join).
+    table_ref_2        the second (right) operand (of a NATURAL/USING join).
+    using_fields       if the join is JOIN...USING - the join columns,
+                       if NATURAL join, then NULL
+    found_using_fields number of fields from the USING clause that were
+                       found among the common fields
+
+  DESCRIPTION
+    Iterate over the columns of both join operands and sort and store
+    all columns into the 'join_columns' list of natural_using_join
+    where the list is formed by three parts:
+      part1: The coalesced columns of table_ref_1 and table_ref_2,
+             sorted according to the column order of the first table.
+      part2: The other columns of the first table, in the order in
+             which they were defined in CREATE TABLE.
+      part3: The other columns of the second table, in the order in
+             which they were defined in CREATE TABLE.
+    Time complexity - O(N1+N2), where Ni = length(table_ref_i).
+
+  IMPLEMENTATION
+    The procedure assumes that mark_common_columns() has been called
+    for the join that is being processed.
+
+  RETURN
+    TRUE    error: Some common column is ambiguous
+    FALSE   OK
+*/
+
+static bool
+store_natural_using_join_columns(THD *thd, TABLE_LIST *natural_using_join,
+                                 TABLE_LIST *table_ref_1,
+                                 TABLE_LIST *table_ref_2,
+                                 List<String> *using_fields,
+                                 uint found_using_fields)
+{
+  Field_iterator_table_ref it_1, it_2;
+  Natural_join_column *nj_col_1, *nj_col_2;
+  Query_arena *arena, backup;
+  bool result= TRUE;
+  List<Natural_join_column> *non_join_columns;
+  List<Natural_join_column> *join_columns;
+  DBUG_ENTER("store_natural_using_join_columns");
+
+  DBUG_ASSERT(!natural_using_join->join_columns);
+
+  arena= thd->activate_stmt_arena_if_needed(&backup);
+
+  if (!(non_join_columns= new List<Natural_join_column>) ||
+      !(join_columns= new List<Natural_join_column>))
+    goto err;
+
+  /* Append the columns of the first join operand. */
+  for (it_1.set(table_ref_1); !it_1.end_of_fields(); it_1.next())
+  {
+    nj_col_1= it_1.get_natural_column_ref();
+    if (nj_col_1->is_common)
+    {
+      join_columns->push_back(nj_col_1, thd->mem_root);
+      /* Reset the common columns for the next call to mark_common_columns. */
+      nj_col_1->is_common= FALSE;
+    }
+    else
+      non_join_columns->push_back(nj_col_1, thd->mem_root);
+  }
+
+  /*
+    Check that all columns in the USING clause are among the common
+    columns. If this is not the case, report the first one that was
+    not found in an error.
+  */
+  if (using_fields && found_using_fields < using_fields->elements)
+  {
+    String *using_field_name;
+    List_iterator_fast<String> using_fields_it(*using_fields);
+    while ((using_field_name= using_fields_it++))
+    {
+      const char *using_field_name_ptr= using_field_name->c_ptr();
+      List_iterator_fast<Natural_join_column>
+        it(*join_columns);
+      Natural_join_column *common_field;
+
+      for (;;)
+      {
+        /* If reached the end of fields, and none was found, report error. */
+        if (!(common_field= it++))
+        {
+          my_error(ER_BAD_FIELD_ERROR, MYF(0), using_field_name_ptr,
+                   current_thd->where);
+          goto err;
+        }
+        if (!my_strcasecmp(system_charset_info,
+                           common_field->name()->str, using_field_name_ptr))
+          break;                                // Found match
+      }
+    }
+  }
+
+  /* Append the non-equi-join columns of the second join operand. */
+  for (it_2.set(table_ref_2); !it_2.end_of_fields(); it_2.next())
+  {
+    nj_col_2= it_2.get_natural_column_ref();
+    if (!nj_col_2->is_common)
+      non_join_columns->push_back(nj_col_2, thd->mem_root);
+    else
+    {
+      /* Reset the common columns for the next call to mark_common_columns. */
+      nj_col_2->is_common= FALSE;
+    }
+  }
+
+  if (non_join_columns->elements > 0)
+    join_columns->append(non_join_columns);
+  natural_using_join->join_columns= join_columns;
+  natural_using_join->is_join_columns_complete= TRUE;
+
+  result= FALSE;
+
+  if (arena)
+    thd->restore_active_arena(arena, &backup);
+  DBUG_RETURN(result);
+
+err:
+  /*
+     Actually we failed to build join columns list, so we have to
+     clear it to avoid problems with half-build join on next run.
+     The list was created in mark_common_columns().
+   */
+  table_ref_1->remove_join_columns();
+  table_ref_2->remove_join_columns();
+
+  if (arena)
+    thd->restore_active_arena(arena, &backup);
+  DBUG_RETURN(TRUE);
+}
+
+
+/*
+  Precompute and store the row types of the top-most NATURAL/USING joins.
+
+  SYNOPSIS
+    store_top_level_join_columns()
+    thd            current thread
+    table_ref      nested join or table in a FROM clause
+    left_neighbor  neighbor table reference to the left of table_ref at the
+                   same level in the join tree
+    right_neighbor neighbor table reference to the right of table_ref at the
+                   same level in the join tree
+
+  DESCRIPTION
+    The procedure performs a post-order traversal of a nested join tree
+    and materializes the row types of NATURAL/USING joins in a
+    bottom-up manner until it reaches the TABLE_LIST elements that
+    represent the top-most NATURAL/USING joins. The procedure should be
+    applied to each element of SELECT_LEX::top_join_list (i.e. to each
+    top-level element of the FROM clause).
+
+  IMPLEMENTATION
+    Notice that the table references in the list nested_join->join_list
+    are in reverse order, thus when we iterate over it, we are moving
+    from the right to the left in the FROM clause.
+
+  RETURN
+    TRUE   Error
+    FALSE  OK
+*/
+
+static bool
+store_top_level_join_columns(THD *thd, TABLE_LIST *table_ref,
+                             TABLE_LIST *left_neighbor,
+                             TABLE_LIST *right_neighbor)
+{
+  Query_arena *arena, backup;
+  bool result= TRUE;
+
+  DBUG_ENTER("store_top_level_join_columns");
+
+  arena= thd->activate_stmt_arena_if_needed(&backup);
+
+  /* Call the procedure recursively for each nested table reference. */
+  if (table_ref->nested_join)
+  {
+    List_iterator_fast<TABLE_LIST> nested_it(table_ref->nested_join->join_list);
+    TABLE_LIST *same_level_left_neighbor= nested_it++;
+    TABLE_LIST *same_level_right_neighbor= NULL;
+    /* Left/right-most neighbors, possibly at higher levels in the join tree. */
+    TABLE_LIST *real_left_neighbor, *real_right_neighbor;
+
+    while (same_level_left_neighbor)
+    {
+      TABLE_LIST *cur_table_ref= same_level_left_neighbor;
+      same_level_left_neighbor= nested_it++;
+      /*
+        The order of RIGHT JOIN operands is reversed in 'join list' to
+        transform it into a LEFT JOIN. However, in this procedure we need
+        the join operands in their lexical order, so below we reverse the
+        join operands. Notice that this happens only in the first loop,
+        and not in the second one, as in the second loop
+        same_level_left_neighbor == NULL.
+        This is the correct behavior, because the second loop sets
+        cur_table_ref reference correctly after the join operands are
+        swapped in the first loop.
+      */
+      if (same_level_left_neighbor &&
+          cur_table_ref->outer_join & JOIN_TYPE_RIGHT)
+      {
+        /* This can happen only for JOIN ... ON. */
+        DBUG_ASSERT(table_ref->nested_join->join_list.elements == 2);
+        swap_variables(TABLE_LIST*, same_level_left_neighbor, cur_table_ref);
+      }
+
+      /*
+        Pick the parent's left and right neighbors if there are no immediate
+        neighbors at the same level.
+      */
+      real_left_neighbor=  (same_level_left_neighbor) ?
+                           same_level_left_neighbor : left_neighbor;
+      real_right_neighbor= (same_level_right_neighbor) ?
+                           same_level_right_neighbor : right_neighbor;
+
+      if (cur_table_ref->nested_join &&
+          store_top_level_join_columns(thd, cur_table_ref,
+                                       real_left_neighbor, real_right_neighbor))
+        goto err;
+      same_level_right_neighbor= cur_table_ref;
+    }
+  }
+
+  /*
+    If this is a NATURAL/USING join, materialize its result columns and
+    convert to a JOIN ... ON.
+  */
+  if (table_ref->is_natural_join)
+  {
+    DBUG_ASSERT(table_ref->nested_join &&
+                table_ref->nested_join->join_list.elements == 2);
+    List_iterator_fast<TABLE_LIST> operand_it(table_ref->nested_join->join_list);
+    /*
+      Notice that the order of join operands depends on whether table_ref
+      represents a LEFT or a RIGHT join. In a RIGHT join, the operands are
+      in inverted order.
+     */
+    TABLE_LIST *table_ref_2= operand_it++; /* Second NATURAL join operand.*/
+    TABLE_LIST *table_ref_1= operand_it++; /* First NATURAL join operand. */
+    List<String> *using_fields= table_ref->join_using_fields;
+    uint found_using_fields;
+
+    /*
+      The two join operands were interchanged in the parser, change the order
+      back for 'mark_common_columns'.
+    */
+    if (table_ref_2->outer_join & JOIN_TYPE_RIGHT)
+      swap_variables(TABLE_LIST*, table_ref_1, table_ref_2);
+    if (mark_common_columns(thd, table_ref_1, table_ref_2,
+                            using_fields, &found_using_fields))
+      goto err;
+
+    /*
+      Swap the join operands back, so that we pick the columns of the second
+      one as the coalesced columns. In this way the coalesced columns are the
+      same as of an equivalent LEFT JOIN.
+    */
+    if (table_ref_1->outer_join & JOIN_TYPE_RIGHT)
+      swap_variables(TABLE_LIST*, table_ref_1, table_ref_2);
+    if (store_natural_using_join_columns(thd, table_ref, table_ref_1,
+                                         table_ref_2, using_fields,
+                                         found_using_fields))
+      goto err;
+
+    /*
+      Change NATURAL JOIN to JOIN ... ON. We do this for both operands
+      because either one of them or the other is the one with the
+      natural join flag because RIGHT joins are transformed into LEFT,
+      and the two tables may be reordered.
+    */
+    table_ref_1->natural_join= table_ref_2->natural_join= NULL;
+
+    /* Add a TRUE condition to outer joins that have no common columns. */
+    if (table_ref_2->outer_join &&
+        !table_ref_1->on_expr && !table_ref_2->on_expr)
+      table_ref_2->on_expr= new (thd->mem_root) Item_int(thd, (longlong) 1, 1); // Always true.
+
+    /* Change this table reference to become a leaf for name resolution. */
+    if (left_neighbor)
+    {
+      TABLE_LIST *last_leaf_on_the_left;
+      last_leaf_on_the_left= left_neighbor->last_leaf_for_name_resolution();
+      last_leaf_on_the_left->next_name_resolution_table= table_ref;
+    }
+    if (right_neighbor)
+    {
+      TABLE_LIST *first_leaf_on_the_right;
+      first_leaf_on_the_right= right_neighbor->first_leaf_for_name_resolution();
+      table_ref->next_name_resolution_table= first_leaf_on_the_right;
+    }
+    else
+      table_ref->next_name_resolution_table= NULL;
+  }
+  result= FALSE; /* All is OK. */
+
+err:
+  if (arena)
+    thd->restore_active_arena(arena, &backup);
+  DBUG_RETURN(result);
+}
+
+
+/*
+  Compute and store the row types of the top-most NATURAL/USING joins
+  in a FROM clause.
+
+  SYNOPSIS
+    setup_natural_join_row_types()
+    thd          current thread
+    from_clause  list of top-level table references in a FROM clause
+
+  DESCRIPTION
+    Apply the procedure 'store_top_level_join_columns' to each of the
+    top-level table referencs of the FROM clause. Adjust the list of tables
+    for name resolution - context->first_name_resolution_table to the
+    top-most, lef-most NATURAL/USING join.
+
+  IMPLEMENTATION
+    Notice that the table references in 'from_clause' are in reverse
+    order, thus when we iterate over it, we are moving from the right
+    to the left in the FROM clause.
+
+  NOTES
+    We can't run this many times as the first_name_resolution_table would
+    be different for subsequent runs when sub queries has been optimized
+    away.
+
+  RETURN
+    TRUE   Error
+    FALSE  OK
+*/
+
+static bool setup_natural_join_row_types(THD *thd,
+                                         List<TABLE_LIST> *from_clause,
+                                         Name_resolution_context *context)
+{
+  DBUG_ENTER("setup_natural_join_row_types");
+  thd->where= "from clause";
+  if (from_clause->elements == 0)
+    DBUG_RETURN(false); /* We come here in the case of UNIONs. */
+
+  /* 
+     Do not redo work if already done:
+     1) for stored procedures,
+     2) for multitable update after lock failure and table reopening.
+  */
+  if (!context->select_lex->first_natural_join_processing)
+  {
+    context->first_name_resolution_table= context->natural_join_first_table;
+    DBUG_PRINT("info", ("using cached setup_natural_join_row_types"));
+    DBUG_RETURN(false);
+  }
+
+  List_iterator_fast<TABLE_LIST> table_ref_it(*from_clause);
+  TABLE_LIST *table_ref; /* Current table reference. */
+  /* Table reference to the left of the current. */
+  TABLE_LIST *left_neighbor;
+  /* Table reference to the right of the current. */
+  TABLE_LIST *right_neighbor= NULL;
+
+  /* Note that tables in the list are in reversed order */
+  for (left_neighbor= table_ref_it++; left_neighbor ; )
+  {
+    table_ref= left_neighbor;
+    do
+    {
+      left_neighbor= table_ref_it++;
+    }
+    while (left_neighbor && left_neighbor->sj_subq_pred);
+
+    if (store_top_level_join_columns(thd, table_ref,
+                                     left_neighbor, right_neighbor))
+      DBUG_RETURN(true);
+    if (left_neighbor)
+    {
+      TABLE_LIST *first_leaf_on_the_right;
+      first_leaf_on_the_right= table_ref->first_leaf_for_name_resolution();
+      left_neighbor->next_name_resolution_table= first_leaf_on_the_right;
+    }
+    right_neighbor= table_ref;
+  }
+
+  /*
+    Store the top-most, left-most NATURAL/USING join, so that we start
+    the search from that one instead of context->table_list. At this point
+    right_neighbor points to the left-most top-level table reference in the
+    FROM clause.
+  */
+  DBUG_ASSERT(right_neighbor);
+  context->first_name_resolution_table=
+    right_neighbor->first_leaf_for_name_resolution();
+  /*
+    This is only to ensure that first_name_resolution_table doesn't
+    change on re-execution
+  */
+  context->natural_join_first_table= context->first_name_resolution_table;
+  context->select_lex->first_natural_join_processing= false;
+  DBUG_RETURN (false);
+}
+
+
+/****************************************************************************
+** Expand all '*' in given fields
+****************************************************************************/
+
+int setup_wild(THD *thd, TABLE_LIST *tables, List<Item> &fields,
+	       List<Item> *sum_func_list, SELECT_LEX *select_lex, bool returning_field)
+{
+  Item *item;
+  List_iterator<Item> it(fields);
+  Query_arena *arena, backup;
+  DBUG_ENTER("setup_wild");
+
+  if (!select_lex->with_wild)
+    DBUG_RETURN(0);
+
+  /*
+    Don't use arena if we are not in prepared statements or stored procedures
+    For PS/SP we have to use arena to remember the changes
+  */
+  arena= thd->activate_stmt_arena_if_needed(&backup);
+
+  thd->lex->current_select->cur_pos_in_select_list= 0;
+  while (select_lex->with_wild && (item= it++))
+  {
+    if (item->type() == Item::FIELD_ITEM &&
+        ((Item_field*) item)->field_name.str == star_clex_str.str &&
+	!((Item_field*) item)->field)
+    {
+      uint elem= fields.elements;
+      bool any_privileges= ((Item_field *) item)->any_privileges;
+      Item_subselect *subsel= thd->lex->current_select->master_unit()->item;
+      if (subsel &&
+          subsel->substype() == Item_subselect::EXISTS_SUBS)
+      {
+        /*
+          It is EXISTS(SELECT * ...) and we can replace * by any constant.
+
+          Item_int do not need fix_fields() because it is basic constant.
+        */
+        it.replace(new (thd->mem_root) Item_int(thd, "Not_used", (longlong) 1,
+                                MY_INT64_NUM_DECIMAL_DIGITS));
+      }
+      else if (insert_fields(thd, ((Item_field*) item)->context,
+                             ((Item_field*) item)->db_name.str,
+                             ((Item_field*) item)->table_name.str, &it,
+                             any_privileges, &select_lex->hidden_bit_fields, returning_field))
+      {
+	if (arena)
+	  thd->restore_active_arena(arena, &backup);
+	DBUG_RETURN(-1);
+      }
+      if (sum_func_list)
+      {
+	/*
+	  sum_func_list is a list that has the fields list as a tail.
+	  Because of this we have to update the element count also for this
+	  list after expanding the '*' entry.
+	*/
+	sum_func_list->elements+= fields.elements - elem;
+      }
+      select_lex->with_wild--;
+    }
+    else
+      thd->lex->current_select->cur_pos_in_select_list++;
+  }
+  DBUG_ASSERT(!select_lex->with_wild);
+  thd->lex->current_select->cur_pos_in_select_list= UNDEF_POS;
+  if (arena)
+    thd->restore_active_arena(arena, &backup);
+  DBUG_RETURN(0);
+}
+
+/****************************************************************************
+** Check that all given fields exists and fill struct with current data
+****************************************************************************/
+
+bool setup_fields(THD *thd, Ref_ptr_array ref_pointer_array,
+                  List<Item> &fields, enum_column_usage column_usage,
+                  List<Item> *sum_func_list, List<Item> *pre_fix,
+                  bool allow_sum_func)
+{
+  Item *item;
+  enum_column_usage saved_column_usage= thd->column_usage;
+  nesting_map save_allow_sum_func= thd->lex->allow_sum_func;
+  List_iterator<Item> it(fields);
+  bool save_is_item_list_lookup;
+  bool make_pre_fix= (pre_fix && (pre_fix->elements == 0));
+  DBUG_ENTER("setup_fields");
+  DBUG_PRINT("enter", ("ref_pointer_array: %p", ref_pointer_array.array()));
+
+  thd->column_usage= column_usage;
+  DBUG_PRINT("info", ("thd->column_usage: %d", thd->column_usage));
+  if (allow_sum_func)
+    thd->lex->allow_sum_func.set_bit(thd->lex->current_select->nest_level);
+  thd->where= THD::DEFAULT_WHERE;
+  save_is_item_list_lookup= thd->lex->current_select->is_item_list_lookup;
+  thd->lex->current_select->is_item_list_lookup= 0;
+
+  /*
+    To prevent fail on forward lookup we fill it with zeroes,
+    then if we got pointer on zero after find_item_in_list we will know
+    that it is forward lookup.
+
+    There is other way to solve problem: fill array with pointers to list,
+    but it will be slower.
+
+    TODO: remove it when (if) we made one list for allfields and
+    ref_pointer_array
+  */
+  if (!ref_pointer_array.is_null())
+  {
+    DBUG_ASSERT(ref_pointer_array.size() >= fields.elements);
+    memset(ref_pointer_array.array(), 0, sizeof(Item *) * fields.elements);
+  }
+
+  /*
+    We call set_entry() there (before fix_fields() of the whole list of field
+    items) because:
+    1) the list of field items has same order as in the query, and the
+       Item_func_get_user_var item may go before the Item_func_set_user_var:
+          SELECT @a, @a := 10 FROM t;
+    2) The entry->update_query_id value controls constantness of
+       Item_func_get_user_var items, so in presence of Item_func_set_user_var
+       items we have to refresh their entries before fixing of
+       Item_func_get_user_var items.
+  */
+  List_iterator<Item_func_set_user_var> li(thd->lex->set_var_list);
+  Item_func_set_user_var *var;
+  while ((var= li++))
+    var->set_entry(thd, FALSE);
+
+  Ref_ptr_array ref= ref_pointer_array;
+  thd->lex->current_select->cur_pos_in_select_list= 0;
+  while ((item= it++))
+  {
+    if (make_pre_fix)
+      pre_fix->push_back(item, thd->stmt_arena->mem_root);
+
+    if (item->fix_fields_if_needed_for_scalar(thd, it.ref()))
+    {
+      thd->lex->current_select->is_item_list_lookup= save_is_item_list_lookup;
+      thd->lex->allow_sum_func= save_allow_sum_func;
+      thd->column_usage= saved_column_usage;
+      DBUG_PRINT("info", ("thd->column_usage: %d", thd->column_usage));
+      DBUG_RETURN(TRUE); /* purecov: inspected */
+    }
+    item= *(it.ref()); // Item might have changed in fix_fields()
+    if (!ref.is_null())
+    {
+      ref[0]= item;
+      ref.pop_front();
+    }
+    /*
+      split_sum_func() must be called for Window Function items, see
+      Item_window_func::split_sum_func.
+    */
+    if (sum_func_list &&
+         ((item->with_sum_func() && item->type() != Item::SUM_FUNC_ITEM) ||
+          item->with_window_func))
+    {
+      item->split_sum_func(thd, ref_pointer_array, *sum_func_list,
+                           SPLIT_SUM_SELECT);
+    }
+    thd->lex->current_select->select_list_tables|= item->used_tables();
+    thd->lex->used_tables|= item->used_tables();
+    thd->lex->current_select->cur_pos_in_select_list++;
+  }
+  thd->lex->current_select->is_item_list_lookup= save_is_item_list_lookup;
+  thd->lex->current_select->cur_pos_in_select_list= UNDEF_POS;
+
+  thd->lex->allow_sum_func= save_allow_sum_func;
+  thd->column_usage= saved_column_usage;
+  DBUG_PRINT("info", ("thd->column_usage: %d", thd->column_usage));
+  DBUG_RETURN(MY_TEST(thd->is_error()));
+}
+
+
+/*
+  Perform checks like all given fields exists, if exists fill struct with
+  current data and expand all '*' in given fields for LEX::returning.
+
+  SYNOPSIS
+     thd                 Thread handler
+     table_list          Global/local table list
+*/
+
+int setup_returning_fields(THD* thd, TABLE_LIST* table_list)
+{
+  if (!thd->lex->has_returning())
+    return 0;
+  return setup_wild(thd, table_list, thd->lex->returning()->item_list, NULL,
+                    thd->lex->returning(), true)
+      || setup_fields(thd, Ref_ptr_array(), thd->lex->returning()->item_list,
+                      MARK_COLUMNS_READ, NULL, NULL, false);
+}
+
+
+/*
+  make list of leaves of join table tree
+
+  SYNOPSIS
+    make_leaves_list()
+    list    pointer to pointer on list first element
+    tables  table list
+    full_table_list whether to include tables from mergeable derived table/view.
+                    we need them for checks for INSERT/UPDATE statements only.
+
+  RETURN pointer on pointer to next_leaf of last element
+*/
+
+void make_leaves_list(THD *thd, List<TABLE_LIST> &list, TABLE_LIST *tables,
+                      bool full_table_list, TABLE_LIST *boundary)
+ 
+{
+  for (TABLE_LIST *table= tables; table; table= table->next_local)
+  {
+    if (table == boundary)
+      full_table_list= !full_table_list;
+    if (full_table_list && table->is_merged_derived())
+    {
+      SELECT_LEX *select_lex= table->get_single_select();
+      /*
+        It's safe to use select_lex->leaf_tables because all derived
+        tables/views were already prepared and has their leaf_tables
+        set properly.
+      */
+      make_leaves_list(thd, list, select_lex->get_table_list(),
+      full_table_list, boundary);
+    }
+    else
+    {
+      list.push_back(table, thd->mem_root);
+    }
+  }
+}
+
+/*
+  prepare tables
+
+  SYNOPSIS
+    setup_tables()
+    thd		  Thread handler
+    context       name resolution contest to setup table list there
+    from_clause   Top-level list of table references in the FROM clause
+    tables	  Table list (select_lex->table_list)
+    leaves        List of join table leaves list (select_lex->leaf_tables)
+    refresh       It is only refresh for subquery
+    select_insert It is SELECT ... INSERT command
+    full_table_list a parameter to pass to the make_leaves_list function
+
+  NOTE
+    Check also that the 'used keys' and 'ignored keys' exists and set up the
+    table structure accordingly.
+    Create a list of leaf tables. For queries with NATURAL/USING JOINs,
+    compute the row types of the top most natural/using join table references
+    and link these into a list of table references for name resolution.
+
+    This has to be called for all tables that are used by items, as otherwise
+    table->map is not set and all Item_field will be regarded as const items.
+
+  RETURN
+    FALSE ok;  In this case *map will includes the chosen index
+    TRUE  error
+*/
+
+bool setup_tables(THD *thd, Name_resolution_context *context,
+                  List<TABLE_LIST> *from_clause, TABLE_LIST *tables,
+                  List<TABLE_LIST> &leaves, bool select_insert,
+                  bool full_table_list)
+{
+  uint tablenr= 0;
+  List_iterator<TABLE_LIST> ti(leaves);
+  TABLE_LIST *table_list;
+
+  DBUG_ENTER("setup_tables");
+
+  DBUG_ASSERT ((select_insert && !tables->next_name_resolution_table) || !tables || 
+               (context->table_list && context->first_name_resolution_table));
+  /*
+    this is used for INSERT ... SELECT.
+    For select we setup tables except first (and its underlying tables)
+  */
+  TABLE_LIST *first_select_table= (select_insert ?
+                                   tables->next_local:
+                                   0);
+  SELECT_LEX *select_lex= select_insert ? thd->lex->first_select_lex() :
+                                          thd->lex->current_select;
+  if (select_lex->first_cond_optimization)
+  {
+    leaves.empty();
+    if (select_lex->prep_leaf_list_state != SELECT_LEX::SAVED)
+    {
+      make_leaves_list(thd, leaves, tables, full_table_list, first_select_table);
+      select_lex->prep_leaf_list_state= SELECT_LEX::READY;
+      select_lex->leaf_tables_exec.empty();
+    }
+    else
+    {
+      List_iterator_fast <TABLE_LIST> ti(select_lex->leaf_tables_prep);
+      while ((table_list= ti++))
+        leaves.push_back(table_list, thd->mem_root);
+    }
+      
+    while ((table_list= ti++))
+    {
+      TABLE *table= table_list->table;
+      if (table)
+        table->pos_in_table_list= table_list;
+      if (first_select_table &&
+          table_list->top_table() == first_select_table)
+      {
+        /* new counting for SELECT of INSERT ... SELECT command */
+        first_select_table= 0;
+        thd->lex->first_select_lex()->insert_tables= tablenr;
+        tablenr= 0;
+      }
+      if(table_list->jtbm_subselect)
+      {
+        table_list->jtbm_table_no= tablenr;
+      }
+      else if (table)
+      {
+        table->pos_in_table_list= table_list;
+        setup_table_map(table, table_list, tablenr);
+
+        if (table_list->process_index_hints(table))
+          DBUG_RETURN(1);
+      }
+      tablenr++;
+      /*
+        We test the max tables here as we setup_table_map() should not be called
+        with tablenr >= 64
+      */
+      if (tablenr > MAX_TABLES)
+      {
+        my_error(ER_TOO_MANY_TABLES,MYF(0), static_cast<int>(MAX_TABLES));
+        DBUG_RETURN(1);
+      }
+    }
+  }
+  else
+  { 
+    List_iterator_fast <TABLE_LIST> ti(select_lex->leaf_tables_exec);
+    select_lex->leaf_tables.empty();
+    while ((table_list= ti++))
+    {
+      if(table_list->jtbm_subselect)
+      {
+        table_list->jtbm_table_no= table_list->tablenr_exec;
+      }
+      else
+      {
+        table_list->table->tablenr= table_list->tablenr_exec;
+        table_list->table->map= table_list->map_exec;
+        table_list->table->maybe_null= table_list->maybe_null_exec;
+        table_list->table->pos_in_table_list= table_list;
+        if (table_list->process_index_hints(table_list->table))
+          DBUG_RETURN(1);
+      }
+      select_lex->leaf_tables.push_back(table_list);
+    }
+  }    
+
+  for (table_list= tables;
+       table_list;
+       table_list= table_list->next_local)
+  {
+    if (table_list->merge_underlying_list)
+    {
+      DBUG_ASSERT(table_list->is_merged_derived());
+      Query_arena *arena, backup;
+      arena= thd->activate_stmt_arena_if_needed(&backup);
+      bool res;
+      res= table_list->setup_underlying(thd);
+      if (arena)
+        thd->restore_active_arena(arena, &backup);
+      if (res)
+        DBUG_RETURN(1);
+    }
+
+    if (table_list->jtbm_subselect)
+    {
+      Item *item= table_list->jtbm_subselect->optimizer;
+      if (!table_list->jtbm_subselect->optimizer->fixed &&
+          table_list->jtbm_subselect->optimizer->fix_fields(thd, &item))
+      {
+        my_error(ER_TOO_MANY_TABLES,MYF(0), static_cast<int>(MAX_TABLES)); /* psergey-todo: WHY ER_TOO_MANY_TABLES ???*/
+        DBUG_RETURN(1);
+      }
+      DBUG_ASSERT(item == table_list->jtbm_subselect->optimizer);
+    }
+  }
+
+  /* Precompute and store the row types of NATURAL/USING joins. */
+  if (setup_natural_join_row_types(thd, from_clause, context))
+    DBUG_RETURN(1);
+
+  DBUG_RETURN(0);
+}
+
+
+/*
+  prepare tables and check access for the view tables
+
+  SYNOPSIS
+    setup_tables_and_check_access()
+    thd		  Thread handler
+    context       name resolution contest to setup table list there
+    from_clause   Top-level list of table references in the FROM clause
+    tables	  Table list (select_lex->table_list)
+    conds	  Condition of current SELECT (can be changed by VIEW)
+    leaves        List of join table leaves list (select_lex->leaf_tables)
+    refresh       It is onle refresh for subquery
+    select_insert It is SELECT ... INSERT command
+    want_access   what access is needed
+    full_table_list a parameter to pass to the make_leaves_list function
+
+  NOTE
+    a wrapper for check_tables that will also check the resulting
+    table leaves list for access to all the tables that belong to a view
+
+  RETURN
+    FALSE ok;  In this case *map will include the chosen index
+    TRUE  error
+*/
+bool setup_tables_and_check_access(THD *thd, Name_resolution_context *context,
+                                   List<TABLE_LIST> *from_clause,
+                                   TABLE_LIST *tables,
+                                   List<TABLE_LIST> &leaves,
+                                   bool select_insert,
+                                   privilege_t want_access_first,
+                                   privilege_t want_access,
+                                   bool full_table_list)
+{
+  DBUG_ENTER("setup_tables_and_check_access");
+
+  if (setup_tables(thd, context, from_clause, tables,
+                   leaves, select_insert, full_table_list))
+    DBUG_RETURN(TRUE);
+
+  List_iterator<TABLE_LIST> ti(leaves);
+  TABLE_LIST *table_list;
+  privilege_t access= want_access_first;
+  while ((table_list= ti++))
+  {
+    if (table_list->belong_to_view && !table_list->view && 
+        check_single_table_access(thd, access, table_list, FALSE))
+    {
+      tables->hide_view_error(thd);
+      DBUG_RETURN(TRUE);
+    }
+    access= want_access;
+  }
+  DBUG_RETURN(FALSE);
+}
+
+
+/*
+   Create a key_map from a list of index names
+
+   SYNOPSIS
+     get_key_map_from_key_list()
+     map		key_map to fill in
+     table		Table
+     index_list		List of index names
+
+   RETURN
+     0	ok;  In this case *map will includes the choosed index
+     1	error
+*/
+
+bool get_key_map_from_key_list(key_map *map, TABLE *table,
+                               List<String> *index_list)
+{
+  List_iterator_fast<String> it(*index_list);
+  String *name;
+  uint pos;
+
+  map->clear_all();
+  while ((name=it++))
+  {
+    if (table->s->keynames.type_names == 0 ||
+        (pos= find_type(&table->s->keynames, name->ptr(),
+                        name->length(), 1)) <=
+        0)
+    {
+      my_error(ER_KEY_DOES_NOT_EXISTS, MYF(0), name->c_ptr(),
+	       table->pos_in_table_list->alias.str);
+      map->set_all();
+      return 1;
+    }
+    map->set_bit(pos-1);
+  }
+  return 0;
+}
+
+
+/*
+  Drops in all fields instead of current '*' field
+
+  SYNOPSIS
+    insert_fields()
+    thd			Thread handler
+    context             Context for name resolution
+    db_name		Database name in case of 'database_name.table_name.*'
+    table_name		Table name in case of 'table_name.*'
+    it			Pointer to '*'
+    any_privileges	0 If we should ensure that we have SELECT privileges
+		          for all columns
+                        1 If any privilege is ok
+  RETURN
+    0	ok     'it' is updated to point at last inserted
+    1	error.  Error message is generated but not sent to client
+*/
+
+bool
+insert_fields(THD *thd, Name_resolution_context *context, const char *db_name,
+	      const char *table_name, List_iterator<Item> *it,
+              bool any_privileges, uint *hidden_bit_fields, bool returning_field)
+{
+  Field_iterator_table_ref field_iterator;
+  bool found;
+  char name_buff[SAFE_NAME_LEN+1];
+  DBUG_ENTER("insert_fields");
+  DBUG_PRINT("arena", ("stmt arena: %p",thd->stmt_arena));
+
+  if (db_name && lower_case_table_names)
+  {
+    /*
+      convert database to lower case for comparison
+      We can't do this in Item_field as this would change the
+      'name' of the item which may be used in the select list
+    */
+    strmake_buf(name_buff, db_name);
+    my_casedn_str(files_charset_info, name_buff);
+    db_name= name_buff;
+  }
+
+  found= FALSE;
+
+  /*
+    If table names are qualified, then loop over all tables used in the query,
+    else treat natural joins as leaves and do not iterate over their underlying
+    tables.
+  */
+  TABLE_LIST *first= context->first_name_resolution_table;
+  TABLE_LIST *TABLE_LIST::* next= &TABLE_LIST::next_name_resolution_table;
+  if (table_name && !returning_field)
+  {
+    first= context->table_list;
+    next= &TABLE_LIST::next_local;
+  }
+  for (TABLE_LIST *tables= first; tables; tables= tables->*next)
+  {
+    Field *field;
+    TABLE *table= tables->table;
+
+    DBUG_ASSERT(tables->is_leaf_for_name_resolution());
+
+    if ((table_name && my_strcasecmp(table_alias_charset, table_name,
+                                     tables->alias.str)) ||
+        (db_name && strcmp(tables->db.str, db_name)))
+      continue;
+
+#ifndef NO_EMBEDDED_ACCESS_CHECKS
+    /* 
+       Ensure that we have access rights to all fields to be inserted
+       the table 'tables'. Under some circumstances, this check may be skipped.
+
+       The check is skipped in the following cases:
+
+       - any_privileges is true
+
+       - the table is a derived table
+
+       - the table is a view with SELECT privilege
+
+       - the table is a base table with SELECT privilege
+    */
+    if (!any_privileges &&
+        !tables->is_derived() &&
+        !(tables->is_view() && (tables->grant.privilege & SELECT_ACL)) &&
+        !(table && (table->grant.privilege & SELECT_ACL)))
+    {
+      field_iterator.set(tables);
+      if (check_grant_all_columns(thd, SELECT_ACL, &field_iterator))
+        DBUG_RETURN(TRUE);
+    }
+#endif
+
+    /*
+      Update the tables used in the query based on the referenced fields. For
+      views and natural joins this update is performed inside the loop below.
+    */
+    if (table)
+    {
+      thd->lex->used_tables|= table->map;
+      thd->lex->current_select->select_list_tables|= table->map;
+    }
+
+    /*
+      Initialize a generic field iterator for the current table reference.
+      Notice that it is guaranteed that this iterator will iterate over the
+      fields of a single table reference, because 'tables' is a leaf (for
+      name resolution purposes).
+    */
+    field_iterator.set(tables);
+
+    for (; !field_iterator.end_of_fields(); field_iterator.next())
+    {
+      /*
+        field() is always NULL for views (see, e.g. Field_iterator_view or
+        Field_iterator_natural_join).
+        But view fields can never be invisible.
+      */
+      if ((field= field_iterator.field()) && field->invisible != VISIBLE)
+        continue;
+
+      Item *item;
+
+      if (!(item= field_iterator.create_item(thd)))
+        DBUG_RETURN(TRUE);
+
+      /* cache the table for the Item_fields inserted by expanding stars */
+      if (item->type() == Item::FIELD_ITEM && tables->cacheable_table)
+        ((Item_field *)item)->cached_table= tables;
+
+      if (!found)
+      {
+        found= TRUE;
+        it->replace(item); /* Replace '*' with the first found item. */
+      }
+      else
+        it->after(item);   /* Add 'item' to the SELECT list. */
+
+      if (item->type() == Item::FIELD_ITEM && item->field_type() == MYSQL_TYPE_BIT)
+        (*hidden_bit_fields)++;
+
+#ifndef NO_EMBEDDED_ACCESS_CHECKS
+      /*
+        Set privilege information for the fields of newly created views.
+        We have that (any_priviliges == TRUE) if and only if we are creating
+        a view. In the time of view creation we can't use the MERGE algorithm,
+        therefore if 'tables' is itself a view, it is represented by a
+        temporary table. Thus in this case we can be sure that 'item' is an
+        Item_field.
+      */
+      if (any_privileges && !tables->is_with_table() && !tables->is_derived())
+      {
+        DBUG_ASSERT((tables->field_translation == NULL && table) ||
+                    tables->is_natural_join);
+        DBUG_ASSERT(item->type() == Item::FIELD_ITEM);
+        Item_field *fld= (Item_field*) item;
+        const char *field_table_name= field_iterator.get_table_name();
+
+        if (!tables->schema_table && 
+            !(fld->have_privileges=
+              (get_column_grant(thd, field_iterator.grant(),
+                                field_iterator.get_db_name(),
+                                field_table_name, fld->field_name.str) &
+               VIEW_ANY_ACL)))
+        {
+          my_error(ER_TABLEACCESS_DENIED_ERROR, MYF(0), "ANY",
+                   thd->security_ctx->priv_user,
+                   thd->security_ctx->host_or_ip,
+                   field_table_name);
+          DBUG_RETURN(TRUE);
+        }
+      }
+#endif
+
+      if ((field= field_iterator.field()))
+      {
+        field->table->mark_column_with_deps(field);
+        if (table)
+          table->covering_keys.intersect(field->part_of_key);
+        if (tables->is_natural_join)
+        {
+          TABLE *field_table;
+          /*
+            In this case we are sure that the column ref will not be created
+            because it was already created and stored with the natural join.
+          */
+          Natural_join_column *nj_col;
+          if (!(nj_col= field_iterator.get_natural_column_ref()))
+            DBUG_RETURN(TRUE);
+          DBUG_ASSERT(nj_col->table_field);
+          field_table= nj_col->table_ref->table;
+          if (field_table)
+          {
+            thd->lex->used_tables|= field_table->map;
+            thd->lex->current_select->select_list_tables|=
+              field_table->map;
+            field_table->covering_keys.intersect(field->part_of_key);
+            field_table->used_fields++;
+          }
+        }
+      }
+      else
+        thd->lex->used_tables|= item->used_tables();
+      thd->lex->current_select->cur_pos_in_select_list++;
+    }
+    /*
+      In case of stored tables, all fields are considered as used,
+      while in the case of views, the fields considered as used are the
+      ones marked in setup_tables during fix_fields of view columns.
+      For NATURAL joins, used_tables is updated in the IF above.
+    */
+    if (table)
+      table->used_fields= table->s->fields;
+  }
+  if (found)
+    DBUG_RETURN(FALSE);
+
+  /*
+    TODO: in the case when we skipped all columns because there was a
+    qualified '*', and all columns were coalesced, we have to give a more
+    meaningful message than ER_BAD_TABLE_ERROR.
+  */
+  if (!table_name)
+    my_error(ER_NO_TABLES_USED, MYF(0));
+  else if (!db_name && !thd->db.str)
+    my_error(ER_NO_DB_ERROR, MYF(0));
+  else
+  {
+    char name[FN_REFLEN];
+    my_snprintf(name, sizeof(name), "%s.%s",
+                db_name ? db_name : thd->get_db(), table_name);
+    my_error(ER_BAD_TABLE_ERROR, MYF(0), name);
+  }
+
+  DBUG_RETURN(TRUE);
+}
+
+
+/**
+  Wrap Item_ident
+
+  @param thd             thread handle
+  @param conds           pointer to the condition which should be wrapped
+*/
+
+void wrap_ident(THD *thd, Item **conds)
+{
+  Item_direct_ref_to_ident *wrapper;
+  DBUG_ASSERT((*conds)->type() == Item::FIELD_ITEM || (*conds)->type() == Item::REF_ITEM);
+  Query_arena *arena, backup;
+  arena= thd->activate_stmt_arena_if_needed(&backup);
+  if ((wrapper= new (thd->mem_root) Item_direct_ref_to_ident(thd, (Item_ident *) (*conds))))
+    (*conds)= (Item*) wrapper;
+  if (arena)
+    thd->restore_active_arena(arena, &backup);
+}
+
+/**
+  Prepare ON expression
+
+  @param thd             Thread handle
+  @param table           Pointer to table list
+  @param is_update       Update flag
+
+  @retval TRUE error.
+  @retval FALSE OK.
+*/
+
+bool setup_on_expr(THD *thd, TABLE_LIST *table, bool is_update)
+{
+  uchar buff[STACK_BUFF_ALLOC];			// Max argument in function
+  if (check_stack_overrun(thd, STACK_MIN_SIZE, buff))
+    return TRUE;				// Fatal error flag is set!
+  for(; table; table= table->next_local)
+  {
+    TABLE_LIST *embedded; /* The table at the current level of nesting. */
+    TABLE_LIST *embedding= table; /* The parent nested table reference. */
+    do
+    {
+      embedded= embedding;
+      if (embedded->on_expr)
+      {
+        thd->where="on clause";
+        embedded->on_expr->mark_as_condition_AND_part(embedded);
+        if (embedded->on_expr->fix_fields_if_needed_for_bool(thd,
+                                                           &embedded->on_expr))
+          return TRUE;
+      }
+      /*
+        If it's a semi-join nest, fix its "left expression", as it is used by
+        the SJ-Materialization
+      */
+      if (embedded->sj_subq_pred)
+      {
+        Item **left_expr= embedded->sj_subq_pred->left_exp_ptr();
+        if ((*left_expr)->fix_fields_if_needed(thd, left_expr))
+          return TRUE;
+      }
+
+      embedding= embedded->embedding;
+    }
+    while (embedding &&
+           embedding->nested_join->join_list.head() == embedded);
+
+    if (table->is_merged_derived())
+    {
+      SELECT_LEX *select_lex= table->get_single_select();
+      setup_on_expr(thd, select_lex->get_table_list(), is_update);
+    }
+
+    /* process CHECK OPTION */
+    if (is_update)
+    {
+      TABLE_LIST *view= table->top_table();
+      if (view->effective_with_check)
+      {
+        if (view->prepare_check_option(thd))
+          return TRUE;
+        thd->change_item_tree(&table->check_option, view->check_option);
+      }
+    }
+  }
+  return FALSE;
+}
+
+/*
+  Fix all conditions and outer join expressions.
+
+  SYNOPSIS
+    setup_conds()
+    thd     thread handler
+    tables  list of tables for name resolving (select_lex->table_list)
+    leaves  list of leaves of join table tree (select_lex->leaf_tables)
+    conds   WHERE clause
+
+  DESCRIPTION
+    TODO
+
+  RETURN
+    TRUE  if some error occurred (e.g. out of memory)
+    FALSE if all is OK
+*/
+
+int setup_conds(THD *thd, TABLE_LIST *tables, List<TABLE_LIST> &leaves,
+                COND **conds)
+{
+  SELECT_LEX *select_lex= thd->lex->current_select;
+  TABLE_LIST *table= NULL;	// For HP compilers
+  /*
+    it_is_update set to TRUE when tables of primary SELECT_LEX (SELECT_LEX
+    which belong to LEX, i.e. most up SELECT) will be updated by
+    INSERT/UPDATE/LOAD
+    NOTE: using this condition helps to prevent call of prepare_check_option()
+    from subquery of VIEW, because tables of subquery belongs to VIEW
+    (see condition before prepare_check_option() call)
+  */
+  bool it_is_update= (select_lex == thd->lex->first_select_lex()) &&
+    thd->lex->which_check_option_applicable();
+  bool save_is_item_list_lookup= select_lex->is_item_list_lookup;
+  TABLE_LIST *derived= select_lex->master_unit()->derived;
+  DBUG_ENTER("setup_conds");
+
+  select_lex->is_item_list_lookup= 0;
+
+  thd->column_usage= MARK_COLUMNS_READ;
+  DBUG_PRINT("info", ("thd->column_usage: %d", thd->column_usage));
+  select_lex->cond_count= 0;
+  select_lex->between_count= 0;
+  select_lex->max_equal_elems= 0;
+
+  for (table= tables; table; table= table->next_local)
+  {
+    if (select_lex == thd->lex->first_select_lex() &&
+        select_lex->first_cond_optimization &&
+        table->merged_for_insert &&
+        table->prepare_where(thd, conds, FALSE))
+      goto err_no_arena;
+  }
+
+  if (*conds)
+  {
+    thd->where="where clause";
+    DBUG_EXECUTE("where",
+                 print_where(*conds,
+                             "WHERE in setup_conds",
+                             QT_ORDINARY););
+    /*
+      Wrap alone field in WHERE clause in case it will be outer field of subquery
+      which need persistent pointer on it, but conds could be changed by optimizer
+    */
+    if ((*conds)->type() == Item::FIELD_ITEM && !derived)
+      wrap_ident(thd, conds);
+    (*conds)->mark_as_condition_AND_part(NO_JOIN_NEST);
+    if ((*conds)->fix_fields_if_needed_for_bool(thd, conds))
+      goto err_no_arena;
+  }
+
+  /*
+    Apply fix_fields() to all ON clauses at all levels of nesting,
+    including the ones inside view definitions.
+  */
+  if (setup_on_expr(thd, tables, it_is_update))
+    goto err_no_arena;
+
+  if (!thd->stmt_arena->is_conventional())
+  {
+    /*
+      We are in prepared statement preparation code => we should store
+      WHERE clause changing for next executions.
+
+      We do this ON -> WHERE transformation only once per PS/SP statement.
+    */
+    select_lex->where= *conds;
+  }
+  thd->lex->current_select->is_item_list_lookup= save_is_item_list_lookup;
+  DBUG_RETURN(MY_TEST(thd->is_error()));
+
+err_no_arena:
+  select_lex->is_item_list_lookup= save_is_item_list_lookup;
+  DBUG_RETURN(1);
+}
+
+
+/******************************************************************************
+** Fill a record with data (for INSERT or UPDATE)
+** Returns : 1 if some field has wrong type
+******************************************************************************/
+
+
+/**
+  Fill the fields of a table with the values of an Item list
+
+  @param thd           thread handler
+  @param table_arg     the table that is being modified
+  @param fields        Item_fields list to be filled
+  @param values        values to fill with
+  @param ignore_errors TRUE if we should ignore errors
+  @param update        TRUE if update query
+
+  @details
+    fill_record() may set table->auto_increment_field_not_null and a
+    caller should make sure that it is reset after their last call to this
+    function.
+    default functions are executed for inserts.
+    virtual fields are always updated
+
+  @return Status
+  @retval true An error occurred.
+  @retval false OK.
+*/
+
+bool
+fill_record(THD *thd, TABLE *table_arg, List<Item> &fields, List<Item> &values,
+            bool ignore_errors, bool update)
+{
+  List_iterator_fast<Item> f(fields),v(values);
+  Item *value, *fld;
+  Item_field *field;
+  Field *rfield;
+  TABLE *table;
+  bool only_unvers_fields= update && table_arg->versioned();
+  bool save_abort_on_warning= thd->abort_on_warning;
+  bool save_no_errors= thd->no_errors;
+  DBUG_ENTER("fill_record");
+
+  thd->no_errors= ignore_errors;
+  /*
+    Reset the table->auto_increment_field_not_null as it is valid for
+    only one row.
+  */
+  if (fields.elements)
+    table_arg->auto_increment_field_not_null= FALSE;
+
+  while ((fld= f++))
+  {
+    if (!(field= fld->field_for_view_update()))
+    {
+      my_error(ER_NONUPDATEABLE_COLUMN, MYF(0), fld->name.str);
+      goto err;
+    }
+    value=v++;
+    DBUG_ASSERT(value);
+    rfield= field->field;
+    table= rfield->table;
+    if (table->next_number_field &&
+        rfield->field_index ==  table->next_number_field->field_index)
+      table->auto_increment_field_not_null= TRUE;
+    const bool skip_sys_field= rfield->vers_sys_field(); // TODO: && !thd->vers_modify_history() [MDEV-16546]
+    if ((rfield->vcol_info || skip_sys_field) &&
+        !value->vcol_assignment_allowed_value() &&
+        table->s->table_category != TABLE_CATEGORY_TEMPORARY)
+    {
+      push_warning_printf(thd, Sql_condition::WARN_LEVEL_WARN,
+                          ER_WARNING_NON_DEFAULT_VALUE_FOR_GENERATED_COLUMN,
+                          ER_THD(thd, ER_WARNING_NON_DEFAULT_VALUE_FOR_GENERATED_COLUMN),
+                          rfield->field_name.str, table->s->table_name.str);
+    }
+    if (only_unvers_fields && !rfield->vers_update_unversioned())
+      only_unvers_fields= false;
+
+    if (rfield->stored_in_db())
+    {
+      if (!skip_sys_field &&
+          unlikely(value->save_in_field(rfield, 0) < 0) && !ignore_errors)
+      {
+        my_message(ER_UNKNOWN_ERROR, ER_THD(thd, ER_UNKNOWN_ERROR), MYF(0));
+        goto err;
+      }
+      /*
+        In sql MODE_SIMULTANEOUS_ASSIGNMENT,
+        move field pointer on value stored in record[1]
+        which contains row before update (see MDEV-13417)
+      */
+      if (update && thd->variables.sql_mode & MODE_SIMULTANEOUS_ASSIGNMENT)
+        rfield->move_field_offset((my_ptrdiff_t) (table->record[1] -
+                                                  table->record[0]));
+    }
+    rfield->set_has_explicit_value();
+  }
+
+  if (update && thd->variables.sql_mode & MODE_SIMULTANEOUS_ASSIGNMENT)
+  {
+    // restore fields pointers on record[0]
+    f.rewind();
+    while ((fld= f++))
+    {
+      rfield= fld->field_for_view_update()->field;
+      if (rfield->stored_in_db())
+      {
+        table= rfield->table;
+        rfield->move_field_offset((my_ptrdiff_t) (table->record[0] -
+                                                  table->record[1]));
+      }
+    }
+  }
+
+  if (update)
+    table_arg->evaluate_update_default_function();
+  else
+    if (table_arg->default_field &&
+        table_arg->update_default_fields(ignore_errors))
+      goto err;
+
+  if (table_arg->versioned() && !only_unvers_fields)
+    table_arg->vers_update_fields();
+  /* Update virtual fields */
+  if (table_arg->vfield &&
+      table_arg->update_virtual_fields(table_arg->file, VCOL_UPDATE_FOR_WRITE))
+    goto err;
+  thd->abort_on_warning= save_abort_on_warning;
+  thd->no_errors=        save_no_errors;
+  DBUG_RETURN(thd->is_error());
+err:
+  DBUG_PRINT("error",("got error"));
+  thd->abort_on_warning= save_abort_on_warning;
+  thd->no_errors=        save_no_errors;
+  if (fields.elements)
+    table_arg->auto_increment_field_not_null= FALSE;
+  DBUG_RETURN(TRUE);
+}
+
+
+/**
+  Prepare Item_field's for fill_record_n_invoke_before_triggers()
+
+  This means redirecting from table->field to
+  table->field_to_fill(), if needed.
+*/
+void switch_to_nullable_trigger_fields(List<Item> &items, TABLE *table)
+{
+  Field** field= table->field_to_fill();
+
+ /* True if we have NOT NULL fields and BEFORE triggers */
+  if (field != table->field)
+  {
+    List_iterator_fast<Item> it(items);
+    Item *item;
+
+    while ((item= it++))
+      item->walk(&Item::switch_to_nullable_fields_processor, 1, field);
+    table->triggers->reset_extra_null_bitmap();
+  }
+}
+
+
+/**
+  Prepare Virtual fields and field with default expressions to use
+  trigger fields
+
+  This means redirecting from table->field to
+  table->field_to_fill(), if needed.
+*/
+
+void switch_defaults_to_nullable_trigger_fields(TABLE *table)
+{
+  if (!table->default_field)
+    return; // no defaults
+
+  Field **trigger_field= table->field_to_fill();
+
+ /* True if we have NOT NULL fields and BEFORE triggers */
+  if (*trigger_field != *table->field)
+  {
+    for (Field **field_ptr= table->default_field; *field_ptr ; field_ptr++)
+    {
+      Field *field= (*field_ptr);
+      field->default_value->expr->walk(&Item::switch_to_nullable_fields_processor, 1, trigger_field);
+      *field_ptr= (trigger_field[field->field_index]);
+    }
+  }
+}
+
+
+/**
+  Test NOT NULL constraint after BEFORE triggers
+*/
+static bool not_null_fields_have_null_values(TABLE *table)
+{
+  Field **orig_field= table->field;
+  Field **filled_field= table->field_to_fill();
+
+  if (filled_field != orig_field)
+  {
+    THD *thd=table->in_use;
+    for (uint i=0; i < table->s->fields; i++)
+    {
+      Field *of= orig_field[i];
+      Field *ff= filled_field[i];
+      if (ff != of)
+      {
+        // copy after-update flags to of, copy before-update flags to ff
+        swap_variables(uint32, of->flags, ff->flags);
+        if (ff->is_real_null())
+        {
+          ff->set_notnull(); // for next row WHERE condition in UPDATE
+          if (convert_null_to_field_value_or_error(of) || thd->is_error())
+            return true;
+        }
+      }
+    }
+  }
+
+  return false;
+}
+
+/**
+  Fill fields in list with values from the list of items and invoke
+  before triggers.
+
+  @param thd           thread context
+  @param table         the table that is being modified
+  @param fields        Item_fields list to be filled
+  @param values        values to fill with
+  @param ignore_errors TRUE if we should ignore errors
+  @param event         event type for triggers to be invoked
+
+  @detail
+    This function assumes that fields which values will be set and triggers
+    to be invoked belong to the same table, and that TABLE::record[0] and
+    record[1] buffers correspond to new and old versions of row respectively.
+
+  @return Status
+  @retval true An error occurred.
+  @retval false OK.
+*/
+
+bool
+fill_record_n_invoke_before_triggers(THD *thd, TABLE *table,
+                                     List<Item> &fields,
+                                     List<Item> &values, bool ignore_errors,
+                                     enum trg_event_type event)
+{
+  int result;
+  Table_triggers_list *triggers= table->triggers;
+
+  result= fill_record(thd, table, fields, values, ignore_errors,
+                      event == TRG_EVENT_UPDATE);
+
+  if (!result && triggers)
+  {
+    if (triggers->process_triggers(thd, event, TRG_ACTION_BEFORE,
+                                    TRUE) ||
+        not_null_fields_have_null_values(table))
+      return TRUE;
+
+    /*
+      Re-calculate virtual fields to cater for cases when base columns are
+      updated by the triggers.
+    */
+    if (table->vfield && fields.elements)
+    {
+      Item *fld= (Item_field*) fields.head();
+      Item_field *item_field= fld->field_for_view_update();
+      if (item_field)
+      {
+        DBUG_ASSERT(table == item_field->field->table);
+        result|= table->update_virtual_fields(table->file,
+                                              VCOL_UPDATE_FOR_WRITE);
+      }
+    }
+  }
+  return result;
+}
+
+
+/**
+  Fill the field buffer of a table with the values of an Item list
+  All fields are given a value
+
+  @param thd           thread handler
+  @param table_arg     the table that is being modified
+  @param ptr           pointer on pointer to record of fields
+  @param values        values to fill with
+  @param ignore_errors TRUE if we should ignore errors
+  @param use_value     forces usage of value of the items instead of result
+
+  @details
+    fill_record() may set table->auto_increment_field_not_null and a
+    caller should make sure that it is reset after their last call to this
+    function.
+
+  @return Status
+  @retval true An error occurred.
+  @retval false OK.
+*/
+
+bool
+fill_record(THD *thd, TABLE *table, Field **ptr, List<Item> &values,
+            bool ignore_errors, bool use_value)
+{
+  List_iterator_fast<Item> v(values);
+  List<TABLE> tbl_list;
+  Item *value;
+  Field *field;
+  bool abort_on_warning_saved= thd->abort_on_warning;
+  uint autoinc_index= table->next_number_field
+                        ? table->next_number_field->field_index
+                        : ~0U;
+  DBUG_ENTER("fill_record");
+  if (!*ptr)
+  {
+    /* No fields to update, quite strange!*/
+    DBUG_RETURN(0);
+  }
+
+  /*
+    On INSERT or UPDATE fields are checked to be from the same table,
+    thus we safely can take table from the first field.
+  */
+  DBUG_ASSERT((*ptr)->table == table);
+
+  /*
+    Reset the table->auto_increment_field_not_null as it is valid for
+    only one row.
+  */
+  table->auto_increment_field_not_null= FALSE;
+  while ((field = *ptr++) && ! thd->is_error())
+  {
+    /* Ensure that all fields are from the same table */
+    DBUG_ASSERT(field->table == table);
+
+    if (unlikely(field->invisible))
+      continue;
+
+    value=v++;
+
+    bool vers_sys_field= table->versioned() && field->vers_sys_field();
+
+    if (field->field_index == autoinc_index)
+      table->auto_increment_field_not_null= TRUE;
+    if ((unlikely(field->vcol_info) || (vers_sys_field && !ignore_errors)) &&
+        !value->vcol_assignment_allowed_value() &&
+        table->s->table_category != TABLE_CATEGORY_TEMPORARY)
+    {
+      push_warning_printf(thd, Sql_condition::WARN_LEVEL_WARN,
+                          ER_WARNING_NON_DEFAULT_VALUE_FOR_GENERATED_COLUMN,
+                          ER_THD(thd, ER_WARNING_NON_DEFAULT_VALUE_FOR_GENERATED_COLUMN),
+                          field->field_name.str, table->s->table_name.str);
+      if (vers_sys_field)
+        continue;
+    }
+
+    if (use_value)
+      value->save_val(field);
+    else
+      if (value->save_in_field(field, 0) < 0)
+        goto err;
+    field->set_has_explicit_value();
+  }
+  /* Update virtual fields if there wasn't any errors */
+  if (!thd->is_error())
+  {
+    thd->abort_on_warning= FALSE;
+    if (table->versioned())
+      table->vers_update_fields();
+    if (table->vfield &&
+        table->update_virtual_fields(table->file, VCOL_UPDATE_FOR_WRITE))
+      goto err;
+    thd->abort_on_warning= abort_on_warning_saved;
+  }
+  DBUG_RETURN(thd->is_error());
+
+err:
+  thd->abort_on_warning= abort_on_warning_saved;
+  table->auto_increment_field_not_null= FALSE;
+  DBUG_RETURN(TRUE);
+}
+
+
+/*
+  Fill fields in an array with values from the list of items and invoke
+  before triggers.
+
+  @param thd           thread context
+  @param table         the table that is being modified
+  @param ptr        the fields to be filled
+  @param values        values to fill with
+  @param ignore_errors TRUE if we should ignore errors
+  @param event         event type for triggers to be invoked
+
+  @detail
+    This function assumes that fields which values will be set and triggers
+    to be invoked belong to the same table, and that TABLE::record[0] and
+    record[1] buffers correspond to new and old versions of row respectively.
+
+  @return Status
+  @retval true An error occurred.
+  @retval false OK.
+*/
+
+bool
+fill_record_n_invoke_before_triggers(THD *thd, TABLE *table, Field **ptr,
+                                     List<Item> &values, bool ignore_errors,
+                                     enum trg_event_type event)
+{
+  bool result;
+  Table_triggers_list *triggers= table->triggers;
+
+  result= fill_record(thd, table, ptr, values, ignore_errors, FALSE);
+
+  if (!result && triggers && *ptr)
+    result= triggers->process_triggers(thd, event, TRG_ACTION_BEFORE, TRUE) ||
+            not_null_fields_have_null_values(table);
+  /*
+    Re-calculate virtual fields to cater for cases when base columns are
+    updated by the triggers.
+  */
+  if (!result && triggers && *ptr)
+  {
+    DBUG_ASSERT(table == (*ptr)->table);
+    if (table->vfield)
+      result= table->update_virtual_fields(table->file, VCOL_UPDATE_FOR_WRITE);
+  }
+  return result;
+
+}
+
+
+my_bool mysql_rm_tmp_tables(void)
+{
+  uint i, idx;
+  char	path[FN_REFLEN], *tmpdir, path_copy[FN_REFLEN];
+  MY_DIR *dirp;
+  FILEINFO *file;
+  TABLE_SHARE share;
+  THD *thd;
+  DBUG_ENTER("mysql_rm_tmp_tables");
+
+  if (!(thd= new THD(0)))
+    DBUG_RETURN(1);
+  thd->thread_stack= (char*) &thd;
+  thd->store_globals();
+
+  for (i=0; i<=mysql_tmpdir_list.max; i++)
+  {
+    tmpdir=mysql_tmpdir_list.list[i];
+    /* See if the directory exists */
+    if (!(dirp = my_dir(tmpdir,MYF(MY_WME | MY_DONT_SORT))))
+      continue;
+
+    /* Remove all SQLxxx tables from directory */
+
+    for (idx=0 ; idx < (uint) dirp->number_of_files ; idx++)
+    {
+      file=dirp->dir_entry+idx;
+
+      if (!strncmp(file->name, tmp_file_prefix, tmp_file_prefix_length))
+      {
+        char *ext= fn_ext(file->name);
+        size_t ext_len= strlen(ext);
+        size_t path_len= my_snprintf(path, sizeof(path),
+                                       "%s%c%s", tmpdir, FN_LIBCHAR,
+                                       file->name);
+        if (!strcmp(reg_ext, ext))
+        {
+          /* We should cut file extention before deleting of table */
+          memcpy(path_copy, path, path_len - ext_len);
+          path_copy[path_len - ext_len]= 0;
+          init_tmp_table_share(thd, &share, "", 0, "", path_copy);
+          if (!open_table_def(thd, &share))
+            share.db_type()->drop_table(share.db_type(), path_copy);
+          free_table_share(&share);
+        }
+        /*
+          File can be already deleted by tmp_table.file->delete_table().
+          So we hide error messages which happnes during deleting of these
+          files(MYF(0)).
+        */
+        (void) mysql_file_delete(key_file_misc, path, MYF(0));
+      }
+    }
+    my_dirend(dirp);
+  }
+  delete thd;
+  DBUG_RETURN(0);
+}
+
+
+/*****************************************************************************
+	unireg support functions
+*****************************************************************************/
+
+int setup_ftfuncs(SELECT_LEX *select_lex)
+{
+  List_iterator<Item_func_match> li(*(select_lex->ftfunc_list)),
+                                 lj(*(select_lex->ftfunc_list));
+  Item_func_match *ftf, *ftf2;
+
+  while ((ftf=li++))
+  {
+    if (ftf->fix_index())
+      return 1;
+    lj.rewind();
+    while ((ftf2=lj++) != ftf)
+    {
+      if (ftf->eq(ftf2,1) && !ftf2->master)
+        ftf2->master=ftf;
+    }
+  }
+
+  return 0;
+}
+
+
+void cleanup_ftfuncs(SELECT_LEX *select_lex)
+{
+  List_iterator<Item_func_match> li(*(select_lex->ftfunc_list)),
+                                 lj(*(select_lex->ftfunc_list));
+  Item_func_match *ftf;
+
+  while ((ftf=li++))
+  {
+    ftf->cleanup();
+  }
+}
+
+
+int init_ftfuncs(THD *thd, SELECT_LEX *select_lex, bool no_order)
+{
+  if (select_lex->ftfunc_list->elements)
+  {
+    List_iterator<Item_func_match> li(*(select_lex->ftfunc_list));
+    Item_func_match *ifm;
+
+    while ((ifm=li++))
+      if (unlikely(!ifm->is_fixed()))
+        /*
+          it mean that clause where was FT function was removed, so we have
+          to remove the function from the list.
+        */
+        li.remove();
+      else if (ifm->init_search(thd, no_order))
+	return 1;
+  }
+  return 0;
+}
+
+
+bool is_equal(const LEX_CSTRING *a, const LEX_CSTRING *b)
+{
+  return a->length == b->length && !strncmp(a->str, b->str, a->length);
+}
+
+/*
+  Open and lock system tables for read.
+
+  SYNOPSIS
+    open_system_tables_for_read()
+      thd         Thread context.
+      table_list  List of tables to open.
+
+  NOTES
+    Caller should have used start_new_trans object to start a new
+    transcation when reading system tables.
+
+    Thanks to restrictions which we put on opening and locking of
+    system tables for writing, we can open and lock them for reading
+    even when we already have some other tables open and locked.
+    One should call thd->commit_whole_transaction_and_close_tables()
+    to close systems tables opened with this call.
+
+  NOTES
+   In some situations we  use this function to open system tables for
+   writing. It happens, for examples, with statistical tables when
+   they are updated by an ANALYZE command. In these cases we should
+   guarantee that system tables will not be deadlocked.
+
+  RETURN
+    FALSE   Success
+    TRUE    Error
+*/
+
+bool
+open_system_tables_for_read(THD *thd, TABLE_LIST *table_list)
+{
+  Query_tables_list query_tables_list_backup;
+  LEX *lex= thd->lex;
+  DBUG_ENTER("open_system_tables_for_read");
+  DBUG_ASSERT(thd->internal_transaction());
+
+  /*
+    Besides using new Open_tables_state for opening system tables,
+    we also have to backup and reset/and then restore part of LEX
+    which is accessed by open_tables() in order to determine if
+    prelocking is needed and what tables should be added for it.
+  */
+  lex->reset_n_backup_query_tables_list(&query_tables_list_backup);
+  thd->lex->sql_command= SQLCOM_SELECT;
+
+  /*
+    Only use MYSQL_LOCK_IGNORE_TIMEOUT for tables opened for read.
+    This is to ensure that lock_wait_timeout is honored when trying
+    to update stats tables.
+  */
+  if (open_and_lock_tables(thd, table_list, FALSE,
+                           (MYSQL_OPEN_IGNORE_FLUSH |
+                            MYSQL_OPEN_IGNORE_LOGGING_FORMAT |
+                            (table_list->lock_type < TL_WRITE_ALLOW_WRITE ?
+                             MYSQL_LOCK_IGNORE_TIMEOUT : 0))))
+  {
+    lex->restore_backup_query_tables_list(&query_tables_list_backup);
+    DBUG_RETURN(TRUE);
+  }
+
+  for (TABLE_LIST *tables= table_list; tables; tables= tables->next_global)
+  {
+    DBUG_ASSERT(tables->table->s->table_category == TABLE_CATEGORY_SYSTEM);
+    tables->table->file->row_logging= 0;
+    tables->table->use_all_columns();
+  }
+  lex->restore_backup_query_tables_list(&query_tables_list_backup);
+
+  DBUG_RETURN(FALSE);
+}
+
+/**
+  A helper function to close a mysql.* table opened
+  in an auxiliary THD during bootstrap or in the main
+  connection, when we know that there are no locks
+  held by the connection due to a preceding implicit
+  commit.
+
+  We need this function since we'd like to not
+  just close the system table, but also release
+  the metadata lock on it.
+
+  Note, that in LOCK TABLES mode this function
+  does not release the metadata lock. But in this
+  mode the table can be opened only if it is locked
+  explicitly with LOCK TABLES.
+*/
+
+void
+close_mysql_tables(THD *thd)
+{
+  if (! thd->in_sub_stmt)
+  {
+    trans_commit_stmt(thd);
+    trans_commit(thd);
+  }
+  close_thread_tables(thd);
+  thd->release_transactional_locks();
+}
+
+/*
+  Open and lock one system table for update.
+
+  SYNOPSIS
+    open_system_table_for_update()
+      thd        Thread context.
+      one_table  Table to open.
+
+  NOTES
+    Table opened with this call should closed using close_thread_tables().
+
+  RETURN
+    0	Error
+    #	Pointer to TABLE object of system table
+*/
+
+TABLE *
+open_system_table_for_update(THD *thd, TABLE_LIST *one_table)
+{
+  DBUG_ENTER("open_system_table_for_update");
+
+  TABLE *table= open_ltable(thd, one_table, one_table->lock_type,
+                            MYSQL_LOCK_IGNORE_TIMEOUT);
+  if (table)
+  {
+    DBUG_ASSERT(table->s->table_category == TABLE_CATEGORY_SYSTEM);
+    table->use_all_columns();
+    /* This table instance is not row logged */
+    table->file->row_logging= 0;
+  }
+  DBUG_RETURN(table);
+}
+
+/**
+  Open a log table.
+  Opening such tables is performed internally in the server
+  implementation, and is a 'nested' open, since some tables
+  might be already opened by the current thread.
+  The thread context before this call is saved, and is restored
+  when calling close_log_table().
+  @param thd The current thread
+  @param one_table Log table to open
+  @param backup [out] Temporary storage used to save the thread context
+*/
+TABLE *
+open_log_table(THD *thd, TABLE_LIST *one_table, Open_tables_backup *backup)
+{
+  uint flags= ( MYSQL_OPEN_IGNORE_GLOBAL_READ_LOCK |
+                MYSQL_LOCK_IGNORE_GLOBAL_READ_ONLY |
+                MYSQL_OPEN_IGNORE_FLUSH |
+                MYSQL_LOCK_IGNORE_TIMEOUT |
+                MYSQL_LOCK_LOG_TABLE);
+  TABLE *table;
+  /* Save value that is changed in mysql_lock_tables() */
+  ulonglong save_utime_after_lock= thd->utime_after_lock;
+  DBUG_ENTER("open_log_table");
+
+  thd->reset_n_backup_open_tables_state(backup);
+
+  if ((table= open_ltable(thd, one_table, one_table->lock_type, flags)))
+  {
+    DBUG_ASSERT(table->s->table_category == TABLE_CATEGORY_LOG);
+    DBUG_ASSERT(!table->file->row_logging);
+
+    /* Make sure all columns get assigned to a default value */
+    table->use_all_columns();
+    DBUG_ASSERT(table->s->no_replicate);
+  }
+  else
+    thd->restore_backup_open_tables_state(backup);
+
+  thd->utime_after_lock= save_utime_after_lock;
+  DBUG_RETURN(table);
+}
+
+/**
+  Close a log table.
+  The last table opened by open_log_table()
+  is closed, then the thread context is restored.
+  @param thd The current thread
+  @param backup [in] the context to restore.
+*/
+
+void close_log_table(THD *thd, Open_tables_backup *backup)
+{
+  /*
+    Inform the transaction handler that we are closing the
+    system tables and we don't need the read view anymore.
+  */
+  for (TABLE *table= thd->open_tables ; table ; table= table->next)
+    table->file->extra(HA_EXTRA_PREPARE_FOR_FORCED_CLOSE);
+  close_thread_tables(thd);
+  thd->restore_backup_open_tables_state(backup);
+}
+
+
+/**
+  @brief
+  Remove 'fixed' flag from items in a list
+
+  @param items list of items to un-fix
+
+  @details
+  This function sets to 0 the 'fixed' flag for items in the 'items' list.
+  It's needed to force correct marking of views' fields for INSERT/UPDATE
+  statements.
+*/
+
+void unfix_fields(List<Item> &fields)
+{
+  List_iterator<Item> li(fields);
+  Item *item;
+  while ((item= li++))
+    item->unfix_fields();
+}
+
+
+/**
+  Check result of dynamic column function and issue error if it is needed
+
+  @param rc              The result code of dynamic column function
+
+  @return the result code which was get as an argument\
+*/
+
+int dynamic_column_error_message(enum_dyncol_func_result rc)
+{
+  switch (rc) {
+  case ER_DYNCOL_YES:
+  case ER_DYNCOL_OK:
+  case ER_DYNCOL_TRUNCATED:
+    break; // it is not an error
+  case ER_DYNCOL_FORMAT:
+    my_error(ER_DYN_COL_WRONG_FORMAT, MYF(0));
+    break;
+  case ER_DYNCOL_LIMIT:
+    my_error(ER_DYN_COL_IMPLEMENTATION_LIMIT, MYF(0));
+    break;
+  case ER_DYNCOL_RESOURCE:
+    my_error(ER_OUT_OF_RESOURCES, MYF(0));
+    break;
+  case ER_DYNCOL_DATA:
+    my_error(ER_DYN_COL_DATA, MYF(0));
+    break;
+  case ER_DYNCOL_UNKNOWN_CHARSET:
+    my_error(ER_DYN_COL_WRONG_CHARSET, MYF(0));
+    break;
+  }
+  return rc;
+}
+
+
+/**
+  Turn on the SELECT_DESCRIBE flag for the primary SELECT_LEX of the statement
+  being processed in case the statement is EXPLAIN UPDATE/DELETE.
+
+  @param lex  current LEX
+*/
+
+void promote_select_describe_flag_if_needed(LEX *lex)
+{
+  if (lex->describe)
+    lex->first_select_lex()->options|= SELECT_DESCRIBE;
+}
+
+
+/**
+  @} (end of group Data_Dictionary)
+*/