Adding upstream version 1:10.11.6.upstream/1%10.11.6upstream

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

1 files changed, 2902 insertions, 0 deletions

diff --git a/sql/sql_union.cc b/sql/sql_union.cc
new file mode 100644
index 00000000..6e839409
--- /dev/null
+++ b/sql/sql_union.cc
@@ -0,0 +1,2902 @@
+/* Copyright (c) 2000, 2017, Oracle and/or its affiliates.
+   Copyright (c) 2010, 2020, MariaDB Corporation.
+
+   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 St, Fifth Floor, Boston, MA 02110-1335  USA */
+
+
+/*
+  UNION  of select's
+  UNION's  were introduced by Monty and Sinisa <sinisa@mysql.com>
+*/
+
+#include "mariadb.h"
+#include "sql_priv.h"
+#include "unireg.h"
+#include "sql_union.h"
+#include "sql_select.h"
+#include "sql_cursor.h"
+#include "sql_base.h"                           // fill_record
+#include "filesort.h"                           // filesort_free_buffers
+#include "sql_view.h"
+#include "sql_cte.h"
+#include "item_windowfunc.h"
+
+bool mysql_union(THD *thd, LEX *lex, select_result *result,
+                 SELECT_LEX_UNIT *unit, ulonglong setup_tables_done_option)
+{
+  DBUG_ENTER("mysql_union");
+  bool res;
+  if (!(res= unit->prepare(unit->derived, result, SELECT_NO_UNLOCK |
+                           setup_tables_done_option)))
+    res= unit->exec();
+  res|= unit->cleanup();
+  DBUG_RETURN(res);
+}
+
+
+/***************************************************************************
+** store records in temporary table for UNION
+***************************************************************************/
+
+int select_unit::prepare(List<Item> &list, SELECT_LEX_UNIT *u)
+{
+  unit= u;
+  return 0;
+}
+
+/**
+  This called by SELECT_LEX_UNIT::exec when select changed
+*/
+
+void select_unit::change_select()
+{
+  uint current_select_number= thd->lex->current_select->select_number;
+  DBUG_ENTER("select_unit::change_select");
+  DBUG_PRINT("enter", ("select in unit change: %u -> %u",
+                       curr_sel, current_select_number));
+  DBUG_ASSERT(curr_sel != current_select_number);
+  curr_sel= current_select_number;
+  /* New SELECT processing starts */
+  DBUG_ASSERT(table->file->inited == 0);
+  step= thd->lex->current_select->get_linkage();
+  switch (step)
+  {
+  case INTERSECT_TYPE:
+    prev_step= curr_step;
+    curr_step= current_select_number;
+    break;
+  case EXCEPT_TYPE:
+    break;
+  default:
+    step= UNION_TYPE;
+    break;
+  }
+  DBUG_VOID_RETURN;
+}
+
+/**
+  Fill temporary tables for UNION/EXCEPT/INTERSECT
+
+  @Note
+UNION:
+  just add records to the table (with 'counter' field first if INTERSECT
+  present in the sequence).
+EXCEPT:
+  looks for the record in the table (with 'counter' field first if
+  INTERSECT present in the sequence) and delete it if found
+INTERSECT:
+  looks for the same record with 'counter' field of previous operation,
+  put as a 'counter' number of the current SELECT.
+    We scan the table and remove all records which marked with not last
+  'counter' after processing all records in send_eof and only if it last
+  SELECT of sequence of INTERSECTS.
+
+  @param values          List of record items to process.
+
+  @retval  0 - OK
+  @retval -1 - duplicate
+  @retval  1 - error
+*/
+int select_unit::send_data(List<Item> &values)
+{
+  int rc= 0;
+  int not_reported_error= 0;
+
+  if (table->no_rows_with_nulls)
+    table->null_catch_flags= CHECK_ROW_FOR_NULLS_TO_REJECT;
+
+  fill_record(thd, table, table->field + addon_cnt, values, true, false);
+  /* set up initial values for records to be written */
+  if (addon_cnt && step == UNION_TYPE)
+  {
+    DBUG_ASSERT(addon_cnt == 1);
+    table->field[0]->store((longlong) curr_step, 1);
+  }
+
+  if (unlikely(thd->is_error()))
+  {
+    rc= 1;
+    if (unlikely(not_reported_error))
+    {
+      DBUG_ASSERT(rc);
+      table->file->print_error(not_reported_error, MYF(0));
+    }
+    return rc;
+  }
+  if (table->no_rows_with_nulls)
+  {
+    table->null_catch_flags&= ~CHECK_ROW_FOR_NULLS_TO_REJECT;
+    if (table->null_catch_flags)
+    {
+      rc= 0;
+      if (unlikely(not_reported_error))
+      {
+        DBUG_ASSERT(rc);
+        table->file->print_error(not_reported_error, MYF(0));
+      }
+      return rc;
+    }
+  }
+
+  /* select_unit::change_select() change step & Co correctly for each SELECT */
+  int find_res;
+  switch (step)
+  {
+  case UNION_TYPE:
+    rc= write_record();
+    /* no reaction with conversion */
+    if (rc == -2)
+      rc= 0;
+    break;
+
+  case EXCEPT_TYPE:
+    /*
+      The temporary table uses very first index or constrain for
+      checking unique constrain.
+    */
+    if (!(find_res= table->file->find_unique_row(table->record[0], 0)))
+      rc= delete_record();
+    else
+      rc= not_reported_error= (find_res != 1);
+    break;
+  case INTERSECT_TYPE:
+    /*
+      The temporary table uses very first index or constrain for
+      checking unique constrain.
+    */
+    if (!(find_res= table->file->find_unique_row(table->record[0], 0)))
+    {
+      DBUG_ASSERT(!table->triggers);
+      if (table->field[0]->val_int() == prev_step)
+      {
+        not_reported_error= update_counter(table->field[0], curr_step);
+        rc= MY_TEST(not_reported_error);
+        DBUG_ASSERT(rc != HA_ERR_RECORD_IS_THE_SAME);
+      }
+    }
+    else
+      rc= not_reported_error= (find_res != 1);
+    break;
+  default:
+    DBUG_ASSERT(0);
+  }
+
+  if (unlikely(not_reported_error))
+  {
+    DBUG_ASSERT(rc);
+    table->file->print_error(not_reported_error, MYF(0));
+  }
+  return rc;
+}
+
+bool select_unit::send_eof()
+{
+  if (step != INTERSECT_TYPE ||
+      (thd->lex->current_select->next_select() &&
+       thd->lex->current_select->next_select()->get_linkage() == INTERSECT_TYPE))
+  {
+    /*
+      it is not INTERSECT or next SELECT in the sequence is INTERSECT so no
+      need filtering (the last INTERSECT in this sequence of intersects will
+      filter).
+    */
+    return 0;
+  }
+
+  /*
+    It is last select in the sequence of INTERSECTs so we should filter out
+    all records except marked with actual counter.
+
+   TODO: as optimization for simple case this could be moved to
+   'fake_select' WHERE condition
+  */
+  int error;
+
+  if (table->file->ha_rnd_init_with_error(1))
+    return 1;
+  do
+  {
+    error= table->file->ha_rnd_next(table->record[0]);
+    if (unlikely(error))
+    {
+      if (error == HA_ERR_END_OF_FILE)
+      {
+        error= 0;
+        break;
+      }
+      break;
+    }
+    if (table->field[0]->val_int() != curr_step)
+      error= delete_record();
+  } while (!error);
+  table->file->ha_rnd_end();
+
+  if (unlikely(error))
+    table->file->print_error(error, MYF(0));
+
+  return(MY_TEST(error));
+}
+
+
+int select_union_recursive::send_data(List<Item> &values)
+{
+
+  int rc;
+  bool save_abort_on_warning= thd->abort_on_warning;
+  enum_check_fields save_count_cuted_fields= thd->count_cuted_fields;
+  long save_counter;
+
+  /*
+    For recursive CTE's give warnings for wrong field info
+    However, we don't do that for CREATE TABLE ... SELECT or INSERT ... SELECT
+    as the upper level code for these handles setting of abort_on_warning
+    depending on if 'IGNORE' is used.
+  */
+  if (thd->lex->sql_command != SQLCOM_CREATE_TABLE &&
+      thd->lex->sql_command != SQLCOM_INSERT_SELECT)
+    thd->abort_on_warning= thd->is_strict_mode();
+  thd->count_cuted_fields= CHECK_FIELD_WARN;
+  save_counter= thd->get_stmt_da()->set_current_row_for_warning(++row_counter);
+  rc= select_unit::send_data(values);
+  thd->get_stmt_da()->set_current_row_for_warning(save_counter);
+  thd->count_cuted_fields= save_count_cuted_fields;
+  thd->abort_on_warning= save_abort_on_warning;
+
+  if (rc == 0 &&
+      write_err != HA_ERR_FOUND_DUPP_KEY &&
+      write_err != HA_ERR_FOUND_DUPP_UNIQUE)
+  { 
+    int err;
+    DBUG_ASSERT(incr_table->s->reclength == table->s->reclength ||
+               incr_table->s->reclength == table->s->reclength - MARIA_UNIQUE_HASH_LENGTH);
+    if ((err= incr_table->file->ha_write_tmp_row(table->record[0])))
+    {
+      bool is_duplicate;
+      rc= create_internal_tmp_table_from_heap(thd, incr_table,
+                                              tmp_table_param.start_recinfo, 
+                                              &tmp_table_param.recinfo,
+					      err, 1, &is_duplicate);
+    }
+  }
+  
+  return rc;
+}
+
+
+bool select_unit::flush()
+{
+  int error;
+  if (unlikely((error=table->file->extra(HA_EXTRA_NO_CACHE))))
+  {
+    table->file->print_error(error, MYF(0));
+    return 1;
+  }
+  return 0;
+}
+
+
+/*
+  Create a temporary table to store the result of select_union.
+
+  SYNOPSIS
+    select_unit::create_result_table()
+      thd                thread handle
+      column_types       a list of items used to define columns of the
+                         temporary table
+      is_union_distinct  if set, the temporary table will eliminate
+                         duplicates on insert
+      options            create options
+      table_alias        name of the temporary table
+      bit_fields_as_long convert bit fields to ulonglong
+      create_table       whether to physically create result table
+      keep_row_order     keep rows in order as they were inserted
+      hidden             number of hidden fields (for INTERSECT)
+                         plus one for `ALL`
+
+  DESCRIPTION
+    Create a temporary table that is used to store the result of a UNION,
+    derived table, or a materialized cursor.
+
+  RETURN VALUE
+    0                    The table has been created successfully.
+    1                    create_tmp_table failed.
+*/
+
+bool
+select_unit::create_result_table(THD *thd_arg, List<Item> *column_types,
+                                  bool is_union_distinct, ulonglong options,
+                                 const LEX_CSTRING *alias,
+                                  bool bit_fields_as_long, bool create_table,
+                                  bool keep_row_order,
+                                  uint hidden)
+{
+  DBUG_ASSERT(table == 0);
+  tmp_table_param.init();
+  tmp_table_param.field_count= column_types->elements;
+  tmp_table_param.func_count= tmp_table_param.field_count;
+  tmp_table_param.bit_fields_as_long= bit_fields_as_long;
+  tmp_table_param.hidden_field_count= hidden;
+
+  if (! (table= create_tmp_table(thd_arg, &tmp_table_param, *column_types,
+                                 (ORDER*) 0, is_union_distinct, 1,
+                                 options, HA_POS_ERROR, alias,
+                                 !create_table, keep_row_order)))
+    return TRUE;
+
+  table->keys_in_use_for_query.clear_all();
+  for (uint i=0; i < table->s->fields; i++)
+    table->field[i]->flags &= ~(PART_KEY_FLAG | PART_INDIRECT_KEY_FLAG);
+
+  if (create_table)
+  {
+    table->file->extra(HA_EXTRA_WRITE_CACHE);
+    table->file->extra(HA_EXTRA_IGNORE_DUP_KEY);
+  }
+  return FALSE;
+}
+
+bool
+select_union_recursive::create_result_table(THD *thd_arg,
+                                            List<Item> *column_types,
+                                            bool is_union_distinct,
+                                            ulonglong options,
+                                            const LEX_CSTRING *alias,
+                                            bool bit_fields_as_long,
+                                            bool create_table,
+                                            bool keep_row_order,
+                                            uint hidden)
+{
+  if (select_unit::create_result_table(thd_arg, column_types,
+                                       is_union_distinct, options,
+                                       &empty_clex_str, bit_fields_as_long,
+                                       create_table, keep_row_order,
+                                       hidden))
+    return true;
+  
+  incr_table_param.init();
+  incr_table_param.field_count= incr_table_param.func_count=
+    column_types->elements;
+  incr_table_param.bit_fields_as_long= bit_fields_as_long;
+  if (! (incr_table= create_tmp_table(thd_arg, &incr_table_param, *column_types,
+                                      (ORDER*) 0, false, 1,
+                                      options, HA_POS_ERROR, &empty_clex_str,
+                                      true, keep_row_order)))
+    return true;
+
+  incr_table->keys_in_use_for_query.clear_all();
+  for (uint i=0; i < table->s->fields; i++)
+    incr_table->field[i]->flags &= ~(PART_KEY_FLAG | PART_INDIRECT_KEY_FLAG);
+
+  return false;
+}
+
+
+/*
+  @brief
+    Write a record
+
+  @retval
+    -2   conversion happened
+    -1  found a duplicate key
+    0   no error
+    1   if an error is reported
+*/
+
+int select_unit::write_record()
+{
+  if (unlikely((write_err= table->file->ha_write_tmp_row(table->record[0]))))
+  {
+    if (write_err == HA_ERR_FOUND_DUPP_KEY)
+    {
+      /*
+        Inform upper level that we found a duplicate key, that should not
+        be counted as part of limit
+      */
+      return -1;
+    }
+    bool is_duplicate= false;
+    /* create_internal_tmp_table_from_heap will generate error if needed */
+    if (table->file->is_fatal_error(write_err, HA_CHECK_DUP))
+    {
+      if (!create_internal_tmp_table_from_heap(thd, table,
+                                              tmp_table_param.start_recinfo,
+                                              &tmp_table_param.recinfo,
+                                              write_err, 1, &is_duplicate))
+      {
+        return -2;
+      }
+      else
+      {
+        return 1;
+      }
+    }
+    if (is_duplicate)
+    {
+      return -1;
+    }
+  }
+  return 0;
+}
+
+
+/*
+  @brief
+    Update counter for a record
+
+  @retval
+    0   no error
+    -1  error occurred
+*/
+
+int select_unit::update_counter(Field* counter, longlong value)
+{
+  store_record(table, record[1]);
+  counter->store(value, 0);
+  int error= table->file->ha_update_tmp_row(table->record[1],
+                                        table->record[0]);
+  return error;
+}
+
+
+/*
+  @brief
+    Try to disable index
+  
+  @retval
+    true    index is disabled this time
+    false   this time did not disable the index
+*/
+
+bool select_unit_ext::disable_index_if_needed(SELECT_LEX *curr_sl)
+{ 
+  if (is_index_enabled && 
+      (curr_sl == curr_sl->master_unit()->union_distinct || 
+        !curr_sl->next_select()) )
+  {
+    is_index_enabled= false;
+    if (table->file->ha_disable_indexes(HA_KEY_SWITCH_ALL))
+      return false;
+    table->no_keyread=1;
+    return true;
+  }
+  return false;
+}
+
+/*
+  @brief
+    Unfold a record
+
+  @retval
+    0   no error
+    -1  conversion happened
+*/
+
+int select_unit_ext::unfold_record(ha_rows cnt)
+{
+
+  DBUG_ASSERT(cnt > 0);
+  int error= 0;
+  bool is_convertion_happened= false;
+  while (--cnt)
+  {
+    error= write_record();
+    if (error == -2)
+    {
+      is_convertion_happened= true;
+      error= -1;
+    }
+  }
+  if (is_convertion_happened)
+    return -1;
+  return error;
+}
+
+/*
+  @brief
+    Delete a record
+
+  @retval
+    0   no error
+    1   if an error is reported
+*/
+
+int select_unit::delete_record()
+{
+  DBUG_ASSERT(!table->triggers);
+  table->status|= STATUS_DELETED;
+  int not_reported_error= table->file->ha_delete_tmp_row(table->record[0]);
+  return MY_TEST(not_reported_error);
+}
+
+/**
+  Reset and empty the temporary table that stores the materialized query
+  result.
+
+  @note The cleanup performed here is exactly the same as for the two temp
+  tables of JOIN - exec_tmp_table_[1 | 2].
+*/
+
+void select_unit::cleanup()
+{
+  table->file->extra(HA_EXTRA_RESET_STATE);
+  table->file->ha_delete_all_rows();
+}
+
+
+/*
+  @brief
+    Set up value needed by send_data() and send_eof()
+
+  @detail
+    - For EXCEPT we will decrease the counter by one
+    and INTERSECT / UNION we increase the counter.
+
+    - For INTERSECT we will modify the second extra field (intersect counter)
+    and for EXCEPT / UNION we modify the first (duplicate counter)
+*/
+
+void select_unit_ext::change_select()
+{
+  select_unit::change_select();
+  switch(step){
+  case UNION_TYPE:
+    increment= 1;
+    curr_op_type= UNION_DISTINCT;
+    break;
+  case EXCEPT_TYPE:
+    increment= -1;
+    curr_op_type= EXCEPT_DISTINCT;
+    break;
+  case INTERSECT_TYPE:
+    increment= 1;
+    curr_op_type= INTERSECT_DISTINCT;
+    break;
+  default: DBUG_ASSERT(0);
+  }
+  if (!thd->lex->current_select->distinct)
+    /* change type from DISTINCT to ALL */
+    curr_op_type= (set_op_type)(curr_op_type + 1);
+
+  duplicate_cnt= table->field[addon_cnt - 1];
+  if (addon_cnt == 2)
+    additional_cnt= table->field[addon_cnt - 2];
+  else
+    additional_cnt= NULL;
+}
+
+
+/*
+  @brief
+    Fill temporary tables for operations need extra fields
+
+  @detail
+    - If this operation is not distinct, we try to find it and increase the
+    counter by "increment" setted in select_unit_ext::change_select().
+
+    - If it is distinct, for UNION we write this record; for INTERSECT we
+    try to find it and increase the intersect counter if found; for EXCEPT
+    we try to find it and delete that record if found.
+
+*/
+
+int select_unit_ext::send_data(List<Item> &values)
+{
+  int rc= 0;
+  int not_reported_error= 0;
+  int find_res;
+
+  if (table->no_rows_with_nulls)
+    table->null_catch_flags= CHECK_ROW_FOR_NULLS_TO_REJECT;
+
+  fill_record(thd, table, table->field + addon_cnt, values, true, false);
+  /* set up initial values for records to be written */
+  if ( step == UNION_TYPE )
+  {
+    /* set duplicate counter to 1 */
+    duplicate_cnt->store((longlong) 1, 1);
+    /* set the other counter to 0 */
+    if (curr_op_type == INTERSECT_ALL)
+      additional_cnt->store((longlong) 0, 1);
+  }
+
+  if (unlikely(thd->is_error()))
+  {
+    rc= 1;
+    if (unlikely(not_reported_error))
+    {
+      DBUG_ASSERT(rc);
+      table->file->print_error(not_reported_error, MYF(0));
+    }
+    return rc;
+  }
+  if (table->no_rows_with_nulls)
+  {
+    table->null_catch_flags&= ~CHECK_ROW_FOR_NULLS_TO_REJECT;
+    if (table->null_catch_flags)
+    {
+      if (unlikely(not_reported_error))
+      {
+        DBUG_ASSERT(rc);
+        table->file->print_error(not_reported_error, MYF(0));
+      }
+      return rc;
+    }
+  }
+
+  switch(curr_op_type)
+  {
+  case UNION_ALL:
+    if (!is_index_enabled ||
+      (find_res= table->file->find_unique_row(table->record[0], 0)))
+    {
+      rc= write_record();
+      /* no reaction with conversion */
+      if (rc == -2)
+        rc= 0;
+    }
+    else
+    {
+      longlong cnt= duplicate_cnt->val_int() + increment;
+      not_reported_error= update_counter(duplicate_cnt, cnt);
+      DBUG_ASSERT(!table->triggers);
+      rc= MY_TEST(not_reported_error);
+    }
+    break;
+
+  case EXCEPT_ALL:
+    if (!(find_res= table->file->find_unique_row(table->record[0], 0)))
+    {
+      longlong cnt= duplicate_cnt->val_int() + increment;
+      if (cnt == 0)
+        rc= delete_record();
+      else
+      {
+        not_reported_error= update_counter(duplicate_cnt, cnt);
+        DBUG_ASSERT(!table->triggers);
+        rc= MY_TEST(not_reported_error);
+      }
+    }
+    break;
+
+  case INTERSECT_ALL:
+    if (!(find_res= table->file->find_unique_row(table->record[0], 0)))
+    {
+      longlong cnt= duplicate_cnt->val_int() + increment;
+      if (cnt <= additional_cnt->val_int())
+      {
+        not_reported_error= update_counter(duplicate_cnt, cnt);
+        DBUG_ASSERT(!table->triggers);
+        rc= MY_TEST(not_reported_error);
+      }
+    }
+    break;
+
+  case UNION_DISTINCT:
+    rc= write_record();
+    /* no reaction with conversion */
+    if (rc == -2)
+      rc= 0;
+    break;
+
+  case EXCEPT_DISTINCT:
+    if (!(find_res= table->file->find_unique_row(table->record[0], 0)))
+      rc= delete_record();
+    else
+      rc= not_reported_error= (find_res != 1);
+    break;
+
+  case INTERSECT_DISTINCT:
+    if (!(find_res= table->file->find_unique_row(table->record[0], 0)))
+    {
+      if (additional_cnt->val_int() == prev_step)
+      {
+        not_reported_error= update_counter(additional_cnt, curr_step);
+        rc= MY_TEST(not_reported_error);
+        DBUG_ASSERT(rc != HA_ERR_RECORD_IS_THE_SAME);
+      }
+      else if (additional_cnt->val_int() != curr_step)
+        rc= delete_record();
+    }
+    else
+      rc= not_reported_error= (find_res != 1);
+    break;
+
+  default:
+    DBUG_ASSERT(0);
+  }
+
+  if (unlikely(not_reported_error))
+  {
+    DBUG_ASSERT(rc);
+    table->file->print_error(not_reported_error, MYF(0));
+  }
+  return rc;
+}
+
+
+/*
+  @brief
+    Do post-operation after a operator
+
+  @detail
+    We need to scan in these cases:
+      - If this operation is DISTINCT and next is ALL,
+        duplicate counter needs to be set to 1.
+      - If this operation is INTERSECT ALL and counter needs to be updated.
+      - If next operation is INTERSECT ALL,
+        set up the second extra field (called "intersect_counter") to 0.
+        this extra field counts records in the second operand.
+
+    If this operation is equal to "union_distinct" or is the last operation,
+    we'll disable index. Then if this operation is ALL we'll unfold records.
+*/
+
+bool select_unit_ext::send_eof()
+{
+  int error= 0;
+  SELECT_LEX *curr_sl= thd->lex->current_select;
+  SELECT_LEX *next_sl= curr_sl->next_select();
+  bool is_next_distinct= next_sl && next_sl->distinct;
+  bool is_next_intersect_all=
+                        next_sl &&
+                        next_sl->get_linkage() == INTERSECT_TYPE &&
+                        !next_sl->distinct;
+  bool need_unfold= (disable_index_if_needed(curr_sl) &&
+                    !curr_sl->distinct);
+
+  if (((curr_sl->distinct && !is_next_distinct) ||
+      curr_op_type == INTERSECT_ALL ||
+      is_next_intersect_all) &&
+      !need_unfold)
+  {
+    if (!next_sl)
+      DBUG_ASSERT(curr_op_type != INTERSECT_ALL);
+    bool need_update_row;
+    if (unlikely(table->file->ha_rnd_init_with_error(1)))
+      return 1;
+    do
+    {
+      need_update_row= false;
+      if (unlikely(error= table->file->ha_rnd_next(table->record[0])))
+      {
+        if (error == HA_ERR_END_OF_FILE)
+        {
+          error= 0;
+          break;
+        }
+        break;
+      }
+      store_record(table, record[1]);
+
+      if (curr_sl->distinct && !is_next_distinct)
+      {
+        /* set duplicate counter to 1 if next operation is ALL */
+        duplicate_cnt->store(1, 0);
+        need_update_row= true;
+      }
+
+      if (is_next_intersect_all)
+      {
+        longlong d_cnt_val= duplicate_cnt->val_int();
+        if (d_cnt_val == 0)
+          error= delete_record();
+        else
+        {
+          if (curr_op_type == INTERSECT_ALL)
+          {
+            longlong a_cnt_val= additional_cnt->val_int();
+            if (a_cnt_val < d_cnt_val)
+              d_cnt_val= a_cnt_val;
+          }
+          additional_cnt->store(d_cnt_val, 0);
+          duplicate_cnt->store((longlong)0, 0);
+          need_update_row= true;
+        }
+      }
+
+      if (need_update_row)
+        error= table->file->ha_update_tmp_row(table->record[1],
+                                              table->record[0]);
+    } while (likely(!error));
+    table->file->ha_rnd_end();
+  }
+
+  /*  unfold */
+  else if (need_unfold)
+  {
+    /* unfold if is ALL operation */
+    ha_rows dup_cnt;
+    if (unlikely(table->file->ha_rnd_init_with_error(1)))
+      return 1;
+    do
+    {
+      if (unlikely(error= table->file->ha_rnd_next(table->record[0])))
+      {
+        if (error == HA_ERR_END_OF_FILE)
+        {
+          error= 0;
+          break;
+        }
+        break;
+      }
+      dup_cnt= (ha_rows)duplicate_cnt->val_int();
+      /* delete record if not exist in the second operand */
+      if (dup_cnt == 0)
+      {
+        error= delete_record();
+        continue;
+      }
+      if (curr_op_type == INTERSECT_ALL)
+      {
+        ha_rows add_cnt= (ha_rows)additional_cnt->val_int();
+        if (dup_cnt > add_cnt && add_cnt > 0)
+          dup_cnt= (ha_rows)add_cnt;
+      }
+
+      if (dup_cnt == 1)
+        continue;
+
+      duplicate_cnt->store((longlong)1, 0);
+      if (additional_cnt)
+        additional_cnt->store((longlong)0, 0);
+      error= table->file->ha_update_tmp_row(table->record[1],
+                                            table->record[0]);
+      if (unlikely(error))
+        break;
+
+      if (unfold_record(dup_cnt) == -1)
+      {
+        /* restart the scan */
+        if (unlikely(table->file->ha_rnd_init_with_error(1)))
+          return 1;
+
+        duplicate_cnt= table->field[addon_cnt - 1];
+        if (addon_cnt == 2)
+          additional_cnt= table->field[addon_cnt - 2];
+        else
+          additional_cnt= NULL;
+        continue;
+      }
+    } while (likely(!error));
+    table->file->ha_rnd_end();
+  }
+
+  /* Clean up table buffers for the next set operation from pipeline */
+  if (next_sl)
+    restore_record(table,s->default_values);
+
+  if (unlikely(error))
+    table->file->print_error(error, MYF(0));
+
+  return (MY_TEST(error));
+}
+
+void select_union_recursive::cleanup()
+{
+  if (table)
+  {
+    select_unit::cleanup();
+    free_tmp_table(thd, table);
+  }
+
+  if (incr_table)
+  {
+    if (incr_table->is_created())
+    {
+      incr_table->file->extra(HA_EXTRA_RESET_STATE);
+      incr_table->file->ha_delete_all_rows();
+    }
+    free_tmp_table(thd, incr_table);
+  }
+
+  List_iterator<TABLE_LIST> it(rec_table_refs);
+  TABLE_LIST *tbl;
+  while ((tbl= it++))
+  {
+    TABLE *tab= tbl->table;
+    if (tab->is_created())
+    {
+      tab->file->extra(HA_EXTRA_RESET_STATE);
+      tab->file->ha_delete_all_rows();
+    }
+    /*
+      The table will be closed later in close_thread_tables(),
+      because it might be used in the statements like
+      ANALYZE WITH r AS (...) SELECT * from r
+      where r is defined through recursion.
+    */
+    tab->next= thd->rec_tables;
+    thd->rec_tables= tab;
+    tbl->derived_result= 0;
+  }
+  row_counter= 0;
+}
+
+
+/**
+  Replace the current result with new_result and prepare it.  
+
+  @param new_result New result pointer
+
+  @retval FALSE Success
+  @retval TRUE  Error
+*/
+
+bool select_union_direct::change_result(select_result *new_result)
+{
+  result= new_result;
+  return (result->prepare(unit->types, unit) || result->prepare2(NULL));
+}
+
+
+bool select_union_direct::postponed_prepare(List<Item> &types)
+{
+  if (result != NULL)
+    return (result->prepare(types, unit) || result->prepare2(NULL));
+  else
+    return false;
+}
+
+
+bool select_union_direct::send_result_set_metadata(List<Item> &list, uint flags)
+{
+  if (done_send_result_set_metadata)
+    return false;
+  done_send_result_set_metadata= true;
+
+  /*
+    Set global offset and limit to be used in send_data(). These can
+    be variables in prepared statements or stored programs, so they
+    must be reevaluated for each execution.
+   */
+  offset= unit->global_parameters()->get_offset();
+  limit= unit->global_parameters()->get_limit();
+  if (limit + offset >= limit)
+    limit+= offset;
+  else
+    limit= HA_POS_ERROR; /* purecov: inspected */
+
+  return result->send_result_set_metadata(unit->types, flags);
+}
+
+
+int select_union_direct::send_data(List<Item> &items)
+{
+  if (!limit)
+    return false;
+  limit--;
+  if (offset)
+  {
+    offset--;
+    return false;
+  }
+
+  send_records++;
+  fill_record(thd, table, table->field, items, true, false);
+  if (unlikely(thd->is_error()))
+    return true; /* purecov: inspected */
+
+  return result->send_data(unit->item_list);
+}
+
+
+bool select_union_direct::initialize_tables (JOIN *join)
+{
+  if (done_initialize_tables)
+    return false;
+  done_initialize_tables= true;
+
+  return result->initialize_tables(join);
+}
+
+
+bool select_union_direct::send_eof()
+{
+  // Reset for each SELECT_LEX, so accumulate here
+  limit_found_rows+= thd->limit_found_rows;
+
+  if (unit->thd->lex->current_select == last_select_lex)
+  {
+    thd->limit_found_rows= limit_found_rows;
+
+    // Reset and make ready for re-execution
+    done_send_result_set_metadata= false;
+    done_initialize_tables= false;
+
+    return result->send_eof();
+  }
+  else
+    return false;
+}
+
+
+/*
+  initialization procedures before fake_select_lex preparation()
+
+  SYNOPSIS
+    st_select_lex_unit::init_prepare_fake_select_lex()
+    thd		- thread handler
+    first_execution - TRUE at the first execution of the union 
+
+  RETURN
+    options of SELECT
+*/
+
+void
+st_select_lex_unit::init_prepare_fake_select_lex(THD *thd_arg,
+                                                  bool first_execution) 
+{
+  thd_arg->lex->current_select= fake_select_lex;
+  fake_select_lex->table_list.link_in_list(&result_table_list,
+                                           &result_table_list.next_local);
+  fake_select_lex->context.table_list= 
+    fake_select_lex->context.first_name_resolution_table= 
+    fake_select_lex->get_table_list();
+  /*
+    The flag fake_select_lex->first_execution indicates whether this is
+    called at the first execution of the statement, while first_execution
+    shows whether this is called at the first execution of the union that
+    may form just a subselect.
+  */
+  if ((fake_select_lex->changed_elements & TOUCHED_SEL_COND) &&
+      first_execution)
+  {
+    for (ORDER *order= global_parameters()->order_list.first;
+         order;
+         order= order->next)
+      order->item= &order->item_ptr;
+  }
+}
+
+
+bool st_select_lex_unit::prepare_join(THD *thd_arg, SELECT_LEX *sl,
+                                      select_result *tmp_result,
+                                      ulonglong additional_options,
+                                      bool is_union_select)
+{
+  DBUG_ENTER("st_select_lex_unit::prepare_join");
+  TABLE_LIST *derived= sl->master_unit()->derived;
+  bool can_skip_order_by;
+  sl->options|=  SELECT_NO_UNLOCK;
+  JOIN *join= new JOIN(thd_arg, sl->item_list,
+                       (sl->options | thd_arg->variables.option_bits |
+                        additional_options),
+                       tmp_result);
+  if (!join)
+    DBUG_RETURN(true);
+
+  thd_arg->lex->current_select= sl;
+
+  can_skip_order_by= (is_union_select && !(sl->braces &&
+                                           sl->limit_params.explicit_limit) &&
+                      !thd->lex->with_rownum);
+
+  saved_error= join->prepare(sl->table_list.first,
+                             (derived && derived->merged ? NULL : sl->where),
+                             (can_skip_order_by ? 0 :
+                              sl->order_list.elements) +
+                             sl->group_list.elements,
+                             can_skip_order_by ?
+                             NULL : sl->order_list.first,
+                             can_skip_order_by,
+                             sl->group_list.first,
+                             sl->having,
+                             (is_union_select ? NULL :
+                              thd_arg->lex->proc_list.first),
+                             sl, this);
+
+  last_procedure= join->procedure;
+
+  if (unlikely(saved_error || (saved_error= thd_arg->is_fatal_error)))
+    DBUG_RETURN(true);
+  /*
+    Remove all references from the select_lex_units to the subqueries that
+    are inside the ORDER BY clause.
+  */
+  if (can_skip_order_by)
+  {
+    for (ORDER *ord= (ORDER *)sl->order_list.first; ord; ord= ord->next)
+    {
+      (*ord->item)->walk(&Item::eliminate_subselect_processor, FALSE, NULL);
+    }
+  }
+  DBUG_RETURN(false);
+}
+
+
+/**
+  Aggregate data type handlers for the "count" leftmost UNION parts.
+*/
+bool st_select_lex_unit::join_union_type_handlers(THD *thd_arg,
+                                                  Type_holder *holders,
+                                                  uint count)
+{
+  DBUG_ENTER("st_select_lex_unit::join_union_type_handlers");
+  SELECT_LEX *first_sl= first_select(), *sl= first_sl;
+  for (uint i= 0; i < count ; sl= sl->next_select(), i++)
+  {
+    Item *item;
+    List_iterator_fast<Item> it(sl->item_list);
+    for (uint pos= 0; (item= it++); pos++)
+    {
+      const Type_handler *item_type_handler= item->real_type_handler();
+      if (sl == first_sl)
+        holders[pos].set_handler(item_type_handler);
+      else
+      {
+        DBUG_ASSERT(first_sl->item_list.elements == sl->item_list.elements);
+        if (holders[pos].aggregate_for_result(item_type_handler))
+        {
+          my_error(ER_ILLEGAL_PARAMETER_DATA_TYPES2_FOR_OPERATION, MYF(0),
+                   holders[pos].type_handler()->name().ptr(),
+                   item_type_handler->name().ptr(),
+                   "UNION");
+          DBUG_RETURN(true);
+        }
+      }
+    }
+  }
+  DBUG_RETURN(false);
+}
+
+
+/**
+  Aggregate data type attributes for the "count" leftmost UNION parts.
+*/
+bool st_select_lex_unit::join_union_type_attributes(THD *thd_arg,
+                                                    Type_holder *holders,
+                                                    uint count)
+{
+  DBUG_ENTER("st_select_lex_unit::join_union_type_attributes");
+  SELECT_LEX *sl, *first_sl= first_select();
+  uint item_pos;
+  for (uint pos= 0; pos < first_sl->item_list.elements; pos++)
+  {
+    if (holders[pos].alloc_arguments(thd_arg, count))
+      DBUG_RETURN(true);
+  }
+  for (item_pos= 0, sl= first_sl ;
+       item_pos < count;
+       sl= sl->next_select(), item_pos++)
+  {
+    Item *item_tmp;
+    List_iterator_fast<Item> itx(sl->item_list);
+    for (uint holder_pos= 0 ; (item_tmp= itx++); holder_pos++)
+    {
+      /*
+        If the outer query has a GROUP BY clause, an outer reference to this
+        query block may have been wrapped in a Item_outer_ref, which has not
+        been fixed yet. An Item_type_holder must be created based on a fixed
+        Item, so use the inner Item instead.
+      */
+      DBUG_ASSERT(item_tmp->fixed() ||
+                  (item_tmp->type() == Item::REF_ITEM &&
+                   ((Item_ref *)(item_tmp))->ref_type() ==
+                   Item_ref::OUTER_REF));
+      if (!item_tmp->fixed())
+        item_tmp= item_tmp->real_item();
+      holders[holder_pos].add_argument(item_tmp);
+    }
+  }
+  for (uint pos= 0; pos < first_sl->item_list.elements; pos++)
+  {
+    if (holders[pos].aggregate_attributes(thd_arg))
+      DBUG_RETURN(true);
+  }
+  DBUG_RETURN(false);
+}
+
+
+/**
+  Join data types for the leftmost "count" UNION parts
+  and store corresponding Item_type_holder's into "types".
+*/
+bool st_select_lex_unit::join_union_item_types(THD *thd_arg,
+                                               List<Item> &types,
+                                               uint count)
+{
+  DBUG_ENTER("st_select_lex_unit::join_union_select_list_types");
+  SELECT_LEX *first_sl= first_select();
+  Type_holder *holders;
+
+  if (!(holders= new (thd_arg->mem_root)
+                 Type_holder[first_sl->item_list.elements]) ||
+     join_union_type_handlers(thd_arg, holders, count) ||
+     join_union_type_attributes(thd_arg, holders, count))
+    DBUG_RETURN(true);
+
+  bool is_recursive= with_element && with_element->is_recursive;
+  types.empty();
+  List_iterator_fast<Item> it(first_sl->item_list);
+  Item *item_tmp;
+  for (uint pos= 0; (item_tmp= it++); pos++)
+  {
+    /*
+      SQL standard requires forced nullability only for
+      recursive columns. However type aggregation in our
+      implementation so far does not differentiate between
+      recursive and non-recursive columns of a recursive CTE.
+      TODO: this should be fixed.
+    */
+    bool pos_maybe_null= is_recursive ? true : holders[pos].get_maybe_null();
+
+    /* Error's in 'new' will be detected after loop */
+    types.push_back(new (thd_arg->mem_root)
+                    Item_type_holder(thd_arg,
+                                     item_tmp,
+                                     holders[pos].type_handler(),
+                                     &holders[pos]/*Type_all_attributes*/,
+                                     pos_maybe_null));
+  }
+  if (unlikely(thd_arg->is_fatal_error))
+    DBUG_RETURN(true); // out of memory
+  DBUG_RETURN(false);
+}
+
+
+bool init_item_int(THD* thd, Item_int* &item)
+{
+  if (!item)
+  {
+    Query_arena *arena, backup_arena;
+    arena= thd->activate_stmt_arena_if_needed(&backup_arena);
+
+    item= new (thd->mem_root) Item_int(thd, 0);
+
+    if (arena)
+      thd->restore_active_arena(arena, &backup_arena);
+
+    if (!item)
+    return false;
+  }
+  else
+  {
+    item->value= 0;
+  }
+  return true;
+}
+
+
+bool st_select_lex_unit::prepare(TABLE_LIST *derived_arg,
+                                 select_result *sel_result,
+                                 ulonglong additional_options)
+{
+  SELECT_LEX *lex_select_save= thd->lex->current_select;
+  SELECT_LEX *sl, *first_sl= first_select();
+  bool is_recursive= with_element && with_element->is_recursive;
+  bool is_rec_result_table_created= false;
+  uint union_part_count= 0;
+  select_result *tmp_result;
+  bool is_union_select;
+  bool have_except= false, have_intersect= false,
+    have_except_all_or_intersect_all= false;
+  bool instantiate_tmp_table= false;
+  bool single_tvc= !first_sl->next_select() && first_sl->tvc;
+  bool single_tvc_wo_order= single_tvc && !first_sl->order_list.elements;
+  DBUG_ENTER("st_select_lex_unit::prepare");
+  DBUG_ASSERT(thd == current_thd);
+
+  if (is_recursive && (sl= first_sl->next_select()))
+  {
+    SELECT_LEX *next_sl;
+    for ( ; ; sl= next_sl)
+    {
+      next_sl= sl->next_select();
+      if (!next_sl)
+        break;
+      if (next_sl->with_all_modifier != sl->with_all_modifier)
+      {
+        my_error(ER_NOT_SUPPORTED_YET, MYF(0),
+         "mix of ALL and DISTINCT UNION operations in recursive CTE spec");
+        DBUG_RETURN(TRUE);
+      }
+    }
+  }
+
+  describe= additional_options & SELECT_DESCRIBE;
+
+  /*
+    Save fake_select_lex in case we don't need it for anything but
+    global parameters.
+  */
+  if (saved_fake_select_lex == NULL) // Don't overwrite on PS second prepare
+    saved_fake_select_lex= fake_select_lex;
+
+  /*
+    result object should be reassigned even if preparing already done for
+    max/min subquery (ALL/ANY optimization)
+  */
+  result= sel_result;
+    
+  if (prepared)
+  {
+    if (describe)
+    {
+      /* fast reinit for EXPLAIN */
+      for (sl= first_sl; sl; sl= sl->next_select())
+      {
+	if (sl->tvc)
+	{
+	  sl->tvc->result= result;
+	  if (result->prepare(sl->item_list, this))
+	    DBUG_RETURN(TRUE);
+	  sl->tvc->select_options|= SELECT_DESCRIBE;
+	}
+	else
+	{
+	  sl->join->result= result;
+          lim.clear();
+	  if (!sl->join->procedure &&
+	      result->prepare(sl->join->fields_list, this))
+	  {
+	    DBUG_RETURN(TRUE);
+	  }
+	  sl->join->select_options|= SELECT_DESCRIBE;
+	  sl->join->reinit();
+	}
+      }
+    }
+    DBUG_RETURN(FALSE);
+  }
+  prepared= 1;
+  saved_error= FALSE;
+  
+  thd->lex->current_select= sl= first_sl;
+  found_rows_for_union= first_sl->options & OPTION_FOUND_ROWS;
+  is_union_select= is_unit_op() || fake_select_lex || single_tvc;
+
+  /*
+    If we are reading UNION output and the UNION is in the
+    IN/ANY/ALL/EXISTS subquery, then ORDER BY is redundant and hence should
+    be removed.
+    Example:
+     select ... col IN (select col2 FROM t1 union select col3 from t2 ORDER BY 1)
+
+    (as for ORDER BY ... LIMIT, it currently not supported inside
+     IN/ALL/ANY subqueries)
+    (For non-UNION this removal of ORDER BY clause is done in
+     check_and_do_in_subquery_rewrites())
+  */
+  if (item && is_unit_op() &&
+      (item->is_in_predicate() || item->is_exists_predicate()))
+  {
+    global_parameters()->order_list.first= NULL;
+    global_parameters()->order_list.elements= 0;
+  }
+
+  /* will only optimize once */
+  if (!bag_set_op_optimized && !is_recursive)
+  {
+    optimize_bag_operation(false);
+  }
+
+  for (SELECT_LEX *s= first_sl; s; s= s->next_select())
+  {
+    switch (s->linkage)
+    {
+    case INTERSECT_TYPE:
+      have_intersect= TRUE;
+      if (!s->distinct){
+        have_except_all_or_intersect_all= true;
+      }
+      break;
+    case EXCEPT_TYPE:
+      have_except= TRUE;
+      if (!s->distinct){
+        have_except_all_or_intersect_all= TRUE;
+      }
+      break;
+    default:
+      break;
+    }
+  }
+
+  /* Global option */
+
+  if (is_union_select || is_recursive)
+  {
+    if ((single_tvc_wo_order && !fake_select_lex) ||
+        (is_unit_op() && !union_needs_tmp_table() &&
+	 !have_except && !have_intersect && !single_tvc))
+    {
+      SELECT_LEX *last= first_select();
+      while (last->next_select())
+        last= last->next_select();
+      if (!(tmp_result= union_result=
+              new (thd->mem_root) select_union_direct(thd, sel_result,
+                                                          last)))
+        goto err; /* purecov: inspected */
+      fake_select_lex= NULL;
+      instantiate_tmp_table= false;
+    }
+    else
+    {
+      if (!is_recursive)
+      {
+        /*
+          class "select_unit_ext" handles query contains EXCEPT ALL and / or
+          INTERSECT ALL. Others are handled by class "select_unit"
+          If have EXCEPT ALL or INTERSECT ALL in the query. First operand
+          should be UNION ALL
+        */
+        if (have_except_all_or_intersect_all)
+        {
+          union_result= new (thd->mem_root) select_unit_ext(thd);
+          first_sl->distinct= false;
+        }
+        else
+	  union_result= new (thd->mem_root) select_unit(thd);
+      }
+      else
+      {
+        with_element->rec_result=
+          new (thd->mem_root) select_union_recursive(thd);
+        union_result=  with_element->rec_result;
+        if (fake_select_lex)
+	{
+          if (fake_select_lex->order_list.first ||
+              fake_select_lex->limit_params.explicit_limit)
+          {
+	    my_error(ER_NOT_SUPPORTED_YET, MYF(0),
+                     "global ORDER_BY/LIMIT in recursive CTE spec");
+	    goto err;
+          }
+          fake_select_lex->cleanup();
+          fake_select_lex= NULL;
+        }
+      }
+      if (!(tmp_result= union_result))
+        goto err; /* purecov: inspected */
+      instantiate_tmp_table= true;
+    }
+  }
+  else
+    tmp_result= sel_result;
+
+  sl->context.resolve_in_select_list= TRUE;
+
+  if (!is_union_select && !is_recursive)
+  {
+    if (sl->tvc)
+    {
+      if (sl->tvc->prepare(thd, sl, tmp_result, this))
+	goto err;
+    }
+    else
+    {
+      if (prepare_join(thd, first_sl, tmp_result, additional_options,
+                     is_union_select))
+        goto err;
+
+      if (derived_arg && derived_arg->table &&
+          derived_arg->derived_type == VIEW_ALGORITHM_MERGE &&
+          derived_arg->table->versioned())
+      {
+        /* Got versioning conditions (see vers_setup_conds()), need to update
+           derived_arg. */
+        derived_arg->where= first_sl->where;
+      }
+    }
+    types= first_sl->item_list;
+    goto cont;
+  }
+
+  if (sl->tvc && sl->order_list.elements &&
+      !sl->tvc->to_be_wrapped_as_with_tail())
+  {
+    SELECT_LEX_UNIT *unit= sl->master_unit();
+    if (thd->lex->context_analysis_only & CONTEXT_ANALYSIS_ONLY_VIEW)
+    {
+      unit->fake_select_lex= 0;
+      unit->saved_fake_select_lex= 0;
+    }
+    else
+    {
+      if (!unit->first_select()->next_select())
+      {
+        if (!unit->fake_select_lex)
+        {
+          Query_arena *arena, backup_arena;
+          arena= thd->activate_stmt_arena_if_needed(&backup_arena);
+          bool rc= unit->add_fake_select_lex(thd);
+          if (arena)
+            thd->restore_active_arena(arena, &backup_arena);
+          if (rc)
+            goto err;
+        }
+        SELECT_LEX *fake= unit->fake_select_lex;
+        fake->order_list= sl->order_list;
+        fake->limit_params= sl->limit_params;
+        sl->order_list.empty();
+        sl->limit_params.clear();
+        if (describe)
+          fake->options|= SELECT_DESCRIBE;
+      }
+      else if (!sl->limit_params.explicit_limit)
+        sl->order_list.empty();
+    }
+  }
+
+  for (;sl; sl= sl->next_select(), union_part_count++)
+  {
+    if (sl->tvc)
+    {
+      if (sl->tvc->to_be_wrapped_as_with_tail() &&
+          !(thd->lex->context_analysis_only & CONTEXT_ANALYSIS_ONLY_VIEW))
+
+      {
+        st_select_lex *wrapper_sl= wrap_tvc_with_tail(thd, sl);
+        if (!wrapper_sl)
+          goto err;
+
+        if (sl == first_sl)
+          first_sl= wrapper_sl;
+        sl= wrapper_sl;
+
+        if (prepare_join(thd, sl, tmp_result, additional_options,
+                         is_union_select))
+	  goto err;
+      }
+      else if (sl->tvc->prepare(thd, sl, tmp_result, this))
+	  goto err;
+    }
+    else if (prepare_join(thd, sl, tmp_result, additional_options,
+                          is_union_select))
+      goto err;
+
+    /*
+      setup_tables_done_option should be set only for very first SELECT,
+      because it protect from secont setup_tables call for select-like non
+      select commands (DELETE/INSERT/...) and they use only very first
+      SELECT (for union it can be only INSERT ... SELECT).
+    */
+    additional_options&= ~OPTION_SETUP_TABLES_DONE;
+
+    /*
+      Use items list of underlaid select for derived tables to preserve
+      information about fields lengths and exact types
+    */
+    if (sl == first_sl)
+    {
+      if (with_element)
+      {
+        if (with_element->process_columns_of_derived_unit(thd, this))
+          goto err;
+        if (check_duplicate_names(thd, sl->item_list, 0))
+          goto err;
+      }
+    }
+    else
+    {
+      if (first_sl->item_list.elements != sl->item_list.elements)
+      {
+        my_message(ER_WRONG_NUMBER_OF_COLUMNS_IN_SELECT,
+                   ER_THD(thd, ER_WRONG_NUMBER_OF_COLUMNS_IN_SELECT),
+                   MYF(0));
+        goto err;
+      }
+    }
+    if (is_recursive)
+    {
+      if (!with_element->is_anchor(sl))
+        sl->uncacheable|= UNCACHEABLE_UNITED;
+      if (!is_rec_result_table_created &&
+          (!sl->next_select() ||
+           sl->next_select() == with_element->first_recursive))
+      {
+        ulonglong create_options;
+        create_options= (first_sl->options | thd->variables.option_bits |
+                         TMP_TABLE_ALL_COLUMNS);
+        // Join data types for all non-recursive parts of a recursive UNION
+        if (join_union_item_types(thd, types, union_part_count + 1))
+          goto err;
+        if (union_result->create_result_table(thd, &types,
+                                              MY_TEST(union_distinct),
+                                              create_options,
+                                              &derived_arg->alias, false,
+                                              instantiate_tmp_table, false,
+                                              0))
+          goto err;
+        if (have_except_all_or_intersect_all)
+        {
+          union_result->init();
+        }
+        if (!derived_arg->table)
+        {
+          bool res= false;
+
+          if ((!derived_arg->is_with_table_recursive_reference() ||
+               !derived_arg->derived_result) &&
+              !(derived_arg->derived_result=
+                new (thd->mem_root) select_unit(thd)))
+            goto err; // out of memory
+          thd->create_tmp_table_for_derived= TRUE;
+
+          res= derived_arg->derived_result->create_result_table(thd,
+                                                            &types,
+                                                            FALSE,
+                                                            create_options,
+                                                            &derived_arg->alias,
+                                                            FALSE, FALSE,
+                                                            FALSE, 0);
+          thd->create_tmp_table_for_derived= FALSE;
+          if (res)
+            goto err;
+          derived_arg->derived_result->set_unit(this);
+          derived_arg->table= derived_arg->derived_result->table;
+          if (derived_arg->is_with_table_recursive_reference())
+          {
+            /* Here 'derived_arg' is the primary recursive table reference */
+            derived_arg->with->rec_result->
+              rec_table_refs.push_back(derived_arg);
+          }
+        }
+        with_element->mark_as_with_prepared_anchor();
+        is_rec_result_table_created= true;
+      }
+    }      
+  }
+
+  // In case of a non-recursive UNION, join data types for all UNION parts.
+  if (!is_recursive && join_union_item_types(thd, types, union_part_count))
+    goto err;
+
+cont:
+  /*
+    If the query is using select_union_direct, we have postponed
+    preparation of the underlying select_result until column types
+    are known.
+  */
+  if (union_result != NULL && union_result->postponed_prepare(types))
+    DBUG_RETURN(true);
+
+  if (is_union_select)
+  {
+    /*
+      Check that it was possible to aggregate
+      all collations together for UNION.
+    */
+    List_iterator_fast<Item> tp(types);
+    Item *type;
+    ulonglong create_options;
+    uint save_tablenr= 0;
+    table_map save_map= 0;
+    uint save_maybe_null= 0;
+
+    while ((type= tp++))
+    {
+      /*
+        Test if the aggregated data type is OK for a UNION element.
+        E.g. in case of string data, DERIVATION_NONE is not allowed.
+      */
+      if (type->type() == Item::TYPE_HOLDER && type->type_handler()->
+            union_element_finalize(static_cast<Item_type_holder*>(type)))
+        goto err;
+    }
+    
+    /*
+      Disable the usage of fulltext searches in the last union branch.
+      This is a temporary 5.x limitation because of the way the fulltext
+      search functions are handled by the optimizer.
+      This is manifestation of the more general problems of "taking away"
+      parts of a SELECT statement post-fix_fields(). This is generally not
+      doable since various flags are collected in various places (e.g. 
+      SELECT_LEX) that carry information about the presence of certain 
+      expressions or constructs in the parts of the query.
+      When part of the query is taken away it's not clear how to "divide" 
+      the meaning of these accumulated flags and what to carry over to the
+      recipient query (SELECT_LEX).
+    */
+    if (global_parameters()->ftfunc_list->elements && 
+        global_parameters()->order_list.elements &&
+        global_parameters() != fake_select_lex)
+    {
+      ORDER *ord;
+      Item_func::Functype ft=  Item_func::FT_FUNC;
+      for (ord= global_parameters()->order_list.first; ord; ord= ord->next)
+        if ((*ord->item)->walk (&Item::find_function_processor, FALSE, &ft))
+        {
+          my_error (ER_CANT_USE_OPTION_HERE, MYF(0), "MATCH()");
+          goto err;
+        }
+    }
+
+
+    create_options= (first_sl->options | thd->variables.option_bits |
+                     TMP_TABLE_ALL_COLUMNS);
+    /*
+      Force the temporary table to be a MyISAM table if we're going to use
+      fullext functions (MATCH ... AGAINST .. IN BOOLEAN MODE) when reading
+      from it (this should be removed in 5.2 when fulltext search is moved 
+      out of MyISAM).
+    */
+    if (global_parameters()->ftfunc_list->elements)
+      create_options= create_options | TMP_TABLE_FORCE_MYISAM;
+
+    /* extra field counter */
+    uint hidden= 0;
+    Item_int *addon_fields[2]= {0};
+    if (!is_recursive)
+    {
+      if (have_except_all_or_intersect_all)
+      {
+        /* add duplicate_count */
+        ++hidden;
+      }
+      /* add intersect_count */
+      if (have_intersect)
+        ++hidden;
+
+      for(uint i= 0; i< hidden; i++)
+      {
+        init_item_int(thd, addon_fields[i]);
+        types.push_front(addon_fields[i]);
+        addon_fields[i]->name.str= i ? "__CNT_1" : "__CNT_2";
+        addon_fields[i]->name.length= 7;
+      }
+      bool error=
+        union_result->create_result_table(thd, &types,
+                                          MY_TEST(union_distinct) ||
+                                            have_except_all_or_intersect_all ||
+                                            have_intersect,
+                                          create_options, &empty_clex_str, false,
+                                          instantiate_tmp_table, false,
+                                          hidden);
+      union_result->addon_cnt= hidden;
+      for (uint i= 0; i < hidden; i++)   
+        types.pop();
+      if (unlikely(error))
+        goto err;
+    }
+
+    if (fake_select_lex && !fake_select_lex->first_cond_optimization)
+    {
+      save_tablenr= result_table_list.tablenr_exec;
+      save_map= result_table_list.map_exec;
+      save_maybe_null= result_table_list.maybe_null_exec;
+    }
+    bzero((char*) &result_table_list, sizeof(result_table_list));
+    result_table_list.db.str= (char*) "";
+    result_table_list.db.length= 0;
+    result_table_list.table_name.str= result_table_list.alias.str= "union";
+    result_table_list.table_name.length= result_table_list.alias.length= sizeof("union")-1;
+    result_table_list.table= table= union_result->table;
+    if (fake_select_lex && !fake_select_lex->first_cond_optimization)
+    {
+      result_table_list.tablenr_exec= save_tablenr;
+      result_table_list.map_exec= save_map;
+      result_table_list.maybe_null_exec= save_maybe_null;
+    }
+
+    thd->lex->current_select= lex_select_save;
+    if (!item_list.elements)
+    {
+      Query_arena *arena, backup_arena;
+
+      arena= thd->activate_stmt_arena_if_needed(&backup_arena);
+      
+      saved_error= table->fill_item_list(&item_list);
+      for (uint i= 0; i < hidden; i++)
+        item_list.pop();
+
+      if (arena)
+        thd->restore_active_arena(arena, &backup_arena);
+
+      if (unlikely(saved_error))
+        goto err;
+
+      if (fake_select_lex != NULL &&
+          (thd->stmt_arena->is_stmt_prepare() ||
+           (thd->lex->context_analysis_only & CONTEXT_ANALYSIS_ONLY_VIEW)))
+      {
+        /* Validate the global parameters of this union */
+
+	init_prepare_fake_select_lex(thd, TRUE);
+        /* Should be done only once (the only item_list per statement) */
+        DBUG_ASSERT(fake_select_lex->join == 0);
+	if (!(fake_select_lex->join= new JOIN(thd, item_list, thd->variables.option_bits,
+					      result)))
+	{
+	  fake_select_lex->table_list.empty();
+	  DBUG_RETURN(TRUE);
+	}
+
+        /*
+          Fake st_select_lex should have item list for correct ref_array
+          allocation.
+        */
+	fake_select_lex->item_list= item_list;
+
+	thd->lex->current_select= fake_select_lex;
+
+        /*
+          We need to add up n_sum_items in order to make the correct
+          allocation in setup_ref_array().
+        */
+        fake_select_lex->n_child_sum_items+= global_parameters()->n_sum_items;
+      }
+    }
+    else
+    {
+      /*
+        We're in execution of a prepared statement or stored procedure:
+        reset field items to point at fields from the created temporary table.
+      */
+      table->reset_item_list(&item_list, hidden);
+    }
+    if (fake_select_lex != NULL &&
+        (thd->stmt_arena->is_stmt_prepare() ||
+         (thd->lex->context_analysis_only & CONTEXT_ANALYSIS_ONLY_VIEW)))
+    {
+      if (!fake_select_lex->join &&
+          !(fake_select_lex->join=
+            new JOIN(thd, item_list, thd->variables.option_bits, result)))
+      {
+         fake_select_lex->table_list.empty();
+         DBUG_RETURN(TRUE);
+      }
+      saved_error= fake_select_lex->join->
+        prepare(fake_select_lex->table_list.first, 0,
+                global_parameters()->order_list.elements, // og_num
+                global_parameters()->order_list.first,    // order
+                false, NULL, NULL, NULL, fake_select_lex, this);
+      fake_select_lex->table_list.empty();
+    }
+  }
+
+  thd->lex->current_select= lex_select_save;
+
+  DBUG_RETURN(saved_error || thd->is_fatal_error);
+
+err:
+  thd->lex->current_select= lex_select_save;
+  (void) cleanup();
+  DBUG_RETURN(TRUE);
+}
+
+
+/**
+  @brief
+    Optimize a sequence of set operations
+
+  @param first_sl first select of the level now under processing
+
+  @details
+    The method optimizes with the following rules:
+    - (1)If a subsequence of INTERSECT contains at least one INTERSECT DISTINCT
+        or this subsequence is followed by UNION/EXCEPT DISTINCT then all
+        elements in the subsequence can changed for INTERSECT DISTINCT
+    - (2)If previous set operation is DISTINCT then EXCEPT ALL can be replaced
+        for EXCEPT DISTINCT
+    - (3)If UNION DISTINCT / EXCEPT DISTINCT follows a subsequence of UNION ALL
+        then all set operations of this subsequence can be replaced for
+        UNION DISTINCT
+
+    For derived table it will look up outer select, and do optimize based on
+    outer select.
+
+    Variable "union_distinct" will be updated in the end.
+    Not compatible with Oracle Mode.
+*/
+
+void st_select_lex_unit::optimize_bag_operation(bool is_outer_distinct)
+{
+  /*
+    skip run optimize for:
+      ORACLE MODE
+      CREATE VIEW
+      PREPARE ... FROM
+      recursive
+  */
+  if ((thd->variables.sql_mode & MODE_ORACLE) ||
+    (thd->lex->context_analysis_only & CONTEXT_ANALYSIS_ONLY_VIEW) ||
+    (fake_select_lex != NULL && thd->stmt_arena->is_stmt_prepare()) ||
+    (with_element && with_element->is_recursive ))
+    return;
+  DBUG_ASSERT(!bag_set_op_optimized);
+
+  SELECT_LEX *sl;
+  /* INTERSECT subsequence can occur only at the very beginning */
+  /* The first select with linkage == INTERSECT_TYPE */
+  SELECT_LEX *intersect_start= NULL;
+  /* The first select after the INTERSECT subsequence */
+  SELECT_LEX *intersect_end= NULL;
+  /*
+    Will point to the last node before UNION ALL subsequence.
+    Index can be disable there.
+  */
+  SELECT_LEX *disable_index= NULL;
+  /*
+    True if there is a select with:
+    linkage == INTERSECT_TYPE && distinct==true
+  */
+  bool any_intersect_distinct= false;
+  SELECT_LEX *prev_sl= first_select();
+
+  /* process INTERSECT subsequence in the begining */
+  for (sl= prev_sl->next_select(); sl; prev_sl= sl, sl= sl->next_select())
+  {
+    if (sl->linkage != INTERSECT_TYPE)
+    {
+      intersect_end= sl;
+      break;
+    }
+    else
+    {
+      if (!intersect_start)
+        intersect_start= sl;
+      if (sl->distinct)
+      {
+        any_intersect_distinct= true;
+        disable_index= sl;
+      }
+    }
+  }
+
+  /* if subquery only contains INTERSECT and outer is UNION DISTINCT*/
+  if (!sl && is_outer_distinct)
+    any_intersect_distinct= true;
+
+  /* The first select of the current UNION ALL subsequence */
+  SELECT_LEX *union_all_start= NULL;
+  for ( ; sl; prev_sl= sl, sl= sl->next_select())
+  {
+    DBUG_ASSERT (sl->linkage != INTERSECT_TYPE);
+    if (!sl->distinct)
+    {
+      if (sl->linkage == UNION_TYPE)
+      {
+        if (!union_all_start)
+        {
+          union_all_start= sl;
+        }
+      }
+      else
+      {
+        DBUG_ASSERT (sl->linkage == EXCEPT_TYPE);
+        union_all_start= NULL;
+        if (prev_sl->distinct && prev_sl->is_set_op())
+        {
+          sl->distinct= true;
+          disable_index= sl;
+        }
+      }
+    }
+    else
+    { /* sl->distinct == true */
+      for (SELECT_LEX *si= union_all_start; si && si != sl; si= si->next_select())
+      {
+          si->distinct= true;
+      }
+      union_all_start= NULL;
+      disable_index= sl;
+    }
+  }
+
+  if (is_outer_distinct)
+  {
+    for (SELECT_LEX *si= union_all_start; si && si != sl; si= si->next_select())
+    {
+        si->distinct= true;
+    }
+    union_all_start= NULL;
+  }
+
+  if (any_intersect_distinct ||
+      (intersect_end != NULL && intersect_end->distinct))
+  {
+    for (sl= intersect_start; sl && sl != intersect_end; sl= sl->next_select())
+    {
+      sl->distinct= true;
+      if (disable_index && disable_index->linkage == INTERSECT_TYPE)
+        disable_index= sl;
+    }
+  }
+  /*
+    if disable_index points to a INTERSECT, based on rule 1 we can set it
+    to the last INTERSECT node.
+  */
+  if (disable_index && disable_index->linkage == INTERSECT_TYPE &&
+    intersect_end && intersect_end->distinct)
+    disable_index= intersect_end;
+  /* union_distinct controls when to disable index */
+  union_distinct= disable_index;
+
+  /* recursive call this function for whole lex tree */
+  for(sl= first_select(); sl; sl= sl->next_select())
+  {
+    if (sl->is_unit_nest() &&
+        sl->first_inner_unit() &&
+        !sl->first_inner_unit()->bag_set_op_optimized)
+      sl->first_inner_unit()->optimize_bag_operation(sl->distinct);
+  }
+
+  /* mark as optimized */
+  bag_set_op_optimized= true;
+}
+
+
+/**
+  Run optimization phase.
+
+  @return false unit successfully passed optimization phase.
+  @return TRUE an error occur.
+*/
+bool st_select_lex_unit::optimize()
+{
+  SELECT_LEX *lex_select_save= thd->lex->current_select;
+  SELECT_LEX *select_cursor=first_select();
+  DBUG_ENTER("st_select_lex_unit::optimize");
+
+  if (optimized && !uncacheable && !describe)
+    DBUG_RETURN(false);
+
+  if (with_element && with_element->is_recursive && optimize_started)
+    DBUG_RETURN(false);
+  optimize_started= true;
+
+  if (uncacheable || !item || !item->assigned() || describe)
+  {
+    if (item)
+      item->reset_value_registration();
+    if (optimized && item)
+    {
+      if (item->assigned())
+      {
+        item->assigned(0); // We will reinit & rexecute unit
+        item->reset();
+      }
+      if (table->is_created())
+      {
+        table->file->ha_delete_all_rows();
+        table->file->info(HA_STATUS_VARIABLE);
+      }
+      /* re-enabling indexes for next subselect iteration */
+      if ((union_result->force_enable_index_if_needed() || union_distinct))
+      {
+        if(table->file->ha_enable_indexes(HA_KEY_SWITCH_ALL))
+          DBUG_ASSERT(0);
+        else
+          table->no_keyread= 0;
+      }
+    }
+    for (SELECT_LEX *sl= select_cursor; sl; sl= sl->next_select())
+    {
+      if (sl->tvc)
+      {
+	sl->tvc->select_options=
+          (lim.is_unlimited() || sl->braces) ?
+          sl->options & ~OPTION_FOUND_ROWS : sl->options | found_rows_for_union;
+	if (sl->tvc->optimize(thd))
+        {
+          thd->lex->current_select= lex_select_save;
+          DBUG_RETURN(TRUE);
+        }
+        if (derived)
+	  sl->increase_derived_records(sl->tvc->get_records());
+	continue;
+      }
+      thd->lex->current_select= sl;
+
+      if (optimized)
+	saved_error= sl->join->reinit();
+      else
+      {
+        set_limit(sl);
+	if (sl == global_parameters() || describe)
+	{
+          lim.remove_offset();
+	  /*
+	    We can't use LIMIT at this stage if we are using ORDER BY for the
+	    whole query
+	  */
+	  if (sl->order_list.first || describe)
+            lim.set_unlimited();
+        }
+
+        /*
+          When using braces, SQL_CALC_FOUND_ROWS affects the whole query:
+          we don't calculate found_rows() per union part.
+          Otherwise, SQL_CALC_FOUND_ROWS should be done on all sub parts.
+        */
+        sl->join->select_options=
+          (lim.is_unlimited() || sl->braces) ?
+          sl->options & ~OPTION_FOUND_ROWS : sl->options | found_rows_for_union;
+
+	saved_error= sl->join->optimize();
+      }
+
+      if (unlikely(saved_error))
+      {
+	thd->lex->current_select= lex_select_save;
+	DBUG_RETURN(saved_error);
+      }
+    }
+  }
+  optimized= 1;
+
+  thd->lex->current_select= lex_select_save;
+  DBUG_RETURN(saved_error);
+}
+
+
+bool st_select_lex_unit::exec()
+{
+  SELECT_LEX *lex_select_save= thd->lex->current_select;
+  SELECT_LEX *select_cursor=first_select();
+  ulonglong add_rows=0;
+  ha_rows examined_rows= 0;
+  bool first_execution= !executed;
+  DBUG_ENTER("st_select_lex_unit::exec");
+  bool was_executed= executed;
+
+  if (executed && !uncacheable && !describe)
+    DBUG_RETURN(FALSE);
+  executed= 1;
+  if (!(uncacheable & ~UNCACHEABLE_EXPLAIN) && item &&
+      !item->with_recursive_reference)
+    item->make_const();
+  
+  saved_error= optimize();
+  
+  create_explain_query_if_not_exists(thd->lex, thd->mem_root);
+
+  if (!saved_error && !was_executed)
+    save_union_explain(thd->lex->explain);
+
+  if (unlikely(saved_error))
+    DBUG_RETURN(saved_error);
+
+  if (union_result)
+  {
+    union_result->init();
+    if (uncacheable & UNCACHEABLE_DEPENDENT &&
+        union_result->table && union_result->table->is_created())
+    {
+      union_result->table->file->ha_delete_all_rows();
+      union_result->table->file->ha_enable_indexes(HA_KEY_SWITCH_ALL);
+    }
+  }
+
+  if (uncacheable || !item || !item->assigned() || describe)
+  {
+    if (!fake_select_lex && !(with_element && with_element->is_recursive))
+      union_result->cleanup();
+    for (SELECT_LEX *sl= select_cursor; sl; sl= sl->next_select())
+    {
+      ha_rows records_at_start= 0;
+      thd->lex->current_select= sl;
+      if (union_result)
+        union_result->change_select();
+      if (fake_select_lex)
+      {
+        if (sl != thd->lex->first_select_lex())
+          fake_select_lex->uncacheable|= sl->uncacheable;
+        else
+          fake_select_lex->uncacheable= 0;
+      }
+
+      {
+        set_limit(sl);
+	if (sl == global_parameters() || describe)
+	{
+	  lim.remove_offset();
+	  /*
+	    We can't use LIMIT at this stage if we are using ORDER BY for the
+	    whole query
+	  */
+	  if (sl->order_list.first || describe)
+	    lim.set_unlimited();
+        }
+
+        /*
+          When using braces, SQL_CALC_FOUND_ROWS affects the whole query:
+          we don't calculate found_rows() per union part.
+          Otherwise, SQL_CALC_FOUND_ROWS should be done on all sub parts.
+        */
+	if (sl->tvc)
+	{
+	  sl->tvc->select_options=
+             (lim.is_unlimited() || sl->braces) ?
+             sl->options & ~OPTION_FOUND_ROWS : sl->options | found_rows_for_union;
+	  saved_error= sl->tvc->optimize(thd);
+	}
+	else
+	{
+          sl->join->select_options=
+            (lim.is_unlimited() || sl->braces) ?
+            sl->options & ~OPTION_FOUND_ROWS : sl->options | found_rows_for_union;
+	  saved_error= sl->join->optimize();
+	}
+      }
+      if (likely(!saved_error))
+      {
+	records_at_start= table->file->stats.records;
+	if (sl->tvc)
+	  sl->tvc->exec(sl);
+	else
+	  sl->join->exec();
+        if (sl == union_distinct && !have_except_all_or_intersect_all &&
+            !(with_element && with_element->is_recursive))
+	{
+          // This is UNION DISTINCT, so there should be a fake_select_lex
+          DBUG_ASSERT(fake_select_lex != NULL);
+	  if (unlikely(table->file->ha_disable_indexes(HA_KEY_SWITCH_ALL)))
+	    DBUG_RETURN(TRUE);
+	  table->no_keyread=1;
+	}
+	if (!sl->tvc)
+	  saved_error= sl->join->error;
+	if (likely(!saved_error))
+	{
+	  examined_rows+= thd->get_examined_row_count();
+          thd->set_examined_row_count(0);
+	  if (union_result->flush())
+	  {
+	    thd->lex->current_select= lex_select_save;
+	    DBUG_RETURN(1);
+	  }
+	}
+      }
+      if (unlikely(saved_error))
+      {
+	thd->lex->current_select= lex_select_save;
+	DBUG_RETURN(saved_error);
+      }
+      if (fake_select_lex != NULL)
+      {
+        /* Needed for the following test and for records_at_start in next loop */
+        int error= table->file->info(HA_STATUS_VARIABLE);
+        if (unlikely(error))
+        {
+          table->file->print_error(error, MYF(0));
+          DBUG_RETURN(1);
+        }
+      }
+      if (found_rows_for_union && !sl->braces &&
+          !lim.is_unlimited())
+      {
+	/*
+	  This is a union without braces. Remember the number of rows that
+	  could also have been part of the result set.
+	  We get this from the difference of between total number of possible
+	  rows and actual rows added to the temporary table.
+	*/
+	add_rows+= (ulonglong) (thd->limit_found_rows - (ulonglong)
+			      ((table->file->stats.records -  records_at_start)));
+      }
+      if (thd->killed == ABORT_QUERY)
+      {
+        /*
+          Stop execution of the remaining queries in the UNIONS, and produce
+          the current result.
+        */
+        push_warning_printf(thd, Sql_condition::WARN_LEVEL_WARN,
+                            ER_QUERY_RESULT_INCOMPLETE,
+                            ER_THD(thd, ER_QUERY_RESULT_INCOMPLETE),
+                            "LIMIT ROWS EXAMINED",
+                            thd->lex->limit_rows_examined->val_uint());
+        thd->reset_killed();
+        break;
+      }
+    }
+  }
+
+  DBUG_EXECUTE_IF("show_explain_probe_union_read", 
+                   dbug_serve_apcs(thd, 1););
+  {
+    List<Item_func_match> empty_list;
+    empty_list.empty();
+    /*
+      Disable LIMIT ROWS EXAMINED in order to produce the possibly incomplete
+      result of the UNION without interruption due to exceeding the limit.
+    */
+    thd->lex->limit_rows_examined_cnt= ULONGLONG_MAX;
+
+    // Check if EOM
+    if (fake_select_lex != NULL && likely(!thd->is_fatal_error))
+    {
+       /* Send result to 'result' */
+       saved_error= true;
+
+      set_limit(global_parameters());
+      init_prepare_fake_select_lex(thd, first_execution);
+      JOIN *join= fake_select_lex->join;
+      saved_error= false;
+      if (!join)
+      {
+	/*
+	  allocate JOIN for fake select only once (prevent
+	  mysql_select automatic allocation)
+          TODO: The above is nonsense. mysql_select() will not allocate the
+          join if one already exists. There must be some other reason why we
+          don't let it allocate the join. Perhaps this is because we need
+          some special parameter values passed to join constructor?
+	*/
+	if (unlikely(!(fake_select_lex->join=
+                       new JOIN(thd, item_list, fake_select_lex->options,
+                                result))))
+	{
+	  fake_select_lex->table_list.empty();
+	  goto err;
+	}
+        fake_select_lex->join->no_const_tables= TRUE;
+
+        /*
+          Fake st_select_lex should have item list for correct ref_array
+          allocation.
+        */
+        fake_select_lex->item_list= item_list;
+
+        /*
+          We need to add up n_sum_items in order to make the correct
+          allocation in setup_ref_array().
+          Don't add more sum_items if we have already done JOIN::prepare
+          for this (with a different join object)
+        */
+        if (fake_select_lex->ref_pointer_array.is_null())
+          fake_select_lex->n_child_sum_items+= global_parameters()->n_sum_items;
+        
+        if (!was_executed)
+          save_union_explain_part2(thd->lex->explain);
+
+        saved_error= mysql_select(thd, &result_table_list,
+                                  item_list, NULL,
+				  global_parameters()->order_list.elements,
+				  global_parameters()->order_list.first,
+                                  NULL, NULL, NULL,
+                                  fake_select_lex->options | SELECT_NO_UNLOCK,
+                                  result, this, fake_select_lex);
+      }
+      else
+      {
+        if (describe)
+        {
+          /*
+            In EXPLAIN command, constant subqueries that do not use any
+            tables are executed two times:
+             - 1st time is a real evaluation to get the subquery value
+             - 2nd time is to produce EXPLAIN output rows.
+            1st execution sets certain members (e.g. select_result) to perform
+            subquery execution rather than EXPLAIN line production. In order 
+            to reset them back, we re-do all of the actions (yes it is ugly):
+          */ // psergey-todo: is the above really necessary anymore?? 
+	  join->init(thd, item_list, fake_select_lex->options, result);
+          saved_error= mysql_select(thd, &result_table_list, item_list, NULL,
+				    global_parameters()->order_list.elements,
+				    global_parameters()->order_list.first,
+                                    NULL, NULL, NULL,
+                                    fake_select_lex->options | SELECT_NO_UNLOCK,
+                                    result, this, fake_select_lex);
+        }
+        else
+        {
+          join->join_examined_rows= 0;
+          saved_error= join->reinit();
+          join->exec();
+        }
+      }
+
+      fake_select_lex->table_list.empty();
+      if (likely(!saved_error))
+      {
+	thd->limit_found_rows = (ulonglong)table->file->stats.records + add_rows;
+        thd->inc_examined_row_count(examined_rows);
+      }
+      /*
+	Mark for slow query log if any of the union parts didn't use
+	indexes efficiently
+      */
+    }
+  }
+  thd->lex->current_select= lex_select_save;
+err:
+  thd->lex->set_limit_rows_examined();
+  DBUG_RETURN(saved_error);
+}
+
+
+/**
+  @brief
+    Execute the union of the specification of a recursive with table 
+
+  @details
+    The method is performed only for the units that are specifications
+    if recursive with table T. If the specification contains an anchor
+    part then the first call of this method executes only this part
+    while the following calls execute the recursive part. If there are
+    no anchors each call executes the whole unit.
+    Before the excution the method cleans up the temporary table 
+    to where the new rows of the recursive table are sent.
+    After the execution the unit these rows are copied to the 
+    temporary tables created for recursive references of T. 
+    If the specification if T is restricted (standards compliant)
+    then these temporary tables are cleaned up before new rows
+    are copied into them.  
+
+  @retval
+    false   on success
+    true    on failure
+*/
+
+bool st_select_lex_unit::exec_recursive()
+{
+  st_select_lex *lex_select_save= thd->lex->current_select;
+  st_select_lex *start= with_element->first_recursive;
+  TABLE *incr_table= with_element->rec_result->incr_table;
+  st_select_lex *end= NULL;
+  bool is_unrestricted= with_element->is_unrestricted();
+  List_iterator_fast<TABLE_LIST> li(with_element->rec_result->rec_table_refs);
+  TMP_TABLE_PARAM *tmp_table_param= &with_element->rec_result->tmp_table_param;
+  ha_rows examined_rows= 0;
+  bool was_executed= executed;
+  TABLE_LIST *rec_tbl;
+
+  DBUG_ENTER("st_select_lex_unit::exec_recursive");
+
+  executed= 1;
+  create_explain_query_if_not_exists(thd->lex, thd->mem_root);
+  if (!was_executed)
+    save_union_explain(thd->lex->explain);
+
+  if (with_element->level == 0)
+  {
+    if (!incr_table->is_created() &&
+        instantiate_tmp_table(incr_table,
+                              tmp_table_param->keyinfo,
+                              tmp_table_param->start_recinfo,
+                              &tmp_table_param->recinfo,
+                              0))
+      DBUG_RETURN(1);
+    incr_table->file->extra(HA_EXTRA_WRITE_CACHE);
+    incr_table->file->extra(HA_EXTRA_IGNORE_DUP_KEY);
+    start= first_select();
+    if (with_element->with_anchor)
+      end= with_element->first_recursive;
+  }
+  else if (unlikely((saved_error= incr_table->file->ha_delete_all_rows())))
+    goto err;
+
+  for (st_select_lex *sl= start ; sl != end; sl= sl->next_select())
+  {
+    if (with_element->level)
+    {
+      for (TABLE_LIST *derived= with_element->derived_with_rec_ref.first;
+           derived;
+           derived= derived->next_with_rec_ref)
+      {
+        if (derived->is_materialized_derived())
+	{
+          if (derived->table->is_created())
+            derived->table->file->ha_delete_all_rows();
+          derived->table->reginfo.join_tab->preread_init_done= false;
+        }
+      }
+    }
+    thd->lex->current_select= sl;
+    set_limit(sl);
+    if (sl->tvc)
+      sl->tvc->exec(sl);
+    else
+    {
+      sl->join->exec();
+      saved_error= sl->join->error;
+    }
+    if (likely(!saved_error))
+    {
+       examined_rows+= thd->get_examined_row_count();
+       thd->set_examined_row_count(0);
+       if (unlikely(union_result->flush()))
+       {
+	 thd->lex->current_select= lex_select_save;
+	 DBUG_RETURN(1);
+       }
+    }
+    if (unlikely(saved_error))
+    {
+      thd->lex->current_select= lex_select_save;
+      goto err;
+      
+    }
+  }
+
+  thd->inc_examined_row_count(examined_rows);
+
+  incr_table->file->info(HA_STATUS_VARIABLE);
+  if (with_element->level && incr_table->file->stats.records == 0)
+    with_element->set_as_stabilized();
+  else
+    with_element->level++;
+
+  while ((rec_tbl= li++))
+  {
+    TABLE *rec_table= rec_tbl->table;
+    saved_error=
+      incr_table->insert_all_rows_into_tmp_table(thd, rec_table,
+                                                 tmp_table_param,
+                                                 !is_unrestricted);
+    if (!with_element->rec_result->first_rec_table_to_update)
+      with_element->rec_result->first_rec_table_to_update= rec_table;
+    if (with_element->level == 1 && rec_table->reginfo.join_tab)
+      rec_table->reginfo.join_tab->preread_init_done= true;
+  }
+  for (Item_subselect *sq= with_element->sq_with_rec_ref.first;
+       sq;
+       sq= sq->next_with_rec_ref)
+  {
+    sq->reset();
+    sq->engine->force_reexecution();
+  }   
+
+  thd->lex->current_select= lex_select_save;
+err:
+  thd->lex->set_limit_rows_examined();
+  DBUG_RETURN(saved_error);    
+}
+
+
+bool st_select_lex_unit::cleanup()
+{
+  bool error= 0;
+  DBUG_ENTER("st_select_lex_unit::cleanup");
+
+  if (cleaned)
+  {
+    DBUG_RETURN(FALSE);
+  }
+  if (with_element && with_element->is_recursive && union_result &&
+      with_element->rec_outer_references)
+  {
+    select_union_recursive *result= with_element->rec_result;
+    if (++result->cleanup_count == with_element->rec_outer_references)
+    {
+      /*
+        Perform cleanup for with_element and for all with elements
+        mutually recursive with it.
+      */
+      cleaned= 1;
+      with_element->get_next_mutually_recursive()->spec->cleanup();
+    }
+    else
+    {
+      /*
+        Just increment by 1 cleanup_count for with_element and
+        for all with elements mutually recursive with it.
+      */
+      With_element *with_elem= with_element;
+      while ((with_elem= with_elem->get_next_mutually_recursive()) !=
+             with_element)
+        with_elem->rec_result->cleanup_count++;
+      DBUG_RETURN(FALSE);
+    }
+  }
+  columns_are_renamed= false;
+  cleaned= 1;
+
+  for (SELECT_LEX *sl= first_select(); sl; sl= sl->next_select())
+    error|= sl->cleanup();
+     
+  if (fake_select_lex)
+  {
+    error|= fake_select_lex->cleanup();
+    /*
+      There are two cases when we should clean order items:
+      1. UNION with SELECTs which all enclosed into braces
+        in this case global_parameters == fake_select_lex
+      2. UNION where last SELECT is not enclosed into braces
+        in this case global_parameters == 'last select'
+      So we should use global_parameters->order_list for
+      proper order list clean up.
+      Note: global_parameters and fake_select_lex are always
+            initialized for UNION
+    */
+    DBUG_ASSERT(global_parameters());
+    if (global_parameters()->order_list.elements)
+    {
+      ORDER *ord;
+      for (ord= global_parameters()->order_list.first; ord; ord= ord->next)
+        (*ord->item)->walk (&Item::cleanup_processor, 0, 0);
+    }
+  }
+
+  if (with_element && with_element->is_recursive)
+  {
+    if (union_result)
+    {
+      ((select_union_recursive *) union_result)->cleanup();
+      delete union_result;
+      union_result= 0;
+    }
+    with_element->mark_as_cleaned();
+  }
+  else
+  {
+    if (union_result)
+    {
+      delete union_result;
+      union_result=0; // Safety
+      if (table)
+        free_tmp_table(thd, table);
+      table= 0; // Safety
+    }
+  }
+
+  DBUG_RETURN(error);
+}
+
+
+void st_select_lex_unit::reinit_exec_mechanism()
+{
+  prepared= optimized= optimized_2= executed= 0;
+  optimize_started= 0;
+  if (with_element && with_element->is_recursive)
+    with_element->reset_recursive_for_exec();
+}
+
+
+/**
+  Change the select_result object used to return the final result of
+  the unit, replacing occurences of old_result with new_result.
+
+  @param new_result New select_result object
+  @param old_result Old select_result object
+
+  @retval false Success
+  @retval true  Error
+*/
+
+bool st_select_lex_unit::change_result(select_result_interceptor *new_result,
+                                       select_result_interceptor *old_result)
+{
+  for (SELECT_LEX *sl= first_select(); sl; sl= sl->next_select())
+  {
+    if (sl->join)
+      if (sl->join->change_result(new_result, old_result))
+	return true; /* purecov: inspected */
+  }
+  /*
+    If there were a fake_select_lex->join, we would have to change the
+    result of that also, but change_result() is called before such an
+    object is created.
+  */
+  DBUG_ASSERT(fake_select_lex == NULL || fake_select_lex->join == NULL);
+  return false;
+}
+
+/*
+  Get column type information for this unit.
+
+  SYNOPSIS
+    st_select_lex_unit::get_column_types()
+      @param for_cursor if true return the list the fields
+                        retrieved by the cursor
+
+  DESCRIPTION
+    For a single-select the column types are taken
+    from the list of selected items. For a union this function
+    assumes that st_select_lex_unit::prepare has been called
+    and returns the type holders that were created for unioned
+    column types of all selects.
+
+  NOTES
+    The implementation of this function should be in sync with
+    st_select_lex_unit::prepare()
+*/
+
+List<Item> *st_select_lex_unit::get_column_types(bool for_cursor)
+{
+  SELECT_LEX *sl= first_select();
+  bool is_procedure= !sl->tvc && sl->join->procedure ;
+
+  if (is_procedure)
+  {
+    /* Types for "SELECT * FROM t1 procedure analyse()"
+       are generated during execute */
+    return &sl->join->procedure_fields_list;
+  }
+
+
+  if (is_unit_op())
+  {
+    DBUG_ASSERT(prepared);
+    /* Types are generated during prepare */
+    return &types;
+  }
+
+  return for_cursor ? sl->join->fields :  &sl->item_list;
+}
+
+
+static void cleanup_order(ORDER *order)
+{
+  for (; order; order= order->next)
+    order->counter_used= 0;
+}
+
+
+static void cleanup_window_funcs(List<Item_window_func> &win_funcs)
+{
+  List_iterator_fast<Item_window_func> it(win_funcs);
+  Item_window_func *win_func;
+  while ((win_func= it++))
+  {
+    Window_spec *win_spec= win_func->window_spec;
+    if (!win_spec)
+      continue;
+    if (win_spec->save_partition_list)
+    {
+      win_spec->partition_list= win_spec->save_partition_list;
+      win_spec->save_partition_list= NULL;
+    }
+    if (win_spec->save_order_list)
+    {
+      win_spec->order_list= win_spec->save_order_list;
+      win_spec->save_order_list= NULL;
+    }
+  }
+}
+
+
+bool st_select_lex::cleanup()
+{
+  bool error= FALSE;
+  DBUG_ENTER("st_select_lex::cleanup()");
+
+  DBUG_PRINT("info", ("select: %p (%u)  JOIN %p",
+                      this, select_number, join));
+  cleanup_order(order_list.first);
+  cleanup_order(group_list.first);
+  cleanup_ftfuncs(this);
+
+  cleanup_window_funcs(window_funcs);
+
+  if (join)
+  {
+    List_iterator<TABLE_LIST> ti(leaf_tables);
+    TABLE_LIST *tbl;
+    while ((tbl= ti++))
+    {
+      if (tbl->is_recursive_with_table() &&
+          !tbl->is_with_table_recursive_reference())
+      {
+        /*
+          If query is killed before open_and_process_table() for tbl
+          is called then 'with' is already set, but 'derived' is not.
+        */
+        st_select_lex_unit *unit= tbl->with->spec;
+        error|= (bool) error | (uint) unit->cleanup();
+      }
+    }
+    DBUG_ASSERT((st_select_lex*)join->select_lex == this);
+    error= join->destroy();
+    delete join;
+    join= 0;
+  }
+  leaf_tables.empty();
+  for (SELECT_LEX_UNIT *lex_unit= first_inner_unit(); lex_unit ;
+       lex_unit= lex_unit->next_unit())
+  {
+    if (lex_unit->with_element && lex_unit->with_element->is_recursive &&
+        lex_unit->with_element->rec_outer_references)
+      continue;
+    error= (bool) ((uint) error | (uint) lex_unit->cleanup());
+  }
+  inner_refs_list.empty();
+  exclude_from_table_unique_test= FALSE;
+  hidden_bit_fields= 0;
+  DBUG_RETURN(error);
+}
+
+
+void st_select_lex::cleanup_all_joins(bool full)
+{
+  SELECT_LEX_UNIT *unit;
+  SELECT_LEX *sl;
+  DBUG_ENTER("st_select_lex::cleanup_all_joins");
+
+  if (join)
+    join->cleanup(full);
+
+  for (unit= first_inner_unit(); unit; unit= unit->next_unit())
+  {
+    if (unit->with_element && unit->with_element->is_recursive)
+      continue;
+    for (sl= unit->first_select(); sl; sl= sl->next_select())
+      sl->cleanup_all_joins(full);
+  }
+  DBUG_VOID_RETURN;
+}
+
+
+/**
+  Set exclude_from_table_unique_test for selects of this unit and all
+  underlying selects.
+
+  @note used to exclude materialized derived tables (views) from unique
+  table check.
+*/
+
+void st_select_lex_unit::set_unique_exclude()
+{
+  for (SELECT_LEX *sl= first_select(); sl; sl= sl->next_select())
+  {
+    sl->exclude_from_table_unique_test= TRUE;
+    for (SELECT_LEX_UNIT *unit= sl->first_inner_unit();
+         unit;
+         unit= unit->next_unit())
+    {
+      unit->set_unique_exclude();
+    }
+  }
+}
+
+/**
+  @brief
+  Check if the derived table is guaranteed to have distinct rows because of
+  UNION operations used to populate it.
+
+  @detail
+    UNION operation removes duplicate rows from its output. That is, a query like
+
+      select * from t1 UNION select * from t2
+
+    will not produce duplicate rows in its output, even if table t1 (and/or t2)
+    contain duplicate rows. EXCEPT and INTERSECT operations also have this
+    property.
+
+    On the other hand, UNION ALL operation doesn't remove duplicates. (The SQL
+    standard also defines EXCEPT ALL and INTERSECT ALL, but we don't support
+    them).
+
+    st_select_lex_unit computes its value left to right. That is, if there is
+     a st_select_lex_unit object describing
+
+      (select #1) OP1 (select #2) OP2 (select #3)
+
+    then ((select #1) OP1 (select #2)) is computed first, and OP2 is computed
+    second.
+
+    How can one tell if st_select_lex_unit is guaranteed to have distinct
+    output rows? This depends on whether the last operation was duplicate-
+    removing or not:
+    - UNION ALL is not duplicate-removing
+    - all other operations are duplicate-removing
+*/
+
+bool st_select_lex_unit::check_distinct_in_union()
+{
+  if (union_distinct && !union_distinct->next_select())
+    return true;
+  return false;
+}