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, 7946 insertions, 0 deletions

diff --git a/sql/item_cmpfunc.cc b/sql/item_cmpfunc.cc
new file mode 100644
index 00000000..bfe03e1c
--- /dev/null
+++ b/sql/item_cmpfunc.cc
@@ -0,0 +1,7946 @@
+/* Copyright (c) 2000, 2013, Oracle and/or its affiliates.
+   Copyright (c) 2009, 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 */
+
+
+/**
+  @file
+
+  @brief
+  This file defines all compare functions
+*/
+
+#ifdef USE_PRAGMA_IMPLEMENTATION
+#pragma implementation				// gcc: Class implementation
+#endif
+
+#include "mariadb.h"
+#include "sql_priv.h"
+#include <m_ctype.h>
+#include "sql_select.h"
+#include "sql_parse.h"                          // check_stack_overrun
+#include "sql_base.h"                  // dynamic_column_error_message
+
+#define PCRE2_STATIC 1             /* Important on Windows */
+#include "pcre2.h"                 /* pcre2 header file */
+#include "my_json_writer.h"
+
+/*
+  Compare row signature of two expressions
+
+  SYNOPSIS:
+    cmp_row_type()
+    item1          the first expression
+    item2         the second expression
+
+  DESCRIPTION
+    The function checks that two expressions have compatible row signatures
+    i.e. that the number of columns they return are the same and that if they
+    are both row expressions then each component from the first expression has 
+    a row signature compatible with the signature of the corresponding component
+    of the second expression.
+
+  RETURN VALUES
+    1  type incompatibility has been detected
+    0  otherwise
+*/
+
+static int cmp_row_type(Item* item1, Item* item2)
+{
+  uint n= item1->cols();
+  if (item2->check_cols(n))
+    return 1;
+  for (uint i=0; i<n; i++)
+  {
+    if (item2->element_index(i)->check_cols(item1->element_index(i)->cols()) ||
+        (item1->element_index(i)->result_type() == ROW_RESULT &&
+         cmp_row_type(item1->element_index(i), item2->element_index(i))))
+      return 1;
+  }
+  return 0;
+}
+
+
+/**
+  Aggregates result types from the array of items.
+
+  This method aggregates comparison handler from the array of items.
+  The result handler is used later for comparison of values of these items.
+
+  aggregate_for_comparison()
+  funcname                      the function or operator name,
+                                for error reporting
+  items                         array of items to aggregate the type from
+  nitems                        number of items in the array
+  int_uint_as_dec               what to do when comparing INT to UINT:
+                                set the comparison handler to decimal or int.
+
+  @retval true  type incompatibility has been detected
+  @retval false otherwise
+*/
+
+bool Type_handler_hybrid_field_type::
+aggregate_for_comparison(const LEX_CSTRING &funcname,
+                         Item **items,
+                         uint nitems,
+                         bool int_uint_as_dec)
+{
+  uint unsigned_count= items[0]->unsigned_flag;
+  /*
+    Convert sub-type to super-type (e.g. DATE to DATETIME, INT to BIGINT, etc).
+    Otherwise Predicant_to_list_comparator will treat sub-types of the same
+    super-type as different data types and won't be able to use bisection in
+    many cases.
+  */
+  set_handler(items[0]->type_handler()->type_handler_for_comparison());
+  for (uint i= 1 ; i < nitems ; i++)
+  {
+    unsigned_count+= items[i]->unsigned_flag;
+    if (aggregate_for_comparison(items[i]->type_handler()->
+                                 type_handler_for_comparison()))
+    {
+      /*
+        For more precise error messages if aggregation failed on the first pair
+        {items[0],items[1]}, use the name of items[0]->data_handler().
+        Otherwise use the name of this->type_handler(), which is already a
+        result of aggregation for items[0]..items[i-1].
+      */
+      my_error(ER_ILLEGAL_PARAMETER_DATA_TYPES2_FOR_OPERATION, MYF(0),
+               i == 1 ? items[0]->type_handler()->name().ptr() :
+                        type_handler()->name().ptr(),
+               items[i]->type_handler()->name().ptr(),
+               funcname.str);
+      return true;
+    }
+    /*
+      When aggregating types of two row expressions we have to check
+      that they have the same cardinality and that each component
+      of the first row expression has a compatible row signature with
+      the signature of the corresponding component of the second row
+      expression.
+    */ 
+    if (cmp_type() == ROW_RESULT && cmp_row_type(items[0], items[i]))
+      return true;     // error found: invalid usage of rows
+  }
+  /**
+    If all arguments are of INT type but have different unsigned_flag values,
+    switch to DECIMAL_RESULT.
+  */
+  if (int_uint_as_dec &&
+      cmp_type() == INT_RESULT &&
+      unsigned_count != nitems && unsigned_count != 0)
+    set_handler(&type_handler_newdecimal);
+  return 0;
+}
+
+
+/*
+  Collects different types for comparison of first item with each other items
+
+  SYNOPSIS
+    collect_cmp_types()
+      items             Array of items to collect types from
+      nitems            Number of items in the array
+      skip_nulls        Don't collect types of NULL items if TRUE
+
+  DESCRIPTION
+    This function collects different result types for comparison of the first
+    item in the list with each of the remaining items in the 'items' array.
+
+  RETURN
+    0 - if row type incompatibility has been detected (see cmp_row_type)
+    Bitmap of collected types - otherwise
+*/
+
+static uint collect_cmp_types(Item **items, uint nitems, bool skip_nulls= FALSE)
+{
+  uint i;
+  uint found_types;
+  Item_result left_cmp_type= items[0]->cmp_type();
+  DBUG_ASSERT(nitems > 1);
+  found_types= 0;
+  for (i= 1; i < nitems ; i++)
+  {
+    if (skip_nulls && items[i]->type() == Item::NULL_ITEM)
+      continue; // Skip NULL constant items
+    if ((left_cmp_type == ROW_RESULT ||
+         items[i]->cmp_type() == ROW_RESULT) &&
+        cmp_row_type(items[0], items[i]))
+      return 0;
+    found_types|= 1U << (uint) item_cmp_type(left_cmp_type, items[i]);
+  }
+  /*
+   Even if all right-hand items are NULLs and we are skipping them all, we need
+   at least one type bit in the found_type bitmask.
+  */
+  if (skip_nulls && !found_types)
+    found_types= 1U << (uint) left_cmp_type;
+  return found_types;
+}
+
+
+/*
+  Test functions
+  Most of these  returns 0LL if false and 1LL if true and
+  NULL if some arg is NULL.
+*/
+
+longlong Item_func_not::val_int()
+{
+  DBUG_ASSERT(fixed());
+  bool value= args[0]->val_bool();
+  null_value=args[0]->null_value;
+  return ((!null_value && value == 0) ? 1 : 0);
+}
+
+void Item_func_not::print(String *str, enum_query_type query_type)
+{
+  str->append('!');
+  args[0]->print_parenthesised(str, query_type, precedence());
+}
+
+/**
+  special NOT for ALL subquery.
+*/
+
+
+longlong Item_func_not_all::val_int()
+{
+  DBUG_ASSERT(fixed());
+  bool value= args[0]->val_bool();
+
+  /*
+    return TRUE if there was records in underlying select in max/min
+    optimization (ALL subquery)
+  */
+  if (empty_underlying_subquery())
+    return 1;
+
+  null_value= args[0]->null_value;
+  return ((!null_value && value == 0) ? 1 : 0);
+}
+
+
+bool Item_func_not_all::empty_underlying_subquery()
+{
+  return ((test_sum_item && !test_sum_item->any_value()) ||
+          (test_sub_item && !test_sub_item->any_value()));
+}
+
+void Item_func_not_all::print(String *str, enum_query_type query_type)
+{
+  if (show)
+    Item_func::print(str, query_type);
+  else
+    args[0]->print(str, query_type);
+}
+
+
+/**
+  Special NOP (No OPeration) for ALL subquery. It is like
+  Item_func_not_all.
+
+  @return
+    (return TRUE if underlying subquery do not return rows) but if subquery
+    returns some rows it return same value as argument (TRUE/FALSE).
+*/
+
+longlong Item_func_nop_all::val_int()
+{
+  DBUG_ASSERT(fixed());
+  longlong value= args[0]->val_int();
+
+  /*
+    return FALSE if there was records in underlying select in max/min
+    optimization (SAME/ANY subquery)
+  */
+  if (empty_underlying_subquery())
+    return 0;
+
+  null_value= args[0]->null_value;
+  return (null_value || value == 0) ? 0 : 1;
+}
+
+
+/**
+  Convert a constant item to an int and replace the original item.
+
+    The function converts a constant expression or string to an integer.
+    On successful conversion the original item is substituted for the
+    result of the item evaluation.
+    This is done when comparing DATE/TIME of different formats and
+    also when comparing bigint to strings (in which case strings
+    are converted to bigints).
+
+  @param  thd             thread handle
+  @param  field           item will be converted using the type of this field
+  @param[in,out] item     reference to the item to convert
+
+  @note
+    This function is called only at prepare stage.
+    As all derived tables are filled only after all derived tables
+    are prepared we do not evaluate items with subselects here because
+    they can contain derived tables and thus we may attempt to use a
+    table that has not been populated yet.
+
+  @retval
+    0  Can't convert item
+  @retval
+    1  Item was replaced with an integer version of the item
+*/
+
+static bool convert_const_to_int(THD *thd, Item_field *field_item,
+                                  Item **item)
+{
+  Field *field= field_item->field;
+  int result= 0;
+
+  /*
+    We don't need to convert an integer to an integer,
+    pretend it's already converted.
+
+    But we still convert it if it is compared with a Field_year,
+    as YEAR(2) may change the value of an integer when converting it
+    to an integer (say, 0 to 70).
+  */
+  if ((*item)->cmp_type() == INT_RESULT &&
+      field_item->field_type() != MYSQL_TYPE_YEAR)
+    return 1;
+
+  /*
+    Replace (*item) with its value if the item can be computed.
+
+    Do not replace items that contain aggregate functions:
+    There can be such items that are constants, e.g. COLLATION(AVG(123)),
+    but this function is called at Name Resolution phase.
+    Removing aggregate functions may confuse query plan generation code, e.g.
+    the optimizer might conclude that the query doesn't need to do grouping
+    at all.
+  */
+  if ((*item)->can_eval_in_optimize() &&
+      !(*item)->with_sum_func())
+  {
+    TABLE *table= field->table;
+    Use_relaxed_field_copy urfc(thd);
+    MY_BITMAP *old_maps[2] = { NULL, NULL };
+    ulonglong UNINIT_VAR(orig_field_val); /* original field value if valid */
+    bool save_field_value;
+
+    /* table->read_set may not be set if we come here from a CREATE TABLE */
+    if (table && table->read_set)
+      dbug_tmp_use_all_columns(table, old_maps,
+                               &table->read_set, &table->write_set);
+
+    /*
+      Store the value of the field/constant because the call to save_in_field
+      below overrides that value. Don't save field value if no data has been
+      read yet.
+    */
+    save_field_value= (field_item->const_item() ||
+                       !(field->table->status & STATUS_NO_RECORD));
+    if (save_field_value)
+      orig_field_val= field->val_int();
+    if (!(*item)->save_in_field(field, 1) && !field->is_null())
+    {
+      int field_cmp= 0;
+      // If item is a decimal value, we must reject it if it was truncated.
+      if (field->type() == MYSQL_TYPE_LONGLONG)
+      {
+        field_cmp= stored_field_cmp_to_item(thd, field, *item);
+        DBUG_PRINT("info", ("convert_const_to_int %d", field_cmp));
+      }
+
+      if (0 == field_cmp)
+      {
+        Item *tmp= (new (thd->mem_root)
+                    Item_int_with_ref(thd, field->val_int(), *item,
+                                      MY_TEST(field->flags & UNSIGNED_FLAG)));
+        if (tmp)
+          thd->change_item_tree(item, tmp);
+        result= 1;					// Item was replaced
+      }
+    }
+    /* Restore the original field value. */
+    if (save_field_value)
+    {
+      result= field->store(orig_field_val, TRUE);
+      /* orig_field_val must be a valid value that can be restored back. */
+      DBUG_ASSERT(!result);
+    }
+    if (table && table->read_set)
+      dbug_tmp_restore_column_maps(&table->read_set, &table->write_set, old_maps);
+  }
+  return result;
+}
+
+
+/*
+  Make a special case of compare with fields to get nicer comparisons
+  of bigint numbers with constant string.
+  This directly contradicts the manual (number and a string should
+  be compared as doubles), but seems to provide more
+  "intuitive" behavior in some cases (but less intuitive in others).
+*/
+void Item_func::convert_const_compared_to_int_field(THD *thd)
+{
+  DBUG_ASSERT(arg_count >= 2); // Item_func_nullif has arg_count == 3
+  if (!thd->lex->is_ps_or_view_context_analysis())
+  {
+    int field;
+    if (args[field= 0]->real_item()->type() == FIELD_ITEM ||
+        args[field= 1]->real_item()->type() == FIELD_ITEM)
+    {
+      Item_field *field_item= (Item_field*) (args[field]->real_item());
+      if (((field_item->field_type() == MYSQL_TYPE_LONGLONG &&
+            field_item->type_handler() != &type_handler_vers_trx_id) ||
+           field_item->field_type() ==  MYSQL_TYPE_YEAR))
+        convert_const_to_int(thd, field_item, &args[!field]);
+    }
+  }
+}
+
+
+/*
+  Iterate through arguments and compare them to the original arguments
+  in "old_args". If some argument was replaced:
+  - from Item_field pointing to an indexed Field
+  - to something else (for example, Item_func_conv_charset)
+  then we cannot use Field's indexes for range access any more.
+  Raise a note in this case.
+
+  Note, the number of arguments in "old_args" can be smaller than arg_count.
+  For example, for LIKE, BETWEEN, IN we pass only args[0] in old_args.
+
+  For a comparison predicate we pass both args[0] and args[1] to cover both:
+  - WHERE field=expr
+  - WHERE expr=field
+*/
+
+void Item_bool_func::raise_note_if_key_become_unused(THD *thd, const Item_args &old_args)
+{
+  if (!(thd->variables.note_verbosity & NOTE_VERBOSITY_UNUSABLE_KEYS))
+    return;
+
+  DBUG_ASSERT(old_args.argument_count() <= arg_count);
+  for (uint i= 0; i < old_args.argument_count(); i++)
+  {
+    if (args[i] != old_args.arguments()[i])
+    {
+      DBUG_ASSERT(old_args.arguments()[i]->fixed());
+      Item *real_item= old_args.arguments()[i]->real_item();
+      if (real_item->type() == Item::FIELD_ITEM)
+      {
+        Field *field= static_cast<Item_field*>(real_item)->field;
+        if (field->flags & PART_KEY_FLAG)
+        {
+          /*
+            It used to be Item_field (with indexes!) before the condition
+            rewrite. Now it's something else. Cannot use indexes any more.
+          */
+          field->raise_note_key_become_unused(thd, Print(this, QT_EXPLAIN));
+        }
+      }
+    }
+  }
+}
+
+
+bool Item_func::setup_args_and_comparator(THD *thd, Arg_comparator *cmp)
+{
+  DBUG_ASSERT(arg_count >= 2); // Item_func_nullif has arg_count == 3
+
+  if (args[0]->cmp_type() == STRING_RESULT &&
+      args[1]->cmp_type() == STRING_RESULT)
+  {
+    CHARSET_INFO *tmp;
+    /*
+      Use charset narrowing only for equalities, as that would allow
+      to construct ref access.
+      Non-equality comparisons with constants work without charset narrowing,
+      the constant gets converted.
+      Non-equality comparisons with non-constants would need narrowing to
+      enable range optimizer to handle e.g.
+        t1.mb3key_col <= const_table.mb4_col
+      But this doesn't look important.
+    */
+    bool allow_narrowing= MY_TEST(functype()==Item_func::EQ_FUNC ||
+                                  functype()==Item_func::EQUAL_FUNC);
+
+    if (agg_arg_charsets_for_comparison(&tmp, &args[0], &args[1],
+                                        allow_narrowing))
+      return true;
+    cmp->m_compare_collation= tmp;
+  }
+  //  Convert constants when compared to int/year field
+  DBUG_ASSERT(functype() != LIKE_FUNC);
+  convert_const_compared_to_int_field(thd);
+
+  return cmp->set_cmp_func(thd, this, &args[0], &args[1], true);
+}
+
+
+/*
+  Comparison operators remove arguments' dependency on PAD_CHAR_TO_FULL_LENGTH
+  in case of PAD SPACE comparison collations: trailing spaces do not affect
+  the comparison result for such collations.
+*/
+Sql_mode_dependency
+Item_bool_rowready_func2::value_depends_on_sql_mode() const
+{
+  if (compare_collation()->state & MY_CS_NOPAD)
+    return Item_func::value_depends_on_sql_mode();
+  return ((args[0]->value_depends_on_sql_mode() |
+           args[1]->value_depends_on_sql_mode()) &
+          Sql_mode_dependency(~0, ~MODE_PAD_CHAR_TO_FULL_LENGTH)).
+         soft_to_hard();
+}
+
+
+bool Item_bool_rowready_func2::fix_length_and_dec(THD *thd)
+{
+  max_length= 1;				     // Function returns 0 or 1
+
+  /*
+    As some compare functions are generated after sql_yacc,
+    we have to check for out of memory conditions here
+  */
+  if (!args[0] || !args[1])
+    return FALSE;
+  Item_args old_args(args[0], args[1]);
+  if (setup_args_and_comparator(thd, &cmp))
+    return true;
+  raise_note_if_key_become_unused(thd, old_args);
+  return false;
+}
+
+
+/**
+  Prepare the comparator (set the comparison function) for comparing
+  items *a1 and *a2 in the context of 'type'.
+
+  @param[in]      owner_arg  Item, peforming the comparison (e.g. Item_func_eq)
+  @param[in,out]  a1         first argument to compare
+  @param[in,out]  a2         second argument to compare
+  @param[in]      type       type context to compare in
+
+  Both *a1 and *a2 can be replaced by this method - typically by constant
+  items, holding the cached converted value of the original (constant) item.
+*/
+
+int Arg_comparator::set_cmp_func(THD *thd, Item_func_or_sum *owner_arg,
+                                 Item **a1, Item **a2)
+{
+  owner= owner_arg;
+  set_null= set_null && owner_arg;
+  a= a1;
+  b= a2;
+  Item *tmp_args[2]= {*a1, *a2};
+  Type_handler_hybrid_field_type tmp;
+  if (tmp.aggregate_for_comparison(owner_arg->func_name_cstring(), tmp_args, 2,
+                                   false))
+  {
+    DBUG_ASSERT(thd->is_error());
+    return 1;
+  }
+  m_compare_handler= tmp.type_handler();
+  return m_compare_handler->set_comparator_func(thd, this);
+}
+
+
+bool Arg_comparator::set_cmp_func_for_row_arguments(THD *thd)
+{
+  uint n= (*a)->cols();
+  if (n != (*b)->cols())
+  {
+    my_error(ER_OPERAND_COLUMNS, MYF(0), n);
+    comparators= 0;
+    return true;
+  }
+  if (!(comparators= new (thd->mem_root) Arg_comparator[n]))
+    return true;
+  for (uint i=0; i < n; i++)
+  {
+    if ((*a)->element_index(i)->cols() != (*b)->element_index(i)->cols())
+    {
+      my_error(ER_OPERAND_COLUMNS, MYF(0), (*a)->element_index(i)->cols());
+      return true;
+    }
+    if (comparators[i].set_cmp_func(thd, owner, (*a)->addr(i),
+                                    (*b)->addr(i), set_null))
+      return true;
+  }
+  return false;
+}
+
+
+bool Arg_comparator::set_cmp_func_row(THD *thd)
+{
+  func= is_owner_equal_func() ? &Arg_comparator::compare_e_row :
+                                &Arg_comparator::compare_row;
+  return set_cmp_func_for_row_arguments(thd);
+}
+
+
+bool Arg_comparator::set_cmp_func_string(THD *thd)
+{
+  func= is_owner_equal_func() ? &Arg_comparator::compare_e_string :
+                                &Arg_comparator::compare_string;
+  if (compare_type() == STRING_RESULT &&
+      (*a)->result_type() == STRING_RESULT &&
+      (*b)->result_type() == STRING_RESULT)
+  {
+    /*
+      We must set cmp_collation here as we may be called from for an automatic
+      generated item, like in natural join.
+      Allow reinterpted superset as subset.
+    */
+    bool allow_narrowing= false;
+    if (owner->type() == Item::FUNC_ITEM)
+    {
+      Item_func::Functype ftype= ((Item_func*)owner)->functype();
+      if (ftype == Item_func::EQUAL_FUNC || ftype==Item_func::EQ_FUNC)
+        allow_narrowing= true;
+    }
+
+    if (owner->agg_arg_charsets_for_comparison(&m_compare_collation, a, b,
+                                               allow_narrowing))
+      return true;
+
+    if ((*a)->type() == Item::FUNC_ITEM &&
+        ((Item_func *) (*a))->functype() == Item_func::JSON_EXTRACT_FUNC)
+    {
+      func= is_owner_equal_func() ? &Arg_comparator::compare_e_json_str:
+                                    &Arg_comparator::compare_json_str;
+      return 0;
+    }
+    else if ((*b)->type() == Item::FUNC_ITEM &&
+             ((Item_func *) (*b))->functype() == Item_func::JSON_EXTRACT_FUNC)
+    {
+      func= is_owner_equal_func() ? &Arg_comparator::compare_e_json_str:
+                                    &Arg_comparator::compare_str_json;
+      return 0;
+    }
+  }
+
+  a= cache_converted_constant(thd, a, &a_cache, compare_type_handler());
+  b= cache_converted_constant(thd, b, &b_cache, compare_type_handler());
+  return false;
+}
+
+
+bool Arg_comparator::set_cmp_func_time(THD *thd)
+{
+  m_compare_collation= &my_charset_numeric;
+  func= is_owner_equal_func() ? &Arg_comparator::compare_e_time :
+                                &Arg_comparator::compare_time;
+  a= cache_converted_constant(thd, a, &a_cache, compare_type_handler());
+  b= cache_converted_constant(thd, b, &b_cache, compare_type_handler());
+  return false;
+}
+
+
+bool Arg_comparator::set_cmp_func_datetime(THD *thd)
+{
+  m_compare_collation= &my_charset_numeric;
+  func= is_owner_equal_func() ? &Arg_comparator::compare_e_datetime :
+                                &Arg_comparator::compare_datetime;
+  a= cache_converted_constant(thd, a, &a_cache, compare_type_handler());
+  b= cache_converted_constant(thd, b, &b_cache, compare_type_handler());
+  return false;
+}
+
+
+bool Arg_comparator::set_cmp_func_native(THD *thd)
+{
+  m_compare_collation= &my_charset_numeric;
+  func= is_owner_equal_func() ? &Arg_comparator::compare_e_native :
+                                &Arg_comparator::compare_native;
+  a= cache_converted_constant(thd, a, &a_cache, compare_type_handler());
+  b= cache_converted_constant(thd, b, &b_cache, compare_type_handler());
+  return false;
+}
+
+
+bool Arg_comparator::set_cmp_func_int(THD *thd)
+{
+  func= is_owner_equal_func() ? &Arg_comparator::compare_e_int :
+                                &Arg_comparator::compare_int_signed;
+  if ((*a)->field_type() == MYSQL_TYPE_YEAR &&
+      (*b)->field_type() == MYSQL_TYPE_YEAR)
+  {
+    func= is_owner_equal_func() ? &Arg_comparator::compare_e_datetime :
+                                  &Arg_comparator::compare_datetime;
+  }
+  else if (func == &Arg_comparator::compare_int_signed)
+  {
+    if ((*a)->unsigned_flag)
+      func= (((*b)->unsigned_flag)?
+             &Arg_comparator::compare_int_unsigned :
+             &Arg_comparator::compare_int_unsigned_signed);
+    else if ((*b)->unsigned_flag)
+      func= &Arg_comparator::compare_int_signed_unsigned;
+  }
+  else if (func== &Arg_comparator::compare_e_int)
+  {
+    if ((*a)->unsigned_flag ^ (*b)->unsigned_flag)
+      func= &Arg_comparator::compare_e_int_diff_signedness;
+  }
+  a= cache_converted_constant(thd, a, &a_cache, compare_type_handler());
+  b= cache_converted_constant(thd, b, &b_cache, compare_type_handler());
+  return false;
+}
+
+
+bool Arg_comparator::set_cmp_func_real(THD *thd)
+{
+  if ((((*a)->result_type() == DECIMAL_RESULT && !(*a)->const_item() &&
+        (*b)->result_type() == STRING_RESULT  &&  (*b)->const_item()) ||
+      ((*b)->result_type() == DECIMAL_RESULT && !(*b)->const_item() &&
+       (*a)->result_type() == STRING_RESULT  &&  (*a)->const_item())))
+  {
+    /*
+     <non-const decimal expression> <cmp> <const string expression>
+     or
+     <const string expression> <cmp> <non-const decimal expression>
+
+     Do comparison as decimal rather than float, in order not to lose precision.
+    */
+    m_compare_handler= &type_handler_newdecimal;
+    return set_cmp_func_decimal(thd);
+  }
+
+  func= is_owner_equal_func() ? &Arg_comparator::compare_e_real :
+                                &Arg_comparator::compare_real;
+  if ((*a)->decimals < NOT_FIXED_DEC && (*b)->decimals < NOT_FIXED_DEC)
+  {
+    precision= 5 / log_10[MY_MAX((*a)->decimals, (*b)->decimals) + 1];
+    if (func == &Arg_comparator::compare_real)
+      func= &Arg_comparator::compare_real_fixed;
+    else if (func == &Arg_comparator::compare_e_real)
+      func= &Arg_comparator::compare_e_real_fixed;
+  }
+  a= cache_converted_constant(thd, a, &a_cache, compare_type_handler());
+  b= cache_converted_constant(thd, b, &b_cache, compare_type_handler());
+  return false;
+}
+
+bool Arg_comparator::set_cmp_func_decimal(THD *thd)
+{
+  func= is_owner_equal_func() ? &Arg_comparator::compare_e_decimal :
+                                &Arg_comparator::compare_decimal;
+  a= cache_converted_constant(thd, a, &a_cache, compare_type_handler());
+  b= cache_converted_constant(thd, b, &b_cache, compare_type_handler());
+  return false;
+}
+
+
+/**
+  Convert and cache a constant.
+
+  @param value      [in]  An item to cache
+  @param cache_item [out] Placeholder for the cache item
+  @param type       [in]  Comparison type
+
+  @details
+    When given item is a constant and its type differs from comparison type
+    then cache its value to avoid type conversion of this constant on each
+    evaluation. In this case the value is cached and the reference to the cache
+    is returned.
+    Original value is returned otherwise.
+
+  @return cache item or original value.
+*/
+
+Item** Arg_comparator::cache_converted_constant(THD *thd_arg, Item **value,
+                                                Item **cache_item,
+                                                const Type_handler *handler)
+{
+  /*
+    Don't need cache if doing context analysis only.
+  */
+  if (!thd_arg->lex->is_ps_or_view_context_analysis() &&
+      (*value)->const_item() &&
+      handler->type_handler_for_comparison() !=
+      (*value)->type_handler_for_comparison())
+  {
+    Item_cache *cache= handler->Item_get_cache(thd_arg, *value);
+    cache->setup(thd_arg, *value);
+    *cache_item= cache;
+    return cache_item;
+  }
+  return value;
+}
+
+
+int Arg_comparator::compare_time()
+{
+  THD *thd= current_thd;
+  longlong val1= (*a)->val_time_packed(thd);
+  if (!(*a)->null_value)
+  {
+    longlong val2= (*b)->val_time_packed(thd);
+    if (!(*b)->null_value)
+      return compare_not_null_values(val1, val2);
+  }
+  if (set_null)
+    owner->null_value= true;
+  return -1;
+}
+
+
+int Arg_comparator::compare_e_time()
+{
+  THD *thd= current_thd;
+  longlong val1= (*a)->val_time_packed(thd);
+  longlong val2= (*b)->val_time_packed(thd);
+  if ((*a)->null_value || (*b)->null_value)
+    return MY_TEST((*a)->null_value && (*b)->null_value);
+  return MY_TEST(val1 == val2);
+}
+
+
+
+int Arg_comparator::compare_datetime()
+{
+  THD *thd= current_thd;
+  longlong val1= (*a)->val_datetime_packed(thd);
+  if (!(*a)->null_value)
+  {
+    longlong val2= (*b)->val_datetime_packed(thd);
+    if (!(*b)->null_value)
+      return compare_not_null_values(val1, val2);
+  }
+  if (set_null)
+    owner->null_value= true;
+  return -1;
+}
+
+
+int Arg_comparator::compare_e_datetime()
+{
+  THD *thd= current_thd;
+  longlong val1= (*a)->val_datetime_packed(thd);
+  longlong val2= (*b)->val_datetime_packed(thd);
+  if ((*a)->null_value || (*b)->null_value)
+    return MY_TEST((*a)->null_value && (*b)->null_value);
+  return MY_TEST(val1 == val2);
+}
+
+
+int Arg_comparator::compare_string()
+{
+  String *res1,*res2;
+  if ((res1= (*a)->val_str(&value1)))
+  {
+    if ((res2= (*b)->val_str(&value2)))
+    {
+      if (set_null)
+        owner->null_value= 0;
+      return sortcmp(res1, res2, compare_collation());
+    }
+  }
+  if (set_null)
+    owner->null_value= 1;
+  return -1;
+}
+
+
+/**
+  Compare strings, but take into account that NULL == NULL.
+*/
+
+
+int Arg_comparator::compare_e_string()
+{
+  String *res1,*res2;
+  res1= (*a)->val_str(&value1);
+  DBUG_ASSERT((res1 == NULL) == (*a)->null_value);
+  res2= (*b)->val_str(&value2);
+  DBUG_ASSERT((res2 == NULL) == (*b)->null_value);
+  if (!res1 || !res2)
+    return MY_TEST(res1 == res2);
+  return MY_TEST(sortcmp(res1, res2, compare_collation()) == 0);
+}
+
+
+int Arg_comparator::compare_native()
+{
+  THD *thd= current_thd;
+  if (!(*a)->val_native_with_conversion(thd, &m_native1,
+                                        compare_type_handler()))
+  {
+    if (!(*b)->val_native_with_conversion(thd, &m_native2,
+                                          compare_type_handler()))
+    {
+      if (set_null)
+        owner->null_value= 0;
+      return compare_type_handler()->cmp_native(m_native1, m_native2);
+    }
+  }
+  if (set_null)
+    owner->null_value= 1;
+  return -1;
+}
+
+
+int Arg_comparator::compare_e_native()
+{
+  THD *thd= current_thd;
+  bool res1= (*a)->val_native_with_conversion(thd, &m_native1,
+                                              compare_type_handler());
+  bool res2= (*b)->val_native_with_conversion(thd, &m_native2,
+                                              compare_type_handler());
+  if (res1 || res2)
+    return MY_TEST(res1 == res2);
+  return MY_TEST(compare_type_handler()->cmp_native(m_native1, m_native2) == 0);
+}
+
+
+int Arg_comparator::compare_real()
+{
+  /*
+    Fix yet another manifestation of Bug#2338. 'Volatile' will instruct
+    gcc to flush double values out of 80-bit Intel FPU registers before
+    performing the comparison.
+  */
+  volatile double val1, val2;
+  val1= (*a)->val_real();
+  if (!(*a)->null_value)
+  {
+    val2= (*b)->val_real();
+    if (!(*b)->null_value)
+    {
+      if (set_null)
+        owner->null_value= 0;
+      if (val1 < val2)	return -1;
+      if (val1 == val2) return 0;
+      return 1;
+    }
+  }
+  if (set_null)
+    owner->null_value= 1;
+  return -1;
+}
+
+int Arg_comparator::compare_decimal()
+{
+  VDec val1(*a);
+  if (!val1.is_null())
+  {
+    VDec val2(*b);
+    if (!val2.is_null())
+    {
+      if (set_null)
+        owner->null_value= 0;
+      val1.round_self_if_needed((*a)->decimals, HALF_UP);
+      val2.round_self_if_needed((*b)->decimals, HALF_UP);
+      return val1.cmp(val2);
+    }
+  }
+  if (set_null)
+    owner->null_value= 1;
+  return -1;
+}
+
+int Arg_comparator::compare_e_real()
+{
+  double val1= (*a)->val_real();
+  double val2= (*b)->val_real();
+  if ((*a)->null_value || (*b)->null_value)
+    return MY_TEST((*a)->null_value && (*b)->null_value);
+  return MY_TEST(val1 == val2);
+}
+
+int Arg_comparator::compare_e_decimal()
+{
+  VDec val1(*a), val2(*b);
+  if (val1.is_null() || val2.is_null())
+    return MY_TEST(val1.is_null() && val2.is_null());
+  val1.round_self_if_needed((*a)->decimals, HALF_UP);
+  val2.round_self_if_needed((*b)->decimals, HALF_UP);
+  return MY_TEST(val1.cmp(val2) == 0);
+}
+
+
+int Arg_comparator::compare_real_fixed()
+{
+  /*
+    Fix yet another manifestation of Bug#2338. 'Volatile' will instruct
+    gcc to flush double values out of 80-bit Intel FPU registers before
+    performing the comparison.
+  */
+  volatile double val1, val2;
+  val1= (*a)->val_real();
+  if (!(*a)->null_value)
+  {
+    val2= (*b)->val_real();
+    if (!(*b)->null_value)
+    {
+      if (set_null)
+        owner->null_value= 0;
+      if (val1 == val2 || fabs(val1 - val2) < precision)
+        return 0;
+      if (val1 < val2)
+        return -1;
+      return 1;
+    }
+  }
+  if (set_null)
+    owner->null_value= 1;
+  return -1;
+}
+
+
+int Arg_comparator::compare_e_real_fixed()
+{
+  double val1= (*a)->val_real();
+  double val2= (*b)->val_real();
+  if ((*a)->null_value || (*b)->null_value)
+    return MY_TEST((*a)->null_value && (*b)->null_value);
+  return MY_TEST(val1 == val2 || fabs(val1 - val2) < precision);
+}
+
+
+int Arg_comparator::compare_int_signed()
+{
+  longlong val1= (*a)->val_int();
+  if (!(*a)->null_value)
+  {
+    longlong val2= (*b)->val_int();
+    if (!(*b)->null_value)
+      return compare_not_null_values(val1, val2);
+  }
+  if (set_null)
+    owner->null_value= 1;
+  return -1;
+}
+
+
+/**
+  Compare values as BIGINT UNSIGNED.
+*/
+
+int Arg_comparator::compare_int_unsigned()
+{
+  ulonglong val1= (*a)->val_int();
+  if (!(*a)->null_value)
+  {
+    ulonglong val2= (*b)->val_int();
+    if (!(*b)->null_value)
+    {
+      if (set_null)
+        owner->null_value= 0;
+      if (val1 < val2)	return -1;
+      if (val1 == val2)   return 0;
+      return 1;
+    }
+  }
+  if (set_null)
+    owner->null_value= 1;
+  return -1;
+}
+
+
+/**
+  Compare signed (*a) with unsigned (*B)
+*/
+
+int Arg_comparator::compare_int_signed_unsigned()
+{
+  longlong sval1= (*a)->val_int();
+  if (!(*a)->null_value)
+  {
+    ulonglong uval2= (ulonglong)(*b)->val_int();
+    if (!(*b)->null_value)
+    {
+      if (set_null)
+        owner->null_value= 0;
+      if (sval1 < 0 || (ulonglong)sval1 < uval2)
+        return -1;
+      if ((ulonglong)sval1 == uval2)
+        return 0;
+      return 1;
+    }
+  }
+  if (set_null)
+    owner->null_value= 1;
+  return -1;
+}
+
+
+/**
+  Compare unsigned (*a) with signed (*B)
+*/
+
+int Arg_comparator::compare_int_unsigned_signed()
+{
+  ulonglong uval1= (ulonglong)(*a)->val_int();
+  if (!(*a)->null_value)
+  {
+    longlong sval2= (*b)->val_int();
+    if (!(*b)->null_value)
+    {
+      if (set_null)
+        owner->null_value= 0;
+      if (sval2 < 0)
+        return 1;
+      if (uval1 < (ulonglong)sval2)
+        return -1;
+      if (uval1 == (ulonglong)sval2)
+        return 0;
+      return 1;
+    }
+  }
+  if (set_null)
+    owner->null_value= 1;
+  return -1;
+}
+
+
+int Arg_comparator::compare_e_int()
+{
+  longlong val1= (*a)->val_int();
+  longlong val2= (*b)->val_int();
+  if ((*a)->null_value || (*b)->null_value)
+    return MY_TEST((*a)->null_value && (*b)->null_value);
+  return MY_TEST(val1 == val2);
+}
+
+/**
+  Compare unsigned *a with signed *b or signed *a with unsigned *b.
+*/
+int Arg_comparator::compare_e_int_diff_signedness()
+{
+  longlong val1= (*a)->val_int();
+  longlong val2= (*b)->val_int();
+  if ((*a)->null_value || (*b)->null_value)
+    return MY_TEST((*a)->null_value && (*b)->null_value);
+  return (val1 >= 0) && MY_TEST(val1 == val2);
+}
+
+int Arg_comparator::compare_row()
+{
+  int res= 0;
+  bool was_null= 0;
+  (*a)->bring_value();
+  (*b)->bring_value();
+
+  if ((*a)->null_value || (*b)->null_value)
+  {
+    owner->null_value= 1;
+    return -1;
+  }
+
+  uint n= (*a)->cols();
+  for (uint i= 0; i<n; i++)
+  {
+    res= comparators[i].compare();
+    /* Aggregate functions don't need special null handling. */
+    if (owner->null_value && owner->type() == Item::FUNC_ITEM)
+    {
+      // NULL was compared
+      switch (((Item_func*)owner)->functype()) {
+      case Item_func::NE_FUNC:
+        break; // NE never aborts on NULL
+      case Item_func::LT_FUNC:
+      case Item_func::LE_FUNC:
+      case Item_func::GT_FUNC:
+      case Item_func::GE_FUNC:
+        return -1; // <, <=, > and >= always fail on NULL
+      case Item_func::EQ_FUNC:
+        if (owner->is_top_level_item())
+          return -1; // We do not need correct NULL returning
+        break;
+      default:
+        DBUG_ASSERT(0);
+        break;
+      }
+      was_null= 1;
+      owner->null_value= 0;
+      res= 0;  // continue comparison (maybe we will meet explicit difference)
+    }
+    else if (res)
+      return res;
+  }
+  if (was_null)
+  {
+    /*
+      There was NULL(s) in comparison in some parts, but there was no
+      explicit difference in other parts, so we have to return NULL.
+    */
+    owner->null_value= 1;
+    return -1;
+  }
+  return 0;
+}
+
+
+int Arg_comparator::compare_e_row()
+{
+  (*a)->bring_value();
+  (*b)->bring_value();
+  uint n= (*a)->cols();
+  for (uint i= 0; i<n; i++)
+  {
+    if (!comparators[i].compare())
+      return 0;
+  }
+  return 1;
+}
+
+
+int Arg_comparator::compare_json_str()
+{
+  return compare_json_str_basic(*a, *b);
+}
+
+
+int Arg_comparator::compare_str_json()
+{
+  return -compare_json_str_basic(*b, *a);
+}
+
+
+int Arg_comparator::compare_e_json_str()
+{
+  return compare_e_json_str_basic(*a, *b);
+}
+
+
+int Arg_comparator::compare_e_str_json()
+{
+  return compare_e_json_str_basic(*b, *a);
+}
+
+
+bool Item_func_truth::fix_length_and_dec(THD *thd)
+{
+  base_flags&= ~item_base_t::MAYBE_NULL;
+  null_value= 0;
+  decimals= 0;
+  max_length= 1;
+  return FALSE;
+}
+
+
+void Item_func_truth::print(String *str, enum_query_type query_type)
+{
+  args[0]->print_parenthesised(str, query_type, precedence());
+  str->append(STRING_WITH_LEN(" is "));
+  if (! affirmative)
+    str->append(STRING_WITH_LEN("not "));
+  if (value)
+    str->append(STRING_WITH_LEN("true"));
+  else
+    str->append(STRING_WITH_LEN("false"));
+}
+
+
+bool Item_func_truth::val_bool()
+{
+  bool val= args[0]->val_bool();
+  if (args[0]->null_value)
+  {
+    /*
+      NULL val IS {TRUE, FALSE} --> FALSE
+      NULL val IS NOT {TRUE, FALSE} --> TRUE
+    */
+    return (! affirmative);
+  }
+
+  if (affirmative)
+  {
+    /* {TRUE, FALSE} val IS {TRUE, FALSE} value */
+    return (val == value);
+  }
+
+  /* {TRUE, FALSE} val IS NOT {TRUE, FALSE} value */
+  return (val != value);
+}
+
+
+longlong Item_func_truth::val_int()
+{
+  return (val_bool() ? 1 : 0);
+}
+
+
+void Item_in_optimizer::fix_after_pullout(st_select_lex *new_parent,
+                                          Item **ref, bool merge)
+{
+  DBUG_ASSERT(fixed());
+  /* This will re-calculate attributes of our Item_in_subselect: */
+  Item_bool_func::fix_after_pullout(new_parent, ref, merge);
+
+  /* Then, re-calculate not_null_tables_cache: */
+  eval_not_null_tables(NULL);
+}
+
+
+bool Item_in_optimizer::eval_not_null_tables(void *opt_arg)
+{
+  not_null_tables_cache= 0;
+  if (is_top_level_item())
+  {
+    /*
+      It is possible to determine NULL-rejectedness of the left arguments
+      of IN only if it is a top-level predicate.
+    */
+    not_null_tables_cache= args[0]->not_null_tables();
+  }
+  return FALSE;
+}
+
+
+bool Item_in_optimizer::find_not_null_fields(table_map allowed)
+{
+  if (!(~allowed & used_tables()) && is_top_level_item())
+  {
+    return args[0]->find_not_null_fields(allowed);
+  }
+  return false;
+}
+
+void Item_in_optimizer::print(String *str, enum_query_type query_type)
+{
+  if (query_type & QT_PARSABLE)
+    args[1]->print(str, query_type);
+  else
+  {
+     restore_first_argument();
+     Item_func::print(str, query_type);
+  }
+}
+
+
+/**
+  "Restore" first argument before fix_fields() call (after it is harmless).
+
+  @Note: Main pointer to left part of IN/ALL/ANY subselect is subselect's
+  lest_expr (see Item_in_optimizer::fix_left) so changes made during
+  fix_fields will be rolled back there which can make
+  Item_in_optimizer::args[0] unusable on second execution before fix_left()
+  call. This call fix the pointer.
+*/
+
+void Item_in_optimizer::restore_first_argument()
+{
+  Item_in_subselect *in_subs= args[1]->get_IN_subquery();
+  if (in_subs)
+    args[0]= in_subs->left_exp();
+}
+
+
+bool Item_in_optimizer::fix_left(THD *thd)
+{
+  DBUG_ENTER("Item_in_optimizer::fix_left");
+  /*
+    Here we will store pointer on place of main storage of left expression.
+    For usual IN (ALL/ANY) it is subquery left_expr.
+    For other cases (MAX/MIN optimization, non-transformed EXISTS (10.0))
+    it is args[0].
+  */
+  Item **ref0= args;
+  if (!invisible_mode())
+  {
+    /*
+       left_expr->fix_fields() may cause left_expr to be substituted for
+       another item. (e.g. an Item_field may be changed into Item_ref). This
+       transformation is undone at the end of statement execution (e.g. the
+       Item_ref is deleted). However, Item_in_optimizer::args[0] may keep
+       the pointer to the post-transformation item. Because of that, on the
+       next execution we need to copy args[1]->left_expr again.
+    */
+    ref0= args[1]->get_IN_subquery()->left_exp_ptr();
+    args[0]= (*ref0);
+  }
+  if ((*ref0)->fix_fields_if_needed(thd, ref0))
+    DBUG_RETURN(1);
+  if (!cache)
+  {
+    Query_arena *arena, backup;
+    arena= thd->activate_stmt_arena_if_needed(&backup);
+
+    bool rc= !(cache= (*ref0)->get_cache(thd));
+
+    if (arena)
+      thd->restore_active_arena(arena, &backup);
+
+    if (rc)
+      DBUG_RETURN(1);
+    cache->keep_array();
+  }
+  /*
+    During fix_field() expression could be substituted.
+    So we copy changes before use
+  */
+  if (args[0] != (*ref0))
+    args[0]= (*ref0);
+  DBUG_PRINT("info", ("actual fix fields"));
+
+  cache->setup(thd, args[0]);
+  if (cache->cols() == 1)
+  {
+    DBUG_ASSERT(args[0]->type() != ROW_ITEM);
+    /* 
+      Note: there can be cases when used_tables()==0 && !const_item(). See
+      Item_sum::update_used_tables for details.
+    */
+    if ((used_tables_cache= args[0]->used_tables()) || !args[0]->const_item())
+      cache->set_used_tables(OUTER_REF_TABLE_BIT);
+    else
+      cache->set_used_tables(0);
+  }
+  else
+  {
+    uint n= cache->cols();
+    for (uint i= 0; i < n; i++)
+    {
+      /* Check that the expression (part of row) do not contain a subquery */
+      if (args[0]->element_index(i)->walk(&Item::is_subquery_processor, 0, 0))
+      {
+        my_error(ER_NOT_SUPPORTED_YET, MYF(0),
+                 "SUBQUERY in ROW in left expression of IN/ALL/ANY");
+        DBUG_RETURN(1);
+      }
+      Item *element=args[0]->element_index(i);
+      if (element->used_tables() || !element->const_item())
+      {
+	((Item_cache *)cache->element_index(i))->
+          set_used_tables(OUTER_REF_TABLE_BIT);
+        cache->set_used_tables(OUTER_REF_TABLE_BIT);
+      }
+      else
+	((Item_cache *)cache->element_index(i))->set_used_tables(0);
+    }
+    used_tables_cache= args[0]->used_tables();
+  }
+  eval_not_null_tables(NULL);
+  with_flags|= (args[0]->with_flags |
+               (args[1]->with_flags & item_with_t::SP_VAR));
+  if ((const_item_cache= args[0]->const_item()))
+  {
+    cache->store(args[0]);
+    cache->cache_value();
+  }
+  if (args[1]->fixed())
+  {
+    /* to avoid overriding is called to update left expression */
+    used_tables_and_const_cache_join(args[1]);
+    with_flags|= args[1]->with_flags & item_with_t::SUM_FUNC;
+  }
+  DBUG_RETURN(0);
+}
+
+
+bool Item_in_optimizer::fix_fields(THD *thd, Item **ref)
+{
+  DBUG_ASSERT(fixed() == 0);
+  Item_subselect *sub= 0;
+  uint col;
+
+  /*
+     MAX/MIN optimization can convert the subquery into
+     expr + Item_singlerow_subselect
+   */
+  if (args[1]->type() == Item::SUBSELECT_ITEM)
+    sub= (Item_subselect *)args[1];
+
+  if (fix_left(thd))
+    return TRUE;
+  if (args[0]->maybe_null())
+    set_maybe_null();
+
+  if (args[1]->fix_fields_if_needed(thd, args + 1))
+    return TRUE;
+  if (!invisible_mode() &&
+      ((sub && ((col= args[0]->cols()) != sub->engine->cols())) ||
+       (!sub && (args[1]->cols() != (col= 1)))))
+  {
+    my_error(ER_OPERAND_COLUMNS, MYF(0), col);
+    return TRUE;
+  }
+
+  base_flags|= (item_base_t::FIXED |
+                (args[1]->base_flags & (item_base_t::MAYBE_NULL |
+                                        item_base_t::AT_TOP_LEVEL)));
+  with_flags|= (item_with_t::SUBQUERY |
+                args[1]->with_flags |
+                (args[0]->with_flags &
+                 (item_with_t::SP_VAR | item_with_t::WINDOW_FUNC)));
+  // The subquery cannot have window functions aggregated in this select
+  DBUG_ASSERT(!args[1]->with_window_func());
+  used_tables_and_const_cache_join(args[1]);
+  return FALSE;
+}
+
+/**
+  Check if Item_in_optimizer should work as a pass-through item for its 
+  arguments.
+
+  @note 
+   Item_in_optimizer should work as pass-through for
+    - subqueries that were processed by ALL/ANY->MIN/MAX rewrite
+    - subqueries that were originally EXISTS subqueries (and were coinverted by
+      the EXISTS->IN rewrite)
+
+   When Item_in_optimizer is not not working as a pass-through, it
+    - caches its "left argument", args[0].
+    - makes adjustments to subquery item's return value for proper NULL
+      value handling
+*/
+
+bool Item_in_optimizer::invisible_mode()
+{
+  /* MAX/MIN transformed or EXISTS->IN prepared => do nothing */
+  return (args[1]->get_IN_subquery() == NULL);
+}
+
+
+/**
+  Add an expression cache for this subquery if it is needed
+
+  @param thd_arg         Thread handle
+
+  @details
+  The function checks whether an expression cache is needed for this item
+  and if if so wraps the item into an item of the class
+  Item_cache_wrapper with an appropriate expression cache set up there.
+
+  @note
+  used from Item::transform()
+
+  @return
+  new wrapper item if an expression cache is needed,
+  this item - otherwise
+*/
+
+Item *Item_in_optimizer::expr_cache_insert_transformer(THD *thd, uchar *unused)
+{
+  DBUG_ENTER("Item_in_optimizer::expr_cache_insert_transformer");
+  DBUG_ASSERT(fixed());
+
+  if (invisible_mode())
+    DBUG_RETURN(this);
+
+  if (expr_cache)
+    DBUG_RETURN(expr_cache);
+
+  if (args[1]->expr_cache_is_needed(thd) &&
+      (expr_cache= set_expr_cache(thd)))
+    DBUG_RETURN(expr_cache);
+
+  DBUG_RETURN(this);
+}
+
+
+
+/**
+    Collect and add to the list cache parameters for this Item.
+
+    @param parameters    The list where to add parameters
+*/
+
+void Item_in_optimizer::get_cache_parameters(List<Item> &parameters)
+{
+  DBUG_ASSERT(fixed());
+  /* Add left expression to the list of the parameters of the subquery */
+  if (!invisible_mode())
+  {
+    if (args[0]->cols() == 1)
+      parameters.add_unique(args[0], &cmp_items);
+    else
+    {
+      for (uint i= 0; i < args[0]->cols(); i++)
+      {
+        parameters.add_unique(args[0]->element_index(i), &cmp_items);
+      }
+    }
+  }
+  args[1]->get_cache_parameters(parameters);
+}
+
+/**
+   The implementation of optimized \<outer expression\> [NOT] IN \<subquery\>
+   predicates. The implementation works as follows.
+
+   For the current value of the outer expression
+   
+   - If it contains only NULL values, the original (before rewrite by the
+     Item_in_subselect rewrite methods) inner subquery is non-correlated and
+     was previously executed, there is no need to re-execute it, and the
+     previous return value is returned.
+
+   - If it contains NULL values, check if there is a partial match for the
+     inner query block by evaluating it. For clarity we repeat here the
+     transformation previously performed on the sub-query. The expression
+
+     <tt>
+     ( oc_1, ..., oc_n ) 
+     \<in predicate\>
+     ( SELECT ic_1, ..., ic_n
+       FROM \<table\>
+       WHERE \<inner where\> 
+     )
+     </tt>
+
+     was transformed into
+     
+     <tt>
+     ( oc_1, ..., oc_n ) 
+     \<in predicate\>
+     ( SELECT ic_1, ..., ic_n 
+       FROM \<table\> 
+       WHERE \<inner where\> AND ... ( ic_k = oc_k OR ic_k IS NULL ) 
+       HAVING ... NOT ic_k IS NULL
+     )
+     </tt>
+
+     The evaluation will now proceed according to special rules set up
+     elsewhere. These rules include:
+
+     - The HAVING NOT \<inner column\> IS NULL conditions added by the
+       aforementioned rewrite methods will detect whether they evaluated (and
+       rejected) a NULL value and if so, will cause the subquery to evaluate
+       to NULL. 
+
+     - The added WHERE and HAVING conditions are present only for those inner
+       columns that correspond to outer column that are not NULL at the moment.
+     
+     - If there is an eligible index for executing the subquery, the special
+       access method "Full scan on NULL key" is employed which ensures that
+       the inner query will detect if there are NULL values resulting from the
+       inner query. This access method will quietly resort to table scan if it
+       needs to find NULL values as well.
+
+     - Under these conditions, the sub-query need only be evaluated in order to
+       find out whether it produced any rows.
+     
+       - If it did, we know that there was a partial match since there are
+         NULL values in the outer row expression.
+
+       - If it did not, the result is FALSE or UNKNOWN. If at least one of the
+         HAVING sub-predicates rejected a NULL value corresponding to an outer
+         non-NULL, and hence the inner query block returns UNKNOWN upon
+         evaluation, there was a partial match and the result is UNKNOWN.
+
+   - If it contains no NULL values, the call is forwarded to the inner query
+     block.
+
+     @see Item_in_subselect::val_bool()
+     @see Item_is_not_null_test::val_int()
+*/
+
+longlong Item_in_optimizer::val_int()
+{
+  bool tmp;
+  DBUG_ASSERT(fixed());
+  cache->store(args[0]);
+  cache->cache_value();
+  DBUG_ENTER(" Item_in_optimizer::val_int");
+
+  if (invisible_mode())
+  {
+    longlong res= args[1]->val_int();
+    null_value= args[1]->null_value;
+    DBUG_PRINT("info", ("pass trough"));
+    DBUG_RETURN(res);
+  }
+
+  if (cache->null_value_inside)
+  {
+     DBUG_PRINT("info", ("Left NULL..."));
+    /*
+      We're evaluating 
+      "<outer_value_list> [NOT] IN (SELECT <inner_value_list>...)" 
+      where one or more of the outer values is NULL. 
+    */
+    if (args[1]->is_top_level_item())
+    {
+      /*
+        We're evaluating a top level item, e.g. 
+	"<outer_value_list> IN (SELECT <inner_value_list>...)",
+	and in this case a NULL value in the outer_value_list means
+        that the result shall be NULL/FALSE (makes no difference for
+        top level items). The cached value is NULL, so just return
+        NULL.
+      */
+      null_value= 1;
+    }
+    else
+    {
+      /*
+	We're evaluating an item where a NULL value in either the
+        outer or inner value list does not automatically mean that we
+        can return NULL/FALSE. An example of such a query is
+        "<outer_value_list> NOT IN (SELECT <inner_value_list>...)" 
+        The result when there is at least one NULL value is: NULL if the
+        SELECT evaluated over the non-NULL values produces at least
+        one row, FALSE otherwise
+      */
+      Item_in_subselect *item_subs= args[1]->get_IN_subquery();
+      bool all_left_cols_null= true;
+      const uint ncols= cache->cols();
+
+      /*
+        Turn off the predicates that are based on column compares for
+        which the left part is currently NULL
+      */
+      for (uint i= 0; i < ncols; i++)
+      {
+        if (cache->element_index(i)->null_value)
+          item_subs->set_cond_guard_var(i, FALSE);
+        else 
+          all_left_cols_null= false;
+      }
+
+      if (!item_subs->is_correlated && 
+          all_left_cols_null && result_for_null_param != UNKNOWN)
+      {
+        /* 
+           This is a non-correlated subquery, all values in the outer
+           value list are NULL, and we have already evaluated the
+           subquery for all NULL values: Return the same result we
+           did last time without evaluating the subquery.
+        */
+        null_value= result_for_null_param;
+      } 
+      else 
+      {
+        /* The subquery has to be evaluated */
+        (void) item_subs->val_bool_result();
+        if (item_subs->engine->no_rows())
+          null_value= item_subs->null_value;
+        else
+          null_value= TRUE;
+        if (all_left_cols_null)
+          result_for_null_param= null_value;
+      }
+
+      /* Turn all predicates back on */
+      for (uint i= 0; i < ncols; i++)
+        item_subs->set_cond_guard_var(i, TRUE);
+    }
+    DBUG_RETURN(0);
+  }
+  tmp= args[1]->val_bool_result();
+  null_value= args[1]->null_value;
+  DBUG_RETURN(tmp);
+}
+
+
+void Item_in_optimizer::cleanup()
+{
+  DBUG_ENTER("Item_in_optimizer::cleanup");
+  Item_bool_func::cleanup();
+  expr_cache= 0;
+  DBUG_VOID_RETURN;
+}
+
+
+bool Item_in_optimizer::is_null()
+{
+  val_int();
+  return null_value;
+}
+
+
+/**
+  Transform an Item_in_optimizer and its arguments with a callback function.
+
+  @param transformer the transformer callback function to be applied to the
+         nodes of the tree of the object
+  @param parameter to be passed to the transformer
+
+  @detail
+    Recursively transform the left and the right operand of this Item. The
+    Right operand is an Item_in_subselect or its subclass. To avoid the
+    creation of new Items, we use the fact the the left operand of the
+    Item_in_subselect is the same as the one of 'this', so instead of
+    transforming its operand, we just assign the left operand of the
+    Item_in_subselect to be equal to the left operand of 'this'.
+    The transformation is not applied further to the subquery operand
+    if the IN predicate.
+
+  @returns
+    @retval pointer to the transformed item
+    @retval NULL if an error occurred
+*/
+
+Item *Item_in_optimizer::transform(THD *thd, Item_transformer transformer,
+                                   uchar *argument)
+{
+  Item *new_item;
+
+  DBUG_ASSERT(fixed());
+  DBUG_ASSERT(!thd->stmt_arena->is_stmt_prepare());
+  DBUG_ASSERT(arg_count == 2);
+
+  /* Transform the left IN operand. */
+  new_item= (*args)->transform(thd, transformer, argument);
+  if (!new_item)
+    return 0;
+  /*
+    THD::change_item_tree() should be called only if the tree was
+    really transformed, i.e. when a new item has been created.
+    Otherwise we'll be allocating a lot of unnecessary memory for
+    change records at each execution.
+  */
+  if ((*args) != new_item)
+    thd->change_item_tree(args, new_item);
+
+  if (invisible_mode())
+  {
+    /* MAX/MIN transformed => pass through */
+    new_item= args[1]->transform(thd, transformer, argument);
+    if (!new_item)
+      return 0;
+    if (args[1] != new_item)
+      thd->change_item_tree(args + 1, new_item);
+  }
+  else
+  {
+    /*
+      Transform the right IN operand which should be an Item_in_subselect or a
+      subclass of it. The left operand of the IN must be the same as the left
+      operand of this Item_in_optimizer, so in this case there is no further
+      transformation, we only make both operands the same.
+      TODO: is it the way it should be?
+    */
+    DBUG_ASSERT((args[1])->type() == Item::SUBSELECT_ITEM &&
+                (((Item_subselect*)(args[1]))->substype() ==
+                 Item_subselect::IN_SUBS ||
+                 ((Item_subselect*)(args[1]))->substype() ==
+                 Item_subselect::ALL_SUBS ||
+                 ((Item_subselect*)(args[1]))->substype() ==
+                 Item_subselect::ANY_SUBS));
+
+    thd->change_item_tree(args[1]->get_IN_subquery()->left_exp_ptr(), args[0]);
+  }
+  return (this->*transformer)(thd, argument);
+}
+
+
+bool Item_in_optimizer::is_expensive_processor(void *arg)
+{
+  DBUG_ASSERT(fixed());
+  return args[0]->is_expensive_processor(arg) ||
+         args[1]->is_expensive_processor(arg);
+}
+
+
+bool Item_in_optimizer::is_expensive()
+{
+  DBUG_ASSERT(fixed());
+  return args[0]->is_expensive() || args[1]->is_expensive();
+}
+
+
+longlong Item_func_eq::val_int()
+{
+  DBUG_ASSERT(fixed());
+  int value= cmp.compare();
+  return value == 0 ? 1 : 0;
+}
+
+
+/** Same as Item_func_eq, but NULL = NULL. */
+
+bool Item_func_equal::fix_length_and_dec(THD *thd)
+{
+  bool rc= Item_bool_rowready_func2::fix_length_and_dec(thd);
+  base_flags&= ~item_base_t::MAYBE_NULL;
+  null_value=0;
+  return rc;
+}
+
+longlong Item_func_equal::val_int()
+{
+  DBUG_ASSERT(fixed());
+  return cmp.compare();
+}
+
+longlong Item_func_ne::val_int()
+{
+  DBUG_ASSERT(fixed());
+  int value= cmp.compare();
+  return value != 0 && !null_value ? 1 : 0;
+}
+
+
+longlong Item_func_ge::val_int()
+{
+  DBUG_ASSERT(fixed());
+  int value= cmp.compare();
+  return value >= 0 ? 1 : 0;
+}
+
+
+longlong Item_func_gt::val_int()
+{
+  DBUG_ASSERT(fixed());
+  int value= cmp.compare();
+  return value > 0 ? 1 : 0;
+}
+
+longlong Item_func_le::val_int()
+{
+  DBUG_ASSERT(fixed());
+  int value= cmp.compare();
+  return value <= 0 && !null_value ? 1 : 0;
+}
+
+
+longlong Item_func_lt::val_int()
+{
+  DBUG_ASSERT(fixed());
+  int value= cmp.compare();
+  return value < 0 && !null_value ? 1 : 0;
+}
+
+
+longlong Item_func_strcmp::val_int()
+{
+  DBUG_ASSERT(fixed());
+  String *a= args[0]->val_str(&value1);
+  String *b= args[1]->val_str(&value2);
+  if (!a || !b)
+  {
+    null_value=1;
+    return 0;
+  }
+  int value= cmp_collation.sortcmp(a, b);
+  null_value=0;
+  return !value ? 0 : (value < 0 ? (longlong) -1 : (longlong) 1);
+}
+
+
+bool Item_func_opt_neg::eq(const Item *item, bool binary_cmp) const
+{
+  /* Assume we don't have rtti */
+  if (this == item)
+    return 1;
+  if (item->type() != FUNC_ITEM)
+    return 0;
+  Item_func *item_func=(Item_func*) item;
+  if (arg_count != item_func->argument_count() ||
+      functype() != item_func->functype())
+    return 0;
+  if (negated != ((Item_func_opt_neg *) item_func)->negated)
+    return 0;
+  return Item_args::eq(item_func, binary_cmp);
+}
+
+
+bool Item_func_interval::fix_fields(THD *thd, Item **ref)
+{
+  if (Item_long_func::fix_fields(thd, ref))
+    return true;
+  for (uint i= 0 ; i < row->cols(); i++)
+  {
+    if (row->element_index(i)->check_cols(1))
+      return true;
+  }
+  return false;
+}
+
+
+bool Item_func_interval::fix_length_and_dec(THD *thd)
+{
+  uint rows= row->cols();
+  
+  use_decimal_comparison= ((row->element_index(0)->result_type() ==
+                            DECIMAL_RESULT) ||
+                           (row->element_index(0)->result_type() ==
+                            INT_RESULT));
+  if (rows > 8)
+  {
+    bool not_null_consts= TRUE;
+
+    for (uint i= 1; not_null_consts && i < rows; i++)
+    {
+      Item *el= row->element_index(i);
+      not_null_consts&= el->const_item() && !el->is_null();
+    }
+
+    if (not_null_consts)
+    {
+      intervals= (interval_range*) current_thd->alloc(sizeof(interval_range) *
+                                                         (rows - 1));
+      if (!intervals)
+        return TRUE;
+
+      if (use_decimal_comparison)
+      {
+        for (uint i= 1; i < rows; i++)
+        {
+          Item *el= row->element_index(i);
+          interval_range *range= intervals + (i-1);
+          if ((el->result_type() == DECIMAL_RESULT) ||
+              (el->result_type() == INT_RESULT))
+          {
+            range->type= DECIMAL_RESULT;
+            range->dec.init();
+            my_decimal *dec= el->val_decimal(&range->dec);
+            if (dec != &range->dec)
+            {
+              range->dec= *dec;
+            }
+          }
+          else
+          {
+            range->type= REAL_RESULT;
+            range->dbl= el->val_real();
+          }
+        }
+      }
+      else
+      {
+        for (uint i= 1; i < rows; i++)
+        {
+          intervals[i-1].dbl= row->element_index(i)->val_real();
+        }
+      }
+    }
+  }
+  base_flags&= ~item_base_t::MAYBE_NULL;
+  max_length= 2;
+  used_tables_and_const_cache_join(row);
+  not_null_tables_cache= row->not_null_tables();
+  with_flags|= row->with_flags;
+  return FALSE;
+}
+
+
+/**
+  Execute Item_func_interval().
+
+  @note
+    If we are doing a decimal comparison, we are evaluating the first
+    item twice.
+
+  @return
+    - -1 if null value,
+    - 0 if lower than lowest
+    - 1 - arg_count-1 if between args[n] and args[n+1]
+    - arg_count if higher than biggest argument
+*/
+
+longlong Item_func_interval::val_int()
+{
+  DBUG_ASSERT(fixed());
+  double value;
+  my_decimal dec_buf, *dec= NULL;
+  uint i;
+
+  if (use_decimal_comparison)
+  {
+    dec= row->element_index(0)->val_decimal(&dec_buf);
+    if (row->element_index(0)->null_value)
+      return -1;
+    my_decimal2double(E_DEC_FATAL_ERROR, dec, &value);
+  }
+  else
+  {
+    value= row->element_index(0)->val_real();
+    if (row->element_index(0)->null_value)
+      return -1;
+  }
+
+  if (intervals)
+  {					// Use binary search to find interval
+    uint start,end;
+    start= 0;
+    end=   row->cols()-2;
+    while (start != end)
+    {
+      uint mid= (start + end + 1) / 2;
+      interval_range *range= intervals + mid;
+      my_bool cmp_result;
+      /*
+        The values in the range interval may have different types,
+        Only do a decimal comparison if the first argument is a decimal
+        and we are comparing against a decimal
+      */
+      if (dec && range->type == DECIMAL_RESULT)
+        cmp_result= my_decimal_cmp(&range->dec, dec) <= 0;
+      else
+        cmp_result= (range->dbl <= value);
+      if (cmp_result)
+	start= mid;
+      else
+	end= mid - 1;
+    }
+    interval_range *range= intervals+start;
+    return ((dec && range->type == DECIMAL_RESULT) ?
+            my_decimal_cmp(dec, &range->dec) < 0 :
+            value < range->dbl) ? 0 : start + 1;
+  }
+
+  for (i=1 ; i < row->cols() ; i++)
+  {
+    Item *el= row->element_index(i);
+    if (use_decimal_comparison &&
+        ((el->result_type() == DECIMAL_RESULT) ||
+         (el->result_type() == INT_RESULT)))
+    {
+      VDec e_dec(el);
+      /* Skip NULL ranges. */
+      if (e_dec.is_null())
+        continue;
+      if (e_dec.cmp(dec) > 0)
+        return i - 1;
+    }
+    else 
+    {
+      double val= el->val_real();
+      /* Skip NULL ranges. */
+      if (el->null_value)
+        continue;
+      if (val > value)
+        return i - 1;
+    }
+  }
+  return i-1;
+}
+
+
+/**
+  Perform context analysis of a BETWEEN item tree.
+
+    This function performs context analysis (name resolution) and calculates
+    various attributes of the item tree with Item_func_between as its root.
+    The function saves in ref the pointer to the item or to a newly created
+    item that is considered as a replacement for the original one.
+
+  @param thd     reference to the global context of the query thread
+  @param ref     pointer to Item* variable where pointer to resulting "fixed"
+                 item is to be assigned
+
+  @note
+    Let T0(e)/T1(e) be the value of not_null_tables(e) when e is used on
+    a predicate/function level. Then it's easy to show that:
+    @verbatim
+      T0(e BETWEEN e1 AND e2)     = union(T1(e),T1(e1),T1(e2))
+      T1(e BETWEEN e1 AND e2)     = union(T1(e),intersection(T1(e1),T1(e2)))
+      T0(e NOT BETWEEN e1 AND e2) = union(T1(e),intersection(T1(e1),T1(e2)))
+      T1(e NOT BETWEEN e1 AND e2) = union(T1(e),intersection(T1(e1),T1(e2)))
+    @endverbatim
+
+  @retval
+    0   ok
+  @retval
+    1   got error
+*/
+
+
+bool Item_func_between::eval_not_null_tables(void *opt_arg)
+{
+  if (Item_func_opt_neg::eval_not_null_tables(NULL))
+    return 1;
+
+  /* not_null_tables_cache == union(T1(e),T1(e1),T1(e2)) */
+  if (is_top_level_item() && !negated)
+    return 0;
+
+  /* not_null_tables_cache == union(T1(e), intersection(T1(e1),T1(e2))) */
+  not_null_tables_cache= (args[0]->not_null_tables() |
+                          (args[1]->not_null_tables() &
+                           args[2]->not_null_tables()));
+  return 0;
+}
+
+
+bool Item_func_between::find_not_null_fields(table_map allowed)
+{
+  if (negated || !is_top_level_item() || (~allowed & used_tables()))
+    return false;
+  return args[0]->find_not_null_fields(allowed) ||
+         args[1]->find_not_null_fields(allowed) ||
+         args[2]->find_not_null_fields(allowed);
+}
+
+
+bool Item_func_between::count_sargable_conds(void *arg)
+{
+  SELECT_LEX *sel= (SELECT_LEX *) arg;
+  sel->cond_count++;
+  sel->between_count++;
+  return 0;
+}
+
+
+void Item_func_between::fix_after_pullout(st_select_lex *new_parent,
+                                          Item **ref, bool merge)
+{
+  /* This will re-calculate attributes of the arguments */
+  Item_func_opt_neg::fix_after_pullout(new_parent, ref, merge);
+  /* Then, re-calculate not_null_tables_cache according to our special rules */
+  eval_not_null_tables(NULL);
+}
+
+bool Item_func_between::fix_length_and_dec(THD *thd)
+{
+  max_length= 1;
+
+  /*
+    As some compare functions are generated after sql_yacc,
+    we have to check for out of memory conditions here
+  */
+  if (!args[0] || !args[1] || !args[2])
+    return TRUE;
+  Item_args old_predicant(args[0]);
+  if (m_comparator.aggregate_for_comparison(Item_func_between::
+                                            func_name_cstring(),
+                                            args, 3, false))
+  {
+    DBUG_ASSERT(thd->is_error());
+    return TRUE;
+  }
+  if (m_comparator.type_handler()->Item_func_between_fix_length_and_dec(this))
+    return true;
+  raise_note_if_key_become_unused(thd, old_predicant);
+  return false;
+}
+
+
+bool Item_func_between::fix_length_and_dec_numeric(THD *thd)
+{
+  /* See the comment about the similar block in Item_bool_func2 */
+  if (args[0]->real_item()->type() == FIELD_ITEM &&
+      !thd->lex->is_ps_or_view_context_analysis())
+  {
+    Item_field *field_item= (Item_field*) (args[0]->real_item());
+    if (field_item->field_type() ==  MYSQL_TYPE_LONGLONG ||
+        field_item->field_type() ==  MYSQL_TYPE_YEAR)
+    {
+      const bool cvt_arg1= convert_const_to_int(thd, field_item, &args[1]);
+      const bool cvt_arg2= convert_const_to_int(thd, field_item, &args[2]);
+      if (cvt_arg1 && cvt_arg2)
+      {
+        // Works for all types
+        m_comparator.set_handler(&type_handler_slonglong);
+      }
+    }
+  }
+  return FALSE;
+}
+
+
+bool Item_func_between::fix_length_and_dec_temporal(THD *thd)
+{
+  if (!thd->lex->is_ps_or_view_context_analysis())
+  {
+    for (uint i= 0; i < 3; i ++)
+    {
+      if (args[i]->const_item() &&
+          args[i]->type_handler_for_comparison() != m_comparator.type_handler())
+      {
+        Item_cache *cache= m_comparator.type_handler()->Item_get_cache(thd, args[i]);
+        if (!cache || cache->setup(thd, args[i]))
+          return true;
+        thd->change_item_tree(&args[i], cache);
+      }
+    }
+  }
+  return false;
+}
+
+
+longlong Item_func_between::val_int_cmp_datetime()
+{
+  THD *thd= current_thd;
+  longlong value= args[0]->val_datetime_packed(thd), a, b;
+  if ((null_value= args[0]->null_value))
+    return 0;
+  a= args[1]->val_datetime_packed(thd);
+  b= args[2]->val_datetime_packed(thd);
+  return val_int_cmp_int_finalize(value, a, b);
+}
+
+
+longlong Item_func_between::val_int_cmp_time()
+{
+  THD *thd= current_thd;
+  longlong value= args[0]->val_time_packed(thd), a, b;
+  if ((null_value= args[0]->null_value))
+    return 0;
+  a= args[1]->val_time_packed(thd);
+  b= args[2]->val_time_packed(thd);
+  return val_int_cmp_int_finalize(value, a, b);
+}
+
+
+longlong Item_func_between::val_int_cmp_native()
+{
+  THD *thd= current_thd;
+  const Type_handler *h= m_comparator.type_handler();
+  NativeBuffer<STRING_BUFFER_USUAL_SIZE> value, a, b;
+  if (val_native_with_conversion_from_item(thd, args[0], &value, h))
+    return 0;
+  bool ra= args[1]->val_native_with_conversion(thd, &a, h);
+  bool rb= args[2]->val_native_with_conversion(thd, &b, h);
+  if (!ra && !rb)
+    return (longlong)
+      ((h->cmp_native(value, a) >= 0 &&
+        h->cmp_native(value, b) <= 0) != negated);
+  if (ra && rb)
+    null_value= true;
+  else if (ra)
+    null_value= h->cmp_native(value, b) <= 0;
+  else
+    null_value= h->cmp_native(value, a) >= 0;
+  return (longlong) (!null_value && negated);
+}
+
+
+longlong Item_func_between::val_int_cmp_string()
+{
+  String *value,*a,*b;
+  value=args[0]->val_str(&value0);
+  if ((null_value=args[0]->null_value))
+    return 0;
+  a= args[1]->val_str(&value1);
+  b= args[2]->val_str(&value2);
+  if (!args[1]->null_value && !args[2]->null_value)
+    return (longlong) ((sortcmp(value,a,cmp_collation.collation) >= 0 &&
+                        sortcmp(value,b,cmp_collation.collation) <= 0) !=
+                       negated);
+  if (args[1]->null_value && args[2]->null_value)
+    null_value= true;
+  else if (args[1]->null_value)
+  {
+    // Set to not null if false range.
+    null_value= sortcmp(value,b,cmp_collation.collation) <= 0;
+  }
+  else
+  {
+    // Set to not null if false range.
+    null_value= sortcmp(value,a,cmp_collation.collation) >= 0;
+  }
+  return (longlong) (!null_value && negated);
+}
+
+
+longlong Item_func_between::val_int_cmp_int()
+{
+  Longlong_hybrid value= args[0]->to_longlong_hybrid();
+  if ((null_value= args[0]->null_value))
+    return 0;					/* purecov: inspected */
+  Longlong_hybrid a= args[1]->to_longlong_hybrid();
+  Longlong_hybrid b= args[2]->to_longlong_hybrid();
+  if (!args[1]->null_value && !args[2]->null_value)
+    return (longlong) ((value.cmp(a) >= 0 && value.cmp(b) <= 0) != negated);
+  if (args[1]->null_value && args[2]->null_value)
+    null_value= true;
+  else if (args[1]->null_value)
+    null_value= value.cmp(b) <= 0;              // not null if false range.
+  else
+    null_value= value.cmp(a) >= 0;
+  return (longlong) (!null_value && negated);
+}
+
+
+bool Item_func_between::val_int_cmp_int_finalize(longlong value,
+                                                 longlong a,
+                                                 longlong b)
+{
+  if (!args[1]->null_value && !args[2]->null_value)
+    return (longlong) ((value >= a && value <= b) != negated);
+  if (args[1]->null_value && args[2]->null_value)
+    null_value= true;
+  else if (args[1]->null_value)
+    null_value= value <= b;			// not null if false range.
+  else
+    null_value= value >= a;
+  return (longlong) (!null_value && negated);
+}
+
+
+longlong Item_func_between::val_int_cmp_decimal()
+{
+  VDec dec(args[0]);
+  if ((null_value= dec.is_null()))
+    return 0;					/* purecov: inspected */
+  VDec a_dec(args[1]), b_dec(args[2]);
+  if (!a_dec.is_null() && !b_dec.is_null())
+    return (longlong) ((dec.cmp(a_dec) >= 0 &&
+                        dec.cmp(b_dec) <= 0) != negated);
+  if (a_dec.is_null() && b_dec.is_null())
+    null_value= true;
+  else if (a_dec.is_null())
+    null_value= (dec.cmp(b_dec) <= 0);
+  else
+    null_value= (dec.cmp(a_dec) >= 0);
+  return (longlong) (!null_value && negated);
+}
+
+
+longlong Item_func_between::val_int_cmp_real()
+{
+  double value= args[0]->val_real(),a,b;
+  if ((null_value=args[0]->null_value))
+    return 0;					/* purecov: inspected */
+  a= args[1]->val_real();
+  b= args[2]->val_real();
+  if (!args[1]->null_value && !args[2]->null_value)
+    return (longlong) ((value >= a && value <= b) != negated);
+  if (args[1]->null_value && args[2]->null_value)
+    null_value= true;
+  else if (args[1]->null_value)
+  {
+    null_value= value <= b;			// not null if false range.
+  }
+  else
+  {
+    null_value= value >= a;
+  }
+  return (longlong) (!null_value && negated);
+}
+
+
+void Item_func_between::print(String *str, enum_query_type query_type)
+{
+  args[0]->print_parenthesised(str, query_type, higher_precedence());
+  if (negated)
+    str->append(STRING_WITH_LEN(" not"));
+  str->append(STRING_WITH_LEN(" between "));
+  args[1]->print_parenthesised(str, query_type, precedence());
+  str->append(STRING_WITH_LEN(" and "));
+  args[2]->print_parenthesised(str, query_type, precedence());
+}
+
+
+double
+Item_func_ifnull::real_op()
+{
+  DBUG_ASSERT(fixed());
+  double value= args[0]->val_real();
+  if (!args[0]->null_value)
+  {
+    null_value=0;
+    return value;
+  }
+  value= args[1]->val_real();
+  if ((null_value=args[1]->null_value))
+    return 0.0;
+  return value;
+}
+
+longlong
+Item_func_ifnull::int_op()
+{
+  DBUG_ASSERT(fixed());
+  longlong value=args[0]->val_int();
+  if (!args[0]->null_value)
+  {
+    null_value=0;
+    return value;
+  }
+  value=args[1]->val_int();
+  if ((null_value=args[1]->null_value))
+    return 0;
+  return value;
+}
+
+
+my_decimal *Item_func_ifnull::decimal_op(my_decimal *decimal_value)
+{
+  DBUG_ASSERT(fixed());
+  my_decimal *value= args[0]->val_decimal(decimal_value);
+  if (!args[0]->null_value)
+  {
+    null_value= 0;
+    return value;
+  }
+  value= args[1]->val_decimal(decimal_value);
+  if ((null_value= args[1]->null_value))
+    return 0;
+  return value;
+}
+
+
+String *
+Item_func_ifnull::str_op(String *str)
+{
+  DBUG_ASSERT(fixed());
+  String *res  =args[0]->val_str(str);
+  if (!args[0]->null_value)
+  {
+    null_value=0;
+    res->set_charset(collation.collation);
+    return res;
+  }
+  res=args[1]->val_str(str);
+  if ((null_value=args[1]->null_value))
+    return 0;
+  res->set_charset(collation.collation);
+  return res;
+}
+
+
+bool Item_func_ifnull::native_op(THD *thd, Native *to)
+{
+  DBUG_ASSERT(fixed());
+  if (!val_native_with_conversion_from_item(thd, args[0], to, type_handler()))
+    return false;
+  return val_native_with_conversion_from_item(thd, args[1], to, type_handler());
+}
+
+
+bool Item_func_ifnull::date_op(THD *thd, MYSQL_TIME *ltime, date_mode_t fuzzydate)
+{
+  DBUG_ASSERT(fixed());
+  for (uint i= 0; i < 2; i++)
+  {
+    Datetime_truncation_not_needed dt(thd, args[i],
+                                      fuzzydate & ~TIME_FUZZY_DATES);
+    if (!(dt.copy_to_mysql_time(ltime, mysql_timestamp_type())))
+      return (null_value= false);
+  }
+  return (null_value= true);
+}
+
+
+bool Item_func_ifnull::time_op(THD *thd, MYSQL_TIME *ltime)
+{
+  DBUG_ASSERT(fixed());
+  for (uint i= 0; i < 2; i++)
+  {
+    if (!Time(thd, args[i]).copy_to_mysql_time(ltime))
+      return (null_value= false);
+  }
+  return (null_value= true);
+}
+
+
+/**
+  Perform context analysis of an IF item tree.
+
+    This function performs context analysis (name resolution) and calculates
+    various attributes of the item tree with Item_func_if as its root.
+    The function saves in ref the pointer to the item or to a newly created
+    item that is considered as a replacement for the original one.
+
+  @param thd     reference to the global context of the query thread
+  @param ref     pointer to Item* variable where pointer to resulting "fixed"
+                 item is to be assigned
+
+  @note
+    Let T0(e)/T1(e) be the value of not_null_tables(e) when e is used on
+    a predicate/function level. Then it's easy to show that:
+    @verbatim
+      T0(IF(e,e1,e2)  = T1(IF(e,e1,e2))
+      T1(IF(e,e1,e2)) = intersection(T1(e1),T1(e2))
+    @endverbatim
+
+  @retval
+    0   ok
+  @retval
+    1   got error
+*/
+
+bool
+Item_func_if::fix_fields(THD *thd, Item **ref)
+{
+  DBUG_ASSERT(fixed() == 0);
+  /*
+    Mark that we don't care if args[0] is NULL or FALSE, we regard both cases as
+    false.
+  */
+  args[0]->top_level_item();
+
+  if (Item_func::fix_fields(thd, ref))
+    return 1;
+
+  return 0;
+}
+
+
+bool
+Item_func_if::eval_not_null_tables(void *opt_arg)
+{
+  if (Item_func::eval_not_null_tables(NULL))
+    return 1;
+
+  not_null_tables_cache= (args[1]->not_null_tables() &
+                          args[2]->not_null_tables());
+
+  return 0;
+}
+
+
+void Item_func_if::fix_after_pullout(st_select_lex *new_parent,
+                                     Item **ref, bool merge)
+{
+  /* This will re-calculate attributes of the arguments */
+  Item_func::fix_after_pullout(new_parent, ref, merge);
+  /* Then, re-calculate not_null_tables_cache according to our special rules */
+  eval_not_null_tables(NULL);
+}
+
+
+void Item_func_nullif::split_sum_func(THD *thd, Ref_ptr_array ref_pointer_array,
+                                      List<Item> &fields, uint flags)
+{
+  if (m_cache)
+  {
+    flags|= SPLIT_SUM_SKIP_REGISTERED; // See Item_func::split_sum_func
+    m_cache->split_sum_func2_example(thd, ref_pointer_array, fields, flags);
+    args[1]->split_sum_func2(thd, ref_pointer_array, fields, &args[1], flags);
+  }
+  else
+  {
+    Item_func::split_sum_func(thd, ref_pointer_array, fields, flags);
+  }
+}
+
+
+bool Item_func_nullif::walk(Item_processor processor,
+                            bool walk_subquery, void *arg)
+{
+  /*
+    No needs to iterate through args[2] when it's just a copy of args[0].
+    See MDEV-9712 Performance degradation of nested NULLIF
+  */
+  uint tmp_count= arg_count == 2 || args[0] == args[2] ? 2 : 3;
+  for (uint i= 0; i < tmp_count; i++)
+  {
+    if (args[i]->walk(processor, walk_subquery, arg))
+      return true;
+  }
+  return (this->*processor)(arg);
+}
+
+
+void Item_func_nullif::update_used_tables()
+{
+  if (m_cache)
+  {
+    used_tables_and_const_cache_init();
+    used_tables_and_const_cache_update_and_join(m_cache->get_example());
+    used_tables_and_const_cache_update_and_join(arg_count, args);
+  }
+  else
+  {
+    /*
+      MDEV-9712 Performance degradation of nested NULLIF
+      No needs to iterate through args[2] when it's just a copy of args[0].
+    */
+    DBUG_ASSERT(arg_count == 3);
+    used_tables_and_const_cache_init();
+    used_tables_and_const_cache_update_and_join(args[0] == args[2] ? 2 : 3,
+                                                args);
+  }
+}
+
+
+
+bool
+Item_func_nullif::fix_length_and_dec(THD *thd)
+{
+  /*
+    If this is the first invocation of fix_length_and_dec(), create the
+    third argument as a copy of the first. This cannot be done before
+    fix_fields(), because fix_fields() might replace items,
+    for exampe NOT x --> x==0, or (SELECT 1) --> 1.
+    See also class Item_func_nullif declaration.
+  */
+  if (arg_count == 2)
+    args[arg_count++]= m_arg0 ? m_arg0 : args[0];
+
+  /*
+    At prepared statement EXECUTE time, args[0] can already
+    point to a different Item, created during PREPARE time fix_length_and_dec().
+    For example, if character set conversion was needed, arguments can look
+    like this:
+
+      args[0]= > Item_func_conv_charset \
+                                         l_expr
+      args[2]= >------------------------/
+
+    Otherwise (during PREPARE or convensional execution),
+    args[0] and args[2] should still point to the same original l_expr.
+  */
+  DBUG_ASSERT(args[0] == args[2] || thd->stmt_arena->is_stmt_execute());
+  if (args[0]->type() == SUM_FUNC_ITEM &&
+      !thd->lex->is_ps_or_view_context_analysis())
+  {
+    /*
+      NULLIF(l_expr, r_expr)
+
+        is calculated in the way to return a result equal to:
+
+      CASE WHEN l_expr = r_expr THEN NULL ELSE r_expr END.
+
+      There's nothing special with r_expr, because it's referenced
+      only by args[1] and nothing else.
+
+      l_expr needs a special treatment, as it's referenced by both
+      args[0] and args[2] initially.
+
+      args[2] is used to return the value. Afrer all transformations
+      (e.g. in fix_length_and_dec(), equal field propagation, etc)
+      args[2] points to a an Item which preserves the exact data type and
+      attributes (e.g. collation) of the original l_expr.
+      It can point:
+      - to the original l_expr
+      - to an Item_cache pointing to l_expr
+      - to a constant of the same data type with l_expr.
+
+      args[0] is used for comparison. It can be replaced:
+
+      - to Item_func_conv_charset by character set aggregation routines
+      - to a constant Item by equal field propagation routines
+        (in case of Item_field)
+
+      The data type and/or the attributes of args[0] can differ from
+      the data type and the attributes of the original l_expr, to make
+      it comparable to args[1] (which points to r_expr or its replacement).
+
+      For aggregate functions we have to wrap the original args[0]/args[2]
+      into Item_cache (see MDEV-9181). In this case the Item_cache
+      instance becomes the subject to character set conversion instead of
+      the original args[0]/args[2], while the original args[0]/args[2] get
+      hidden inside the cache.
+
+      Some examples of what NULLIF can end up with after argument
+      substitution (we don't mention args[1] in some cases for simplicity):
+
+      1. l_expr is not an aggregate function:
+
+        a. No conversion happened.
+           args[0] and args[2] were not replaced to something else
+           (i.e. neither by character set conversion, nor by propagation):
+
+          args[1] > r_expr
+          args[0] \
+                    l_expr
+          args[2] /
+
+        b. Conversion of args[0] happened:
+
+           CREATE OR REPLACE TABLE t1 (
+             a CHAR(10) CHARACTER SET latin1,
+             b CHAR(10) CHARACTER SET utf8);
+           SELECT * FROM t1 WHERE NULLIF(a,b);
+
+           args[1] > r_expr                          (Item_field for t1.b)
+           args[0] > Item_func_conv_charset\
+                                            l_expr   (Item_field for t1.a)
+           args[2] > ----------------------/
+
+        c. Conversion of args[1] happened:
+
+          CREATE OR REPLACE TABLE t1 (
+            a CHAR(10) CHARACTER SET utf8,
+            b CHAR(10) CHARACTER SET latin1);
+          SELECT * FROM t1 WHERE NULLIF(a,b);
+
+          args[1] > Item_func_conv_charset -> r_expr (Item_field for t1.b)
+          args[0] \
+                   l_expr                            (Item_field for t1.a)
+          args[2] /
+
+        d. Conversion of only args[0] happened (by equal field proparation):
+
+           CREATE OR REPLACE TABLE t1 (
+             a CHAR(10),
+             b CHAR(10));
+           SELECT * FROM t1 WHERE NULLIF(a,b) AND a='a';
+
+           args[1] > r_expr            (Item_field for t1.b)
+           args[0] > Item_string('a')  (constant replacement for t1.a)
+           args[2] > l_expr            (Item_field for t1.a)
+
+        e. Conversion of both args[0] and args[2] happened
+           (by equal field propagation):
+
+           CREATE OR REPLACE TABLE t1 (a INT,b INT);
+           SELECT * FROM t1 WHERE NULLIF(a,b) AND a=5;
+
+           args[1] > r_expr         (Item_field for "b")
+           args[0] \
+                    Item_int (5)    (constant replacement for "a")
+           args[2] /
+
+      2. In case if l_expr is an aggregate function:
+
+        a. No conversion happened:
+
+          args[0] \
+                   Item_cache > l_expr
+          args[2] /
+
+        b. Conversion of args[0] happened:
+
+          args[0] > Item_func_conv_charset \
+                                            Item_cache > l_expr
+          args[2] >------------------------/
+
+        c. Conversion of both args[0] and args[2] happened.
+           (e.g. by equal expression propagation)
+           TODO: check if it's possible (and add an example query if so).
+    */
+    m_cache= args[0]->cmp_type() == STRING_RESULT ?
+             new (thd->mem_root) Item_cache_str_for_nullif(thd, args[0]) :
+             args[0]->get_cache(thd);
+    if (!m_cache)
+      return TRUE;
+    m_cache->setup(thd, args[0]);
+    m_cache->store(args[0]);
+    m_cache->set_used_tables(args[0]->used_tables());
+    thd->change_item_tree(&args[0], m_cache);
+    thd->change_item_tree(&args[2], m_cache);
+  }
+  set_handler(args[2]->type_handler());
+  collation.set(args[2]->collation);
+  decimals= args[2]->decimals;
+  unsigned_flag= args[2]->unsigned_flag;
+  fix_char_length(args[2]->max_char_length());
+  set_maybe_null();
+  m_arg0= args[0];
+  if (setup_args_and_comparator(thd, &cmp))
+    return TRUE;
+  /*
+    A special code for EXECUTE..PREPARE.
+
+    If args[0] did not change, then we don't remember it, as it can point
+    to a temporary Item object which will be destroyed between PREPARE
+    and EXECUTE. EXECUTE time fix_length_and_dec() will correctly set args[2]
+    from args[0] again.
+
+    If args[0] changed, then it can be Item_func_conv_charset() for the
+    original args[0], which was permanently installed during PREPARE time
+    into the item tree as a wrapper for args[0], using change_item_tree(), i.e.
+
+      NULLIF(latin1_field, 'a' COLLATE utf8_bin)
+
+    was "rewritten" to:
+
+      CASE WHEN CONVERT(latin1_field USING utf8) = 'a' COLLATE utf8_bin
+        THEN NULL
+        ELSE latin1_field
+
+    - m_args0 points to Item_field corresponding to latin1_field
+    - args[0] points to Item_func_conv_charset
+    - args[0]->args[0] is equal to m_args0
+    - args[1] points to Item_func_set_collation
+    - args[2] points is eqial to m_args0
+
+    In this case we remember and reuse m_arg0 during EXECUTE time as args[2].
+
+    QQ: How to make sure that m_args0 does not point
+    to something temporary which will be destroyed between PREPARE and EXECUTE.
+    The condition below should probably be more strict and somehow check that:
+    - change_item_tree() was called for the new args[0]
+    - m_args0 is referenced from inside args[0], e.g. as a function argument,
+      and therefore it is also something that won't be destroyed between
+      PREPARE and EXECUTE.
+    Any ideas?
+  */
+  if (args[0] == m_arg0)
+    m_arg0= NULL;
+  return FALSE;
+}
+
+
+void Item_func_nullif::print(String *str, enum_query_type query_type)
+{
+  /*
+    NULLIF(a,b) is implemented according to the SQL standard as a short for
+    CASE WHEN a=b THEN NULL ELSE a END
+
+    The constructor of Item_func_nullif sets args[0] and args[2] to the
+    same item "a", and sets args[1] to "b".
+
+    If "this" is a part of a WHERE or ON condition, then:
+    - the left "a" is a subject to equal field propagation with ANY_SUBST.
+    - the right "a" is a subject to equal field propagation with IDENTITY_SUBST.
+    Therefore, after equal field propagation args[0] and args[2] can point
+    to different items.
+  */
+  if ((query_type & QT_ITEM_ORIGINAL_FUNC_NULLIF) ||
+      (arg_count == 2) ||
+      (args[0] == args[2]))
+  {
+    /*
+      If QT_ITEM_ORIGINAL_FUNC_NULLIF is requested,
+      that means we want the original NULLIF() representation,
+      e.g. when we are in:
+        SHOW CREATE {VIEW|FUNCTION|PROCEDURE}
+
+      The original representation is possible only if
+      args[0] and args[2] still point to the same Item.
+
+      The caller must never pass call print() with QT_ITEM_ORIGINAL_FUNC_NULLIF
+      if an expression has undergone some optimization
+      (e.g. equal field propagation done in optimize_cond()) already and
+      NULLIF() potentially has two different representations of "a":
+      - one "a" for comparison
+      - another "a" for the returned value!
+    */
+    DBUG_ASSERT(arg_count == 2 ||
+                args[0] == args[2] || current_thd->lex->context_analysis_only);
+    str->append(func_name_cstring());
+    str->append('(');
+    if (arg_count == 2)
+      args[0]->print(str, query_type);
+    else
+      args[2]->print(str, query_type);
+    str->append(',');
+    args[1]->print(str, query_type);
+    str->append(')');
+  }
+  else
+  {
+    /*
+      args[0] and args[2] are different items.
+      This is possible after WHERE optimization (equal fields propagation etc),
+      e.g. in EXPLAIN EXTENDED or EXPLAIN FORMAT=JSON.
+      As it's not possible to print as a function with 2 arguments any more,
+      do it in the CASE style.
+    */
+    str->append(STRING_WITH_LEN("(case when "));
+    args[0]->print(str, query_type);
+    str->append(STRING_WITH_LEN(" = "));
+    args[1]->print(str, query_type);
+    str->append(STRING_WITH_LEN(" then NULL else "));
+    args[2]->print(str, query_type);
+    str->append(STRING_WITH_LEN(" end)"));
+  }
+}
+
+
+int Item_func_nullif::compare()
+{
+  if (m_cache)
+    m_cache->cache_value();
+  return cmp.compare();
+}
+
+/**
+  @note
+  Note that we have to evaluate the first argument twice as the compare
+  may have been done with a different type than return value
+  @return
+    NULL  if arguments are equal
+  @return
+    the first argument if not equal
+*/
+
+double
+Item_func_nullif::real_op()
+{
+  DBUG_ASSERT(fixed());
+  double value;
+  if (!compare())
+  {
+    null_value=1;
+    return 0.0;
+  }
+  value= args[2]->val_real();
+  null_value= args[2]->null_value;
+  return value;
+}
+
+longlong
+Item_func_nullif::int_op()
+{
+  DBUG_ASSERT(fixed());
+  longlong value;
+  if (!compare())
+  {
+    null_value=1;
+    return 0;
+  }
+  value= args[2]->val_int();
+  null_value= args[2]->null_value;
+  return value;
+}
+
+String *
+Item_func_nullif::str_op(String *str)
+{
+  DBUG_ASSERT(fixed());
+  String *res;
+  if (!compare())
+  {
+    null_value=1;
+    return 0;
+  }
+  res= args[2]->val_str(str);
+  null_value= args[2]->null_value;
+  return res;
+}
+
+
+my_decimal *
+Item_func_nullif::decimal_op(my_decimal * decimal_value)
+{
+  DBUG_ASSERT(fixed());
+  my_decimal *res;
+  if (!compare())
+  {
+    null_value=1;
+    return 0;
+  }
+  res= args[2]->val_decimal(decimal_value);
+  null_value= args[2]->null_value;
+  return res;
+}
+
+
+bool
+Item_func_nullif::date_op(THD *thd, MYSQL_TIME *ltime, date_mode_t fuzzydate)
+{
+  DBUG_ASSERT(fixed());
+  if (!compare())
+    return (null_value= true);
+  Datetime_truncation_not_needed dt(thd, args[2], fuzzydate);
+  return (null_value= dt.copy_to_mysql_time(ltime, mysql_timestamp_type()));
+}
+
+
+bool
+Item_func_nullif::time_op(THD *thd, MYSQL_TIME *ltime)
+{
+  DBUG_ASSERT(fixed());
+  if (!compare())
+    return (null_value= true);
+  return (null_value= Time(thd, args[2]).copy_to_mysql_time(ltime));
+
+}
+
+
+bool
+Item_func_nullif::native_op(THD *thd, Native *to)
+{
+  DBUG_ASSERT(fixed());
+  if (!compare())
+    return (null_value= true);
+  return val_native_with_conversion_from_item(thd, args[2], to, type_handler());
+}
+
+
+bool
+Item_func_nullif::is_null()
+{
+  return (null_value= (!compare() ? 1 : args[2]->is_null()));
+}
+
+void Item_func_case::reorder_args(uint start)
+{
+  /*
+    Reorder args, to have at first the optional CASE expression, then all WHEN
+    expressions, then all THEN expressions. And the optional ELSE expression
+    at the end.
+
+    We reorder an even number of arguments, starting from start.
+  */
+  uint count = (arg_count - start) / 2;
+  const size_t size= sizeof(Item*) * count * 2;
+  Item **arg_buffer= (Item **)my_safe_alloca(size);
+  memcpy(arg_buffer, &args[start], size);
+  for (uint i= 0; i < count; i++)
+  {
+    args[start + i]= arg_buffer[i*2];
+    args[start + i + count]= arg_buffer[i*2 + 1];
+  }
+  my_safe_afree(arg_buffer, size);
+}
+
+
+
+/**
+    Find and return matching items for CASE or ELSE item if all compares
+    are failed or NULL if ELSE item isn't defined.
+
+  IMPLEMENTATION
+    In order to do correct comparisons of the CASE expression (the expression
+    between CASE and the first WHEN) with each WHEN expression several
+    comparators are used. One for each result type. CASE expression can be
+    evaluated up to # of different result types are used. To check whether
+    the CASE expression already was evaluated for a particular result type
+    a bit mapped variable value_added_map is used. Result types are mapped
+    to it according to their int values i.e. STRING_RESULT is mapped to bit
+    0, REAL_RESULT to bit 1, so on.
+
+  @retval
+    NULL  Nothing found and there is no ELSE expression defined
+  @retval
+    item  Found item or ELSE item if defined and all comparisons are
+           failed
+*/
+
+Item *Item_func_case_searched::find_item()
+{
+  uint count= when_count();
+  for (uint i= 0 ; i < count ; i++)
+  {
+    if (args[i]->val_bool())
+      return args[i + count];
+  }
+  Item **pos= Item_func_case_searched::else_expr_addr();
+  return pos ? pos[0] : 0;
+}
+
+
+Item *Item_func_case_simple::find_item()
+{
+  /* Compare every WHEN argument with it and return the first match */
+  uint idx;
+  if (!Predicant_to_list_comparator::cmp(this, &idx, NULL))
+    return args[idx + when_count()];
+  Item **pos= Item_func_case_simple::else_expr_addr();
+  return pos ? pos[0] : 0;
+}
+
+
+Item *Item_func_decode_oracle::find_item()
+{
+  uint idx;
+  if (!Predicant_to_list_comparator::cmp_nulls_equal(current_thd, this, &idx))
+    return args[idx + when_count()];
+  Item **pos= Item_func_decode_oracle::else_expr_addr();
+  return pos ? pos[0] : 0;
+}
+
+
+String *Item_func_case::str_op(String *str)
+{
+  DBUG_ASSERT(fixed());
+  String *res;
+  Item *item= find_item();
+
+  if (!item)
+  {
+    null_value=1;
+    return 0;
+  }
+  null_value= 0;
+  if (!(res=item->val_str(str)))
+    null_value= 1;
+  return res;
+}
+
+
+longlong Item_func_case::int_op()
+{
+  DBUG_ASSERT(fixed());
+  Item *item= find_item();
+  longlong res;
+
+  if (!item)
+  {
+    null_value=1;
+    return 0;
+  }
+  res=item->val_int();
+  null_value=item->null_value;
+  return res;
+}
+
+double Item_func_case::real_op()
+{
+  DBUG_ASSERT(fixed());
+  Item *item= find_item();
+  double res;
+
+  if (!item)
+  {
+    null_value=1;
+    return 0;
+  }
+  res= item->val_real();
+  null_value=item->null_value;
+  return res;
+}
+
+
+my_decimal *Item_func_case::decimal_op(my_decimal *decimal_value)
+{
+  DBUG_ASSERT(fixed());
+  Item *item= find_item();
+  my_decimal *res;
+
+  if (!item)
+  {
+    null_value=1;
+    return 0;
+  }
+
+  res= item->val_decimal(decimal_value);
+  null_value= item->null_value;
+  return res;
+}
+
+
+bool Item_func_case::date_op(THD *thd, MYSQL_TIME *ltime, date_mode_t fuzzydate)
+{
+  DBUG_ASSERT(fixed());
+  Item *item= find_item();
+  if (!item)
+    return (null_value= true);
+  Datetime_truncation_not_needed dt(thd, item, fuzzydate);
+  return (null_value= dt.copy_to_mysql_time(ltime, mysql_timestamp_type()));
+}
+
+
+bool Item_func_case::time_op(THD *thd, MYSQL_TIME *ltime)
+{
+  DBUG_ASSERT(fixed());
+  Item *item= find_item();
+  if (!item)
+    return (null_value= true);
+  return (null_value= Time(thd, item).copy_to_mysql_time(ltime));
+}
+
+
+bool Item_func_case::native_op(THD *thd, Native *to)
+{
+  DBUG_ASSERT(fixed());
+  Item *item= find_item();
+  if (!item)
+    return (null_value= true);
+  return val_native_with_conversion_from_item(thd, item, to, type_handler());
+}
+
+
+bool Item_func_case::fix_fields(THD *thd, Item **ref)
+{
+  bool res= Item_func::fix_fields(thd, ref);
+
+  Item **pos= else_expr_addr();
+  if (!pos || pos[0]->maybe_null())
+    set_maybe_null();
+  return res;
+}
+
+
+/**
+  Check if (*place) and new_value points to different Items and call
+  THD::change_item_tree() if needed.
+*/
+
+static void propagate_and_change_item_tree(THD *thd, Item **place,
+                                           COND_EQUAL *cond,
+                                           const Item::Context &ctx)
+{
+  Item *new_value= (*place)->propagate_equal_fields(thd, ctx, cond);
+  if (new_value && *place != new_value)
+    thd->change_item_tree(place, new_value);
+}
+
+
+bool Item_func_case_simple::prepare_predicant_and_values(THD *thd,
+                                                         uint *found_types,
+                                                         bool nulls_equal)
+{
+  bool have_null= false;
+  uint type_cnt;
+  Type_handler_hybrid_field_type tmp;
+  uint ncases= when_count();
+  add_predicant(this, 0);
+  for (uint i= 0 ; i < ncases; i++)
+  {
+    static LEX_CSTRING case_when= { STRING_WITH_LEN("case..when") };
+    if (nulls_equal ?
+        add_value(case_when, this, i + 1) :
+        add_value_skip_null(case_when, this, i + 1, &have_null))
+      return true;
+  }
+  all_values_added(&tmp, &type_cnt, &m_found_types);
+#ifndef DBUG_OFF
+  Predicant_to_list_comparator::debug_print(thd);
+#endif
+  return false;
+}
+
+
+bool Item_func_case_searched::fix_length_and_dec(THD *thd)
+{
+  return aggregate_then_and_else_arguments(thd, when_count());
+}
+
+
+bool Item_func_case_simple::fix_length_and_dec(THD *thd)
+{
+  return (aggregate_then_and_else_arguments(thd, when_count() + 1) ||
+          aggregate_switch_and_when_arguments(thd, false));
+}
+
+
+bool Item_func_decode_oracle::fix_length_and_dec(THD *thd)
+{
+  return (aggregate_then_and_else_arguments(thd, when_count() + 1) ||
+          aggregate_switch_and_when_arguments(thd, true));
+}
+
+
+/*
+  Aggregate all THEN and ELSE expression types
+  and collations when string result
+
+  @param THD       - current thd
+  @param start     - an element in args to start aggregating from
+*/
+bool Item_func_case::aggregate_then_and_else_arguments(THD *thd, uint start)
+{
+  if (aggregate_for_result(func_name_cstring(), args + start,
+                           arg_count - start, true))
+    return true;
+
+  if (fix_attributes(args + start, arg_count - start))
+    return true;
+
+  return false;
+}
+
+
+/*
+  Aggregate the predicant expression and all WHEN expression types
+  and collations when string comparison
+*/
+bool Item_func_case_simple::aggregate_switch_and_when_arguments(THD *thd,
+                                                                bool nulls_eq)
+{
+  uint ncases= when_count();
+  m_found_types= 0;
+  if (prepare_predicant_and_values(thd, &m_found_types, nulls_eq))
+  {
+    /*
+      If Predicant_to_list_comparator() fails to prepare components,
+      it must put an error into the diagnostics area. This is needed
+      to make fix_fields() catches such errors.
+    */
+    DBUG_ASSERT(thd->is_error());
+    return true;
+  }
+
+  if (!(m_found_types= collect_cmp_types(args, ncases + 1)))
+    return true;
+
+  if (m_found_types & (1U << STRING_RESULT))
+  {
+    /*
+      If we'll do string comparison, we also need to aggregate
+      character set and collation for first/WHEN items and
+      install converters for some of them to cmp_collation when necessary.
+      This is done because cmp_item compatators cannot compare
+      strings in two different character sets.
+      Some examples when we install converters:
+
+      1. Converter installed for the first expression:
+
+         CASE         latin1_item              WHEN utf16_item THEN ... END
+
+      is replaced to:
+
+         CASE CONVERT(latin1_item USING utf16) WHEN utf16_item THEN ... END
+
+      2. Converter installed for the left WHEN item:
+
+        CASE utf16_item WHEN         latin1_item              THEN ... END
+
+      is replaced to:
+
+         CASE utf16_item WHEN CONVERT(latin1_item USING utf16) THEN ... END
+    */
+    if (agg_arg_charsets_for_comparison(cmp_collation, args, ncases + 1))
+      return true;
+  }
+
+  if (make_unique_cmp_items(thd, cmp_collation.collation))
+    return true;
+
+  return false;
+}
+
+
+Item* Item_func_case_simple::propagate_equal_fields(THD *thd,
+                                                    const Context &ctx,
+                                                    COND_EQUAL *cond)
+{
+  const Type_handler *first_expr_cmp_handler;
+
+  first_expr_cmp_handler= args[0]->type_handler_for_comparison();
+  /*
+    Cannot replace the CASE (the switch) argument if
+    there are multiple comparison types were found, or found a single
+    comparison type that is not equal to args[0]->cmp_type().
+
+    - Example: multiple comparison types, can't propagate:
+        WHERE CASE str_column
+              WHEN 'string' THEN TRUE
+              WHEN 1 THEN TRUE
+              ELSE FALSE END;
+
+    - Example: a single incompatible comparison type, can't propagate:
+        WHERE CASE str_column
+              WHEN DATE'2001-01-01' THEN TRUE
+              ELSE FALSE END;
+
+    - Example: a single incompatible comparison type, can't propagate:
+        WHERE CASE str_column
+              WHEN 1 THEN TRUE
+              ELSE FALSE END;
+
+    - Example: a single compatible comparison type, ok to propagate:
+        WHERE CASE str_column
+              WHEN 'str1' THEN TRUE
+              WHEN 'str2' THEN TRUE
+              ELSE FALSE END;
+  */
+  if (m_found_types == (1UL << first_expr_cmp_handler->cmp_type()))
+    propagate_and_change_item_tree(thd, &args[0], cond,
+      Context(ANY_SUBST, first_expr_cmp_handler, cmp_collation.collation));
+
+  /*
+    These arguments are in comparison.
+    Allow invariants of the same value during propagation.
+    Note, as we pass ANY_SUBST, none of the WHEN arguments will be
+    replaced to zero-filled constants (only IDENTITY_SUBST allows this).
+    Such a change for WHEN arguments would require rebuilding cmp_items.
+  */
+  uint i, count= when_count();
+  for (i= 1; i <= count; i++)
+  {
+    Type_handler_hybrid_field_type tmp(first_expr_cmp_handler);
+    if (!tmp.aggregate_for_comparison(args[i]->type_handler_for_comparison()))
+      propagate_and_change_item_tree(thd, &args[i], cond,
+        Context(ANY_SUBST, tmp.type_handler(), cmp_collation.collation));
+  }
+
+  // THEN and ELSE arguments (they are not in comparison)
+  for (; i < arg_count; i++)
+    propagate_and_change_item_tree(thd, &args[i], cond, Context_identity());
+
+  return this;
+}
+
+
+inline void Item_func_case::print_when_then_arguments(String *str,
+                                                      enum_query_type
+                                                      query_type,
+                                                      Item **items, uint count)
+{
+  for (uint i= 0; i < count; i++)
+  {
+    str->append(STRING_WITH_LEN("when "));
+    items[i]->print(str, query_type);
+    str->append(STRING_WITH_LEN(" then "));
+    items[i + count]->print(str, query_type);
+    str->append(' ');
+  }
+}
+
+
+inline void Item_func_case::print_else_argument(String *str,
+                                                enum_query_type query_type,
+                                                Item *item)
+{
+  str->append(STRING_WITH_LEN("else "));
+  item->print(str, query_type);
+  str->append(' ');
+}
+
+
+void Item_func_case_searched::print(String *str, enum_query_type query_type)
+{
+  Item **pos;
+  str->append(STRING_WITH_LEN("case "));
+  print_when_then_arguments(str, query_type, &args[0], when_count());
+  if ((pos= Item_func_case_searched::else_expr_addr()))
+    print_else_argument(str, query_type, pos[0]);
+  str->append(STRING_WITH_LEN("end"));
+}
+
+
+void Item_func_case_simple::print(String *str, enum_query_type query_type)
+{
+  Item **pos;
+  str->append(STRING_WITH_LEN("case "));
+  args[0]->print_parenthesised(str, query_type, precedence());
+  str->append(' ');
+  print_when_then_arguments(str, query_type, &args[1], when_count());
+  if ((pos= Item_func_case_simple::else_expr_addr()))
+    print_else_argument(str, query_type, pos[0]);
+  str->append(STRING_WITH_LEN("end"));
+}
+
+
+void Item_func_decode_oracle::print(String *str, enum_query_type query_type)
+{
+  str->append(func_name_cstring());
+  str->append('(');
+  args[0]->print(str, query_type);
+  for (uint i= 1, count= when_count() ; i <= count; i++)
+  {
+    str->append(',');
+    args[i]->print(str, query_type);
+    str->append(',');
+    args[i+count]->print(str, query_type);
+  }
+  Item **else_expr= Item_func_case_simple::else_expr_addr();
+  if (else_expr)
+  {
+    str->append(',');
+    (*else_expr)->print(str, query_type);
+  }
+  str->append(')');
+}
+
+
+/**
+  Coalesce - return first not NULL argument.
+*/
+
+String *Item_func_coalesce::str_op(String *str)
+{
+  DBUG_ASSERT(fixed());
+  null_value=0;
+  for (uint i=0 ; i < arg_count ; i++)
+  {
+    String *res;
+    if ((res=args[i]->val_str(str)))
+      return res;
+  }
+  null_value=1;
+  return 0;
+}
+
+longlong Item_func_coalesce::int_op()
+{
+  DBUG_ASSERT(fixed());
+  null_value=0;
+  for (uint i=0 ; i < arg_count ; i++)
+  {
+    longlong res=args[i]->val_int();
+    if (!args[i]->null_value)
+      return res;
+  }
+  null_value=1;
+  return 0;
+}
+
+double Item_func_coalesce::real_op()
+{
+  DBUG_ASSERT(fixed());
+  null_value=0;
+  for (uint i=0 ; i < arg_count ; i++)
+  {
+    double res= args[i]->val_real();
+    if (!args[i]->null_value)
+      return res;
+  }
+  null_value=1;
+  return 0;
+}
+
+
+bool Item_func_coalesce::date_op(THD *thd, MYSQL_TIME *ltime, date_mode_t fuzzydate)
+{
+  DBUG_ASSERT(fixed());
+  for (uint i= 0; i < arg_count; i++)
+  {
+    Datetime_truncation_not_needed dt(thd, args[i],
+                                      fuzzydate & ~TIME_FUZZY_DATES);
+    if (!dt.copy_to_mysql_time(ltime, mysql_timestamp_type()))
+      return (null_value= false);
+  }
+  return (null_value= true);
+}
+
+
+bool Item_func_coalesce::time_op(THD *thd, MYSQL_TIME *ltime)
+{
+  DBUG_ASSERT(fixed());
+  for (uint i= 0; i < arg_count; i++)
+  {
+    if (!Time(thd, args[i]).copy_to_mysql_time(ltime))
+      return (null_value= false);
+  }
+  return (null_value= true);
+}
+
+
+bool Item_func_coalesce::native_op(THD *thd, Native *to)
+{
+  DBUG_ASSERT(fixed());
+  for (uint i= 0; i < arg_count; i++)
+  {
+    if (!val_native_with_conversion_from_item(thd, args[i], to, type_handler()))
+      return false;
+  }
+  return (null_value= true);
+}
+
+
+my_decimal *Item_func_coalesce::decimal_op(my_decimal *decimal_value)
+{
+  DBUG_ASSERT(fixed());
+  null_value= 0;
+  for (uint i= 0; i < arg_count; i++)
+  {
+    my_decimal *res= args[i]->val_decimal(decimal_value);
+    if (!args[i]->null_value)
+      return res;
+  }
+  null_value=1;
+  return 0;
+}
+
+
+/****************************************************************************
+ Classes and function for the IN operator
+****************************************************************************/
+
+/*
+  Determine which of the signed longlong arguments is bigger
+
+  SYNOPSIS
+    cmp_longs()
+      a_val     left argument
+      b_val     right argument
+
+  DESCRIPTION
+    This function will compare two signed longlong arguments
+    and will return -1, 0, or 1 if left argument is smaller than,
+    equal to or greater than the right argument.
+
+  RETURN VALUE
+    -1          left argument is smaller than the right argument.
+    0           left argument is equal to the right argument.
+    1           left argument is greater than the right argument.
+*/
+static inline int cmp_longs (longlong a_val, longlong b_val)
+{
+  return a_val < b_val ? -1 : a_val == b_val ? 0 : 1;
+}
+
+
+/*
+  Determine which of the unsigned longlong arguments is bigger
+
+  SYNOPSIS
+    cmp_ulongs()
+      a_val     left argument
+      b_val     right argument
+
+  DESCRIPTION
+    This function will compare two unsigned longlong arguments
+    and will return -1, 0, or 1 if left argument is smaller than,
+    equal to or greater than the right argument.
+
+  RETURN VALUE
+    -1          left argument is smaller than the right argument.
+    0           left argument is equal to the right argument.
+    1           left argument is greater than the right argument.
+*/
+static inline int cmp_ulongs (ulonglong a_val, ulonglong b_val)
+{
+  return a_val < b_val ? -1 : a_val == b_val ? 0 : 1;
+}
+
+
+/*
+  Compare two integers in IN value list format (packed_longlong) 
+
+  SYNOPSIS
+    cmp_longlong()
+      cmp_arg   an argument passed to the calling function (my_qsort2)
+      a         left argument
+      b         right argument
+
+  DESCRIPTION
+    This function will compare two integer arguments in the IN value list
+    format and will return -1, 0, or 1 if left argument is smaller than,
+    equal to or greater than the right argument.
+    It's used in sorting the IN values list and finding an element in it.
+    Depending on the signedness of the arguments cmp_longlong() will
+    compare them as either signed (using cmp_longs()) or unsigned (using
+    cmp_ulongs()).
+
+  RETURN VALUE
+    -1          left argument is smaller than the right argument.
+    0           left argument is equal to the right argument.
+    1           left argument is greater than the right argument.
+*/
+int cmp_longlong(void *cmp_arg, 
+                 in_longlong::packed_longlong *a,
+                 in_longlong::packed_longlong *b)
+{
+  if (a->unsigned_flag != b->unsigned_flag)
+  { 
+    /* 
+      One of the args is unsigned and is too big to fit into the 
+      positive signed range. Report no match.
+    */  
+    if ((a->unsigned_flag && ((ulonglong) a->val) > (ulonglong) LONGLONG_MAX)
+        ||
+        (b->unsigned_flag && ((ulonglong) b->val) > (ulonglong) LONGLONG_MAX))
+      return a->unsigned_flag ? 1 : -1;
+    /*
+      Although the signedness differs both args can fit into the signed 
+      positive range. Make them signed and compare as usual.
+    */  
+    return cmp_longs(a->val, b->val);
+  }
+  if (a->unsigned_flag)
+    return cmp_ulongs((ulonglong) a->val, (ulonglong) b->val);
+  return cmp_longs(a->val, b->val);
+}
+
+static int cmp_double(void *cmp_arg, double *a,double *b)
+{
+  return *a < *b ? -1 : *a == *b ? 0 : 1;
+}
+
+static int cmp_row(void *cmp_arg, cmp_item_row *a, cmp_item_row *b)
+{
+  return a->compare(b);
+}
+
+
+static int cmp_decimal(void *cmp_arg, my_decimal *a, my_decimal *b)
+{
+  /*
+    We need call of fixing buffer pointer, because fast sort just copy
+    decimal buffers in memory and pointers left pointing on old buffer place
+  */
+  a->fix_buffer_pointer();
+  b->fix_buffer_pointer();
+  return my_decimal_cmp(a, b);
+}
+
+
+bool in_vector::find(Item *item)
+{
+  uchar *result=get_value(item);
+  if (!result || !used_count)
+    return false;				// Null value
+
+  uint start,end;
+  start=0; end=used_count-1;
+  while (start != end)
+  {
+    uint mid=(start+end+1)/2;
+    int res;
+    if ((res=(*compare)(collation, base+mid*size, result)) == 0)
+      return true;
+    if (res < 0)
+      start=mid;
+    else
+      end=mid-1;
+  }
+  return ((*compare)(collation, base+start*size, result) == 0);
+}
+
+in_string::in_string(THD *thd, uint elements, qsort2_cmp cmp_func,
+                     CHARSET_INFO *cs)
+  :in_vector(thd, elements, sizeof(String), cmp_func, cs),
+   tmp(buff, sizeof(buff), &my_charset_bin)
+{}
+
+in_string::~in_string()
+{
+  if (base)
+  {
+    // base was allocated on THD::mem_root => following is OK
+    for (uint i=0 ; i < count ; i++)
+      ((String*) base)[i].free();
+  }
+}
+
+bool in_string::set(uint pos, Item *item)
+{
+  String *str=((String*) base)+pos;
+  String *res=item->val_str(str);
+  if (res && res != str)
+  {
+    if (res->uses_buffer_owned_by(str))
+      res->copy();
+    if (item->type() == Item::FUNC_ITEM)
+      str->copy(*res);
+    else
+      *str= *res;
+  }
+  if (!str->charset())
+  {
+    CHARSET_INFO *cs;
+    if (!(cs= item->collation.collation))
+      cs= &my_charset_bin;		// Should never happen for STR items
+    str->set_charset(cs);
+  }
+  return res == NULL;
+}
+
+
+uchar *in_string::get_value(Item *item)
+{
+  return (uchar*) item->val_str(&tmp);
+}
+
+Item *in_string::create_item(THD *thd)
+{
+  return new (thd->mem_root) Item_string_for_in_vector(thd, collation);
+}
+
+
+in_row::in_row(THD *thd, uint elements, Item * item)
+{
+  base= (char*) new (thd->mem_root) cmp_item_row[count= elements];
+  size= sizeof(cmp_item_row);
+  compare= (qsort2_cmp) cmp_row;
+  /*
+    We need to reset these as otherwise we will call sort() with
+    uninitialized (even if not used) elements
+  */
+  used_count= elements;
+  collation= 0;
+}
+
+in_row::~in_row()
+{
+  if (base)
+    delete [] (cmp_item_row*) base;
+}
+
+uchar *in_row::get_value(Item *item)
+{
+  tmp.store_value(item);
+  if (item->is_null())
+    return 0;
+  return (uchar *)&tmp;
+}
+
+bool in_row::set(uint pos, Item *item)
+{
+  DBUG_ENTER("in_row::set");
+  DBUG_PRINT("enter", ("pos: %u  item: %p", pos,item));
+  DBUG_RETURN(((cmp_item_row*) base)[pos].store_value_by_template(current_thd,
+                                                                  &tmp, item));
+}
+
+in_longlong::in_longlong(THD *thd, uint elements)
+  :in_vector(thd, elements, sizeof(packed_longlong),
+             (qsort2_cmp) cmp_longlong, 0)
+{}
+
+bool in_longlong::set(uint pos, Item *item)
+{
+  struct packed_longlong *buff= &((packed_longlong*) base)[pos];
+  
+  buff->val= item->val_int();
+  buff->unsigned_flag= item->unsigned_flag;
+  return item->null_value;
+}
+
+uchar *in_longlong::get_value(Item *item)
+{
+  tmp.val= item->val_int();
+  if (item->null_value)
+    return 0;
+  tmp.unsigned_flag= item->unsigned_flag;
+  return (uchar*) &tmp;
+}
+
+Item *in_longlong::create_item(THD *thd)
+{ 
+  /* 
+     We're created a signed INT, this may not be correct in 
+     general case (see BUG#19342).
+  */
+  return new (thd->mem_root) Item_int(thd, (longlong)0);
+}
+
+
+static int cmp_timestamp(void *cmp_arg,
+                         Timestamp_or_zero_datetime *a,
+                         Timestamp_or_zero_datetime *b)
+{
+  return a->cmp(*b);
+}
+
+
+in_timestamp::in_timestamp(THD *thd, uint elements)
+  :in_vector(thd, elements, sizeof(Value), (qsort2_cmp) cmp_timestamp, 0)
+{}
+
+
+bool in_timestamp::set(uint pos, Item *item)
+{
+  Timestamp_or_zero_datetime *buff= &((Timestamp_or_zero_datetime *) base)[pos];
+  Timestamp_or_zero_datetime_native_null native(current_thd, item, true);
+  if (native.is_null())
+  {
+    *buff= Timestamp_or_zero_datetime();
+    return true;
+  }
+  *buff= Timestamp_or_zero_datetime(native);
+  return false;
+}
+
+
+uchar *in_timestamp::get_value(Item *item)
+{
+  Timestamp_or_zero_datetime_native_null native(current_thd, item, true);
+  if (native.is_null())
+    return 0;
+  tmp= Timestamp_or_zero_datetime(native);
+  return (uchar*) &tmp;
+}
+
+
+Item *in_timestamp::create_item(THD *thd)
+{
+  return new (thd->mem_root) Item_timestamp_literal(thd);
+}
+
+
+void in_timestamp::value_to_item(uint pos, Item *item)
+{
+  const Timestamp_or_zero_datetime &buff= (((Timestamp_or_zero_datetime*) base)[pos]);
+  static_cast<Item_timestamp_literal*>(item)->set_value(buff);
+}
+
+
+bool in_datetime::set(uint pos, Item *item)
+{
+  struct packed_longlong *buff= &((packed_longlong*) base)[pos];
+
+  buff->val= item->val_datetime_packed(current_thd);
+  buff->unsigned_flag= 1L;
+  return item->null_value;
+}
+
+bool in_time::set(uint pos, Item *item)
+{
+  struct packed_longlong *buff= &((packed_longlong*) base)[pos];
+
+  buff->val= item->val_time_packed(current_thd);
+  buff->unsigned_flag= 1L;
+  return item->null_value;
+}
+
+uchar *in_datetime::get_value(Item *item)
+{
+  tmp.val= item->val_datetime_packed(current_thd);
+  if (item->null_value)
+    return 0;
+  tmp.unsigned_flag= 1L;
+  return (uchar*) &tmp;
+}
+
+uchar *in_time::get_value(Item *item)
+{
+  tmp.val= item->val_time_packed(current_thd);
+  if (item->null_value)
+    return 0;
+  tmp.unsigned_flag= 1L;
+  return (uchar*) &tmp;
+}
+
+Item *in_temporal::create_item(THD *thd)
+{ 
+  return new (thd->mem_root) Item_datetime(thd);
+}
+
+
+in_double::in_double(THD *thd, uint elements)
+  :in_vector(thd, elements, sizeof(double), (qsort2_cmp) cmp_double, 0)
+{}
+
+bool in_double::set(uint pos, Item *item)
+{
+  ((double*) base)[pos]= item->val_real();
+  return item->null_value;
+}
+
+uchar *in_double::get_value(Item *item)
+{
+  tmp= item->val_real();
+  if (item->null_value)
+    return 0;					/* purecov: inspected */
+  return (uchar*) &tmp;
+}
+
+Item *in_double::create_item(THD *thd)
+{ 
+  return new (thd->mem_root) Item_float(thd, 0.0, 0);
+}
+
+
+in_decimal::in_decimal(THD *thd, uint elements)
+  :in_vector(thd, elements, sizeof(my_decimal), (qsort2_cmp) cmp_decimal, 0)
+{}
+
+
+bool in_decimal::set(uint pos, Item *item)
+{
+  /* as far as 'item' is constant, we can store reference on my_decimal */
+  my_decimal *dec= ((my_decimal *)base) + pos;
+  dec->len= DECIMAL_BUFF_LENGTH;
+  dec->fix_buffer_pointer();
+  my_decimal *res= item->val_decimal(dec);
+  /* if item->val_decimal() is evaluated to NULL then res == 0 */ 
+  if (!item->null_value && res != dec)
+    my_decimal2decimal(res, dec);
+  return item->null_value;
+}
+
+
+uchar *in_decimal::get_value(Item *item)
+{
+  my_decimal *result= item->val_decimal(&val);
+  if (item->null_value)
+    return 0;
+  return (uchar *)result;
+}
+
+Item *in_decimal::create_item(THD *thd)
+{ 
+  return new (thd->mem_root) Item_decimal(thd, 0, FALSE);
+}
+
+
+bool Predicant_to_list_comparator::alloc_comparators(THD *thd, uint nargs)
+{
+  size_t nbytes= sizeof(Predicant_to_value_comparator) * nargs;
+  if (!(m_comparators= (Predicant_to_value_comparator *) thd->alloc(nbytes)))
+    return true;
+  memset(m_comparators, 0, nbytes);
+  return false;
+}
+
+
+bool Predicant_to_list_comparator::add_value(const LEX_CSTRING &funcname,
+                                             Item_args *args,
+                                             uint value_index)
+{
+  DBUG_ASSERT(m_predicant_index < args->argument_count());
+  DBUG_ASSERT(value_index < args->argument_count());
+  Type_handler_hybrid_field_type tmp;
+  Item *tmpargs[2];
+  tmpargs[0]= args->arguments()[m_predicant_index];
+  tmpargs[1]= args->arguments()[value_index];
+  if (tmp.aggregate_for_comparison(funcname, tmpargs, 2, true))
+  {
+    DBUG_ASSERT(current_thd->is_error());
+    return true;
+  }
+  m_comparators[m_comparator_count].m_handler= tmp.type_handler();
+  m_comparators[m_comparator_count].m_arg_index= value_index;
+  m_comparator_count++;
+  return false;
+}
+
+
+bool Predicant_to_list_comparator::
+add_value_skip_null(const LEX_CSTRING &funcname,
+                    Item_args *args,
+                    uint value_index,
+                    bool *nulls_found)
+{
+  /*
+    Skip explicit NULL constant items.
+    Using real_item() to correctly detect references to explicit NULLs
+    in HAVING clause, e.g. in this example "b" is skipped:
+      SELECT a,NULL AS b FROM t1 GROUP BY a HAVING 'A' IN (b,'A');
+  */
+  if (args->arguments()[value_index]->real_item()->type() == Item::NULL_ITEM)
+  {
+    *nulls_found= true;
+    return false;
+  }
+  return add_value(funcname, args, value_index);
+}
+
+
+void Predicant_to_list_comparator::
+       detect_unique_handlers(Type_handler_hybrid_field_type *compatible,
+                              uint *unique_count,
+                              uint *found_types)
+{
+  *unique_count= 0;
+  *found_types= 0;
+  for (uint i= 0; i < m_comparator_count; i++)
+  {
+    uint idx;
+    if (find_handler(&idx, m_comparators[i].m_handler, i))
+    {
+      m_comparators[i].m_handler_index= i; // New unique handler
+      (*unique_count)++;
+      (*found_types)|= 1U << m_comparators[i].m_handler->cmp_type();
+      compatible->set_handler(m_comparators[i].m_handler);
+    }
+    else
+    {
+      m_comparators[i].m_handler_index= idx; // Non-unique handler
+    }
+  }
+}
+
+
+bool Predicant_to_list_comparator::make_unique_cmp_items(THD *thd,
+                                                         CHARSET_INFO *cs)
+{
+  for (uint i= 0; i < m_comparator_count; i++)
+  {
+    if (m_comparators[i].m_handler &&                   // Skip implicit NULLs
+        m_comparators[i].m_handler_index == i && // Skip non-unuque
+        !(m_comparators[i].m_cmp_item=
+          m_comparators[i].m_handler->make_cmp_item(thd, cs)))
+       return true;
+  }
+  return false;
+}
+
+
+cmp_item* cmp_item_sort_string::make_same(THD *thd)
+{
+  return new (thd->mem_root) cmp_item_sort_string_in_static(cmp_charset);
+}
+
+cmp_item* cmp_item_int::make_same(THD *thd)
+{
+  return new (thd->mem_root) cmp_item_int();
+}
+
+cmp_item* cmp_item_real::make_same(THD *thd)
+{
+  return new (thd->mem_root) cmp_item_real();
+}
+
+cmp_item* cmp_item_row::make_same(THD *thd)
+{
+  return new (thd->mem_root) cmp_item_row();
+}
+
+
+cmp_item_row::~cmp_item_row()
+{
+  DBUG_ENTER("~cmp_item_row");
+  DBUG_PRINT("enter",("this: %p", this));
+  if (comparators)
+  {
+    for (uint i= 0; i < n; i++)
+    {
+      if (comparators[i])
+	delete comparators[i];
+    }
+  }
+  DBUG_VOID_RETURN;
+}
+
+
+bool cmp_item_row::alloc_comparators(THD *thd, uint cols)
+{
+  if (comparators)
+  {
+    DBUG_ASSERT(cols == n);
+    return false;
+  }
+  return
+    !(comparators= (cmp_item **) thd->calloc(sizeof(cmp_item *) * (n= cols)));
+}
+
+
+void cmp_item_row::store_value(Item *item)
+{
+  DBUG_ENTER("cmp_item_row::store_value");
+  DBUG_ASSERT(comparators);
+  DBUG_ASSERT(n == item->cols());
+  item->bring_value();
+  item->null_value= 0;
+  for (uint i=0; i < n; i++)
+  {
+    DBUG_ASSERT(comparators[i]);
+    comparators[i]->store_value(item->element_index(i));
+    item->null_value|= item->element_index(i)->null_value;
+  }
+  DBUG_VOID_RETURN;
+}
+
+
+bool cmp_item_row::store_value_by_template(THD *thd, cmp_item *t, Item *item)
+{
+  cmp_item_row *tmpl= (cmp_item_row*) t;
+  if (tmpl->n != item->cols())
+  {
+    my_error(ER_OPERAND_COLUMNS, MYF(0), tmpl->n);
+    return 1;
+  }
+  n= tmpl->n;
+  bool rc= false;
+  if ((comparators= (cmp_item **) thd->alloc(sizeof(cmp_item *)*n)))
+  {
+    item->bring_value();
+    item->null_value= 0;
+    for (uint i=0; i < n; i++)
+    {
+      if (!(comparators[i]= tmpl->comparators[i]->make_same(thd)))
+	break;					// new failed
+      rc|= comparators[i]->store_value_by_template(thd, tmpl->comparators[i],
+                                                   item->element_index(i));
+    }
+  }
+  return rc;
+}
+
+
+int cmp_item_row::cmp(Item *arg)
+{
+  arg->null_value= 0;
+  if (arg->cols() != n)
+  {
+    my_error(ER_OPERAND_COLUMNS, MYF(0), n);
+    return 1;
+  }
+  bool was_null= 0;
+  arg->bring_value();
+  for (uint i=0; i < n; i++)
+  {
+    const int rc= comparators[i]->cmp(arg->element_index(i));
+    switch (rc)
+    {
+    case UNKNOWN:
+      was_null= true;
+      break;
+    case TRUE:
+      return TRUE;
+    case FALSE:
+      break;                                    // elements #i are equal
+    }
+    arg->null_value|= arg->element_index(i)->null_value;
+  }
+  return was_null ? UNKNOWN : FALSE;
+}
+
+
+int cmp_item_row::compare(cmp_item *c)
+{
+  cmp_item_row *l_cmp= (cmp_item_row *) c;
+  for (uint i=0; i < n; i++)
+  {
+    int res;
+    if ((res= comparators[i]->compare(l_cmp->comparators[i])))
+      return res;
+  }
+  return 0;
+}
+
+
+void cmp_item_decimal::store_value(Item *item)
+{
+  my_decimal *val= item->val_decimal(&value);
+  /* val may be zero if item is nnull */
+  if (val && val != &value)
+    my_decimal2decimal(val, &value);
+  m_null_value= item->null_value;
+}
+
+
+int cmp_item_decimal::cmp_not_null(const Value *val)
+{
+  DBUG_ASSERT(!val->is_null());
+  DBUG_ASSERT(val->is_decimal());
+  return my_decimal_cmp(&value, &val->m_decimal);
+}
+
+
+int cmp_item_decimal::cmp(Item *arg)
+{
+  VDec tmp(arg);
+  return m_null_value || tmp.is_null() ? UNKNOWN : (tmp.cmp(&value) != 0);
+}
+
+
+int cmp_item_decimal::compare(cmp_item *arg)
+{
+  cmp_item_decimal *l_cmp= (cmp_item_decimal*) arg;
+  return my_decimal_cmp(&value, &l_cmp->value);
+}
+
+
+cmp_item* cmp_item_decimal::make_same(THD *thd)
+{
+  return new (thd->mem_root) cmp_item_decimal();
+}
+
+
+int cmp_item_datetime::cmp_not_null(const Value *val)
+{
+  DBUG_ASSERT(!val->is_null());
+  DBUG_ASSERT(val->is_temporal());
+  return value != pack_time(&val->value.m_time);
+}
+
+
+int cmp_item_datetime::cmp(Item *arg)
+{
+  const bool rc= value != arg->val_datetime_packed(current_thd);
+  return (m_null_value || arg->null_value) ? UNKNOWN : rc;
+}
+
+
+int cmp_item_time::cmp_not_null(const Value *val)
+{
+  DBUG_ASSERT(!val->is_null());
+  DBUG_ASSERT(val->is_temporal());
+  return value != pack_time(&val->value.m_time);
+}
+
+
+int cmp_item_time::cmp(Item *arg)
+{
+  const bool rc= value != arg->val_time_packed(current_thd);
+  return (m_null_value || arg->null_value) ? UNKNOWN : rc;
+}
+
+
+int cmp_item_temporal::compare(cmp_item *ci)
+{
+  cmp_item_temporal *l_cmp= (cmp_item_temporal *)ci;
+  return (value < l_cmp->value) ? -1 : ((value == l_cmp->value) ? 0 : 1);
+}
+
+
+cmp_item *cmp_item_datetime::make_same(THD *thd)
+{
+  return new (thd->mem_root) cmp_item_datetime();
+}
+
+
+cmp_item *cmp_item_time::make_same(THD *thd)
+{
+  return new (thd->mem_root) cmp_item_time();
+}
+
+
+void cmp_item_timestamp::store_value(Item *item)
+{
+  item->val_native_with_conversion(current_thd, &m_native,
+                                   &type_handler_timestamp2);
+  m_null_value= item->null_value;
+}
+
+
+int cmp_item_timestamp::cmp_not_null(const Value *val)
+{
+  /*
+    This method will be implemented when we add this syntax:
+      SELECT TIMESTAMP WITH LOCAL TIME ZONE '2001-01-01 10:20:30'
+    For now TIMESTAMP is compared to non-TIMESTAMP using DATETIME.
+  */
+  DBUG_ASSERT(0);
+  return 0;
+}
+
+
+int cmp_item_timestamp::cmp(Item *arg)
+{
+  THD *thd= current_thd;
+  Timestamp_or_zero_datetime_native_null tmp(thd, arg, true);
+  return m_null_value || tmp.is_null() ? UNKNOWN :
+         type_handler_timestamp2.cmp_native(m_native, tmp) != 0;
+}
+
+
+int cmp_item_timestamp::compare(cmp_item *arg)
+{
+  cmp_item_timestamp *tmp= static_cast<cmp_item_timestamp*>(arg);
+  return type_handler_timestamp2.cmp_native(m_native, tmp->m_native);
+}
+
+
+cmp_item* cmp_item_timestamp::make_same(THD *thd)
+{
+  return new (thd->mem_root) cmp_item_timestamp();
+}
+
+
+
+bool Item_func_in::count_sargable_conds(void *arg)
+{
+  ((SELECT_LEX*) arg)->cond_count++;
+  return 0;
+}
+
+
+bool Item_func_in::list_contains_null()
+{
+  Item **arg,**arg_end;
+  for (arg= args + 1, arg_end= args+arg_count; arg != arg_end ; arg++)
+  {
+    if ((*arg)->null_inside())
+      return 1;
+  }
+  return 0;
+}
+
+
+/**
+  Perform context analysis of an IN item tree.
+
+    This function performs context analysis (name resolution) and calculates
+    various attributes of the item tree with Item_func_in as its root.
+    The function saves in ref the pointer to the item or to a newly created
+    item that is considered as a replacement for the original one.
+
+  @param thd     reference to the global context of the query thread
+  @param ref     pointer to Item* variable where pointer to resulting "fixed"
+                 item is to be assigned
+
+  @note
+    Let T0(e)/T1(e) be the value of not_null_tables(e) when e is used on
+    a predicate/function level. Then it's easy to show that:
+    @verbatim
+      T0(e IN(e1,...,en))     = union(T1(e),intersection(T1(ei)))
+      T1(e IN(e1,...,en))     = union(T1(e),intersection(T1(ei)))
+      T0(e NOT IN(e1,...,en)) = union(T1(e),union(T1(ei)))
+      T1(e NOT IN(e1,...,en)) = union(T1(e),intersection(T1(ei)))
+    @endverbatim
+
+  @retval
+    0   ok
+  @retval
+    1   got error
+*/
+
+bool
+Item_func_in::fix_fields(THD *thd, Item **ref)
+{
+
+  if (Item_func_opt_neg::fix_fields(thd, ref))
+    return 1;
+
+  return 0;
+}
+
+
+Item *Item_func_in::in_predicate_to_equality_transformer(THD *thd, uchar *arg)
+{
+  if (!array || have_null || !all_items_are_consts(args + 1, arg_count - 1))
+    return this; /* Transformation is not applicable */
+
+  /*
+    If all elements in the array of constant values are equal and there are
+    no NULLs in the list then clause
+    -  "a IN (e1,..,en)" can be converted to "a = e1"
+    -  "a NOT IN (e1,..,en)" can be converted to "a != e1".
+    This means an object of Item_func_in can be replaced with an object of
+    Item_func_eq for IN (e1,..,en) clause or Item_func_ne for
+    NOT IN (e1,...,en).
+  */
+
+  /*
+    Since the array is sorted it's enough to compare the first and the last
+    elements to tell whether all elements are equal
+  */
+  if (array->compare_elems(0, array->used_count - 1))
+  {
+    /* Not all elements are equal, transformation is not possible */
+    return this;
+  }
+
+  Json_writer_object trace_wrapper(thd);
+  trace_wrapper.add("transformation", "in_predicate_to_equality")
+               .add("before", this);
+
+  Item *new_item= nullptr;
+  if (negated)
+    new_item= new (thd->mem_root) Item_func_ne(thd, args[0], args[1]);
+  else
+    new_item= new (thd->mem_root) Item_func_eq(thd, args[0], args[1]);
+  if (new_item)
+  {
+    new_item->set_name(thd, name);
+    if (new_item->fix_fields(thd, &new_item))
+    {
+      /*
+        If there are any problems during fixing fields, there is no need to
+        return an error, just discard the transformation
+      */
+      new_item= this;
+    }
+  }
+  trace_wrapper.add("after", new_item);
+  return new_item;
+}
+
+bool
+Item_func_in::eval_not_null_tables(void *opt_arg)
+{
+  Item **arg, **arg_end;
+
+  if (Item_func_opt_neg::eval_not_null_tables(NULL))
+    return 1;
+
+  /* not_null_tables_cache == union(T1(e),union(T1(ei))) */
+  if (is_top_level_item() && negated)
+    return 0;
+
+  /* not_null_tables_cache = union(T1(e),intersection(T1(ei))) */
+  not_null_tables_cache= ~(table_map) 0;
+  for (arg= args + 1, arg_end= args + arg_count; arg != arg_end; arg++)
+    not_null_tables_cache&= (*arg)->not_null_tables();
+  not_null_tables_cache|= (*args)->not_null_tables();
+  return 0;
+}
+
+
+bool
+Item_func_in::find_not_null_fields(table_map allowed)
+{
+  if (negated || !is_top_level_item() || (~allowed & used_tables()))
+    return 0;
+  return  args[0]->find_not_null_fields(allowed);
+}
+
+
+void Item_func_in::fix_after_pullout(st_select_lex *new_parent, Item **ref,
+                                     bool merge)
+{
+  /* This will re-calculate attributes of the arguments */
+  Item_func_opt_neg::fix_after_pullout(new_parent, ref, merge);
+  /* Then, re-calculate not_null_tables_cache according to our special rules */
+  eval_not_null_tables(NULL);
+}
+
+
+bool Item_func_in::prepare_predicant_and_values(THD *thd, uint *found_types)
+{
+  uint type_cnt;
+  have_null= false;
+
+  add_predicant(this, 0);
+  for (uint i= 1 ; i < arg_count; i++)
+  {
+    if (add_value_skip_null(Item_func_in::func_name_cstring(), this, i,
+                            &have_null))
+      return true;
+  }
+  all_values_added(&m_comparator, &type_cnt, found_types);
+  arg_types_compatible= type_cnt < 2;
+
+#ifndef DBUG_OFF
+  Predicant_to_list_comparator::debug_print(thd);
+#endif
+  return false;
+}
+
+
+bool Item_func_in::fix_length_and_dec(THD *thd)
+{
+  Item_args old_predicant(args[0]);
+  uint found_types;
+  m_comparator.set_handler(type_handler_varchar.type_handler_for_comparison());
+  max_length= 1;
+
+  if (prepare_predicant_and_values(thd, &found_types))
+  {
+    DBUG_ASSERT(thd->is_error()); // Must set error
+    return TRUE;
+  }
+
+  if (!arg_types_compatible && comparator_count() == 2)
+  {
+    /*
+      Catch a special case: a mixture of signed and unsigned integer types.
+      in_longlong can handle such cases.
+
+      Note, prepare_predicant_and_values() aggregates this mixture as follows:
+      - signed+unsigned produce &type_handler_newdecimal.
+      - signed+signed or unsigned+unsigned produce &type_handler_slonglong
+      So we have extactly two distinct handlers.
+
+      The code below assumes that unsigned longlong is handled
+      by &type_handler_slonglong in comparison context,
+      which may change in the future to &type_handler_ulonglong.
+      The DBUG_ASSERT is needed to address this change here properly.
+    */
+    DBUG_ASSERT(type_handler_ulonglong.type_handler_for_comparison() ==
+                &type_handler_slonglong);
+    // Let's check if all arguments are of integer types
+    uint found_int_args= 0;
+    for (uint i= 0; i < arg_count; i++, found_int_args++)
+    {
+      if (args[i]->type_handler_for_comparison() != &type_handler_slonglong)
+        break;
+    }
+    if (found_int_args == arg_count)
+    {
+      // All arguments are integers. Switch to integer comparison.
+      arg_types_compatible= true;
+      DBUG_EXECUTE_IF("Item_func_in",
+                      push_warning_printf(thd, Sql_condition::WARN_LEVEL_NOTE,
+                      ER_UNKNOWN_ERROR, "DBUG: found a mix of UINT and SINT"););
+      m_comparator.set_handler(&type_handler_slonglong);
+    }
+  }
+
+  if (arg_types_compatible) // Bisection condition #1
+  {
+    if (m_comparator.type_handler()->
+        Item_func_in_fix_comparator_compatible_types(thd, this))
+      return TRUE;
+  }
+  else
+  {
+    DBUG_ASSERT(m_comparator.cmp_type() != ROW_RESULT);
+    if (fix_for_scalar_comparison_using_cmp_items(thd, found_types))
+      return TRUE;
+  }
+
+  DBUG_EXECUTE_IF("Item_func_in",
+                  push_warning_printf(thd, Sql_condition::WARN_LEVEL_NOTE,
+                  ER_UNKNOWN_ERROR, "DBUG: types_compatible=%s bisect=%s",
+                  arg_types_compatible ? "yes" : "no",
+                  array != NULL ? "yes" : "no"););
+  raise_note_if_key_become_unused(thd, old_predicant);
+  return FALSE;
+}
+
+
+/**
+  Populate Item_func_in::array with constant not-NULL arguments and sort them.
+
+  Sets "have_null" to true if some of the values appeared to be NULL.
+  Note, explicit NULLs were found during prepare_predicant_and_values().
+  So "have_null" can already be true before the fix_in_vector() call.
+  Here we additionally catch implicit NULLs.
+*/
+void Item_func_in::fix_in_vector()
+{
+  DBUG_ASSERT(array);
+  uint j=0;
+  for (uint i=1 ; i < arg_count ; i++)
+  {
+    if (!array->set(j,args[i]))
+      j++; // include this cell in the array.
+    else
+    {
+      /*
+        We don't put NULL values in array, to avoid erronous matches in
+        bisection.
+      */
+      have_null= 1;
+    }
+  }
+  if ((array->used_count= j))
+    array->sort();
+}
+
+
+/**
+  Convert all items in <in value list> to INT.
+
+  IN must compare INT columns and constants as int values (the same
+  way as equality does).
+  So we must check here if the column on the left and all the constant
+  values on the right can be compared as integers and adjust the
+  comparison type accordingly.
+
+  See the comment about the similar block in Item_bool_func2
+*/
+bool Item_func_in::value_list_convert_const_to_int(THD *thd)
+{
+  if (args[0]->real_item()->type() == FIELD_ITEM &&
+      !thd->lex->is_view_context_analysis())
+  {
+    Item_field *field_item= (Item_field*) (args[0]->real_item());
+    if (field_item->field_type() == MYSQL_TYPE_LONGLONG ||
+        field_item->field_type() == MYSQL_TYPE_YEAR)
+    {
+      bool all_converted= true;
+      Item **arg, **arg_end;
+      for (arg=args+1, arg_end=args+arg_count; arg != arg_end ; arg++)
+      {
+          /*
+            Explicit NULLs should not affect data cmp_type resolution:
+            - we ignore NULLs when calling collect_cmp_type()
+            - we ignore NULLs here
+            So this expression:
+              year_column IN (DATE'2001-01-01', NULL)
+            switches from TIME_RESULT to INT_RESULT.
+          */
+          if (arg[0]->type() != Item::NULL_ITEM &&
+              !convert_const_to_int(thd, field_item, &arg[0]))
+           all_converted= false;
+      }
+      if (all_converted)
+        m_comparator.set_handler(&type_handler_slonglong);
+    }
+  }
+  return thd->is_fatal_error; // Catch errrors in convert_const_to_int
+}
+
+
+bool cmp_item_row::
+      aggregate_row_elements_for_comparison(THD *thd,
+                                            Type_handler_hybrid_field_type *cmp,
+                                            Item_args *tmp,
+                                            const LEX_CSTRING &funcname,
+                                            uint col,
+                                            uint level)
+{
+  DBUG_EXECUTE_IF("cmp_item",
+  {
+    for (uint i= 0 ; i < tmp->argument_count(); i++)
+    {
+      Item *arg= tmp->arguments()[i];
+      push_warning_printf(thd, Sql_condition::WARN_LEVEL_NOTE,
+                          ER_UNKNOWN_ERROR, "DBUG: %*s[%d,%d] handler=%s",
+                          level, "", col, i,
+                          arg->type_handler()->name().ptr());
+    }
+  }
+  );
+  bool err= cmp->aggregate_for_comparison(funcname, tmp->arguments(),
+                                          tmp->argument_count(), true);
+  DBUG_EXECUTE_IF("cmp_item",
+  {
+    if (!err)
+      push_warning_printf(thd, Sql_condition::WARN_LEVEL_NOTE,
+                          ER_UNKNOWN_ERROR, "DBUG: %*s=> handler=%s",
+                          level,"",
+                          cmp->type_handler()->name().ptr());
+  }
+  );
+  return err;
+}
+
+
+bool cmp_item_row::prepare_comparators(THD *thd, const LEX_CSTRING &funcname,
+                                       const Item_args *args, uint level)
+{
+  DBUG_EXECUTE_IF("cmp_item",
+                  push_warning_printf(thd, Sql_condition::WARN_LEVEL_NOTE,
+                  ER_UNKNOWN_ERROR, "DBUG: %*sROW(%d args) level=%d",
+                                      level,"",
+                  args->argument_count(), level););
+  DBUG_ASSERT(args->argument_count() > 0);
+  if (alloc_comparators(thd, args->arguments()[0]->cols()))
+    return true;
+  DBUG_ASSERT(n == args->arguments()[0]->cols());
+  for (uint col= 0; col < n; col++)
+  {
+    Item_args tmp;
+    Type_handler_hybrid_field_type cmp;
+
+    if (tmp.alloc_and_extract_row_elements(thd, args, col) ||
+        aggregate_row_elements_for_comparison(thd, &cmp, &tmp,
+                                              funcname, col, level + 1))
+      return true;
+
+    /*
+      There is a legacy bug (MDEV-11511) in the code below,
+      which should be fixed eventually.
+      When performing:
+       (predicant0,predicant1) IN ((value00,value01),(value10,value11))
+      It uses only the data type and the collation of the predicant
+      elements only. It should be fixed to take into account the data type and
+      the collation for all elements at the N-th positions of the
+      predicate and all values:
+      - predicate0, value00, value01
+      - predicate1, value10, value11
+    */
+    Item *item0= args->arguments()[0]->element_index(col);
+    CHARSET_INFO *collation= item0->collation.collation;
+    if (!(comparators[col]= cmp.type_handler()->make_cmp_item(thd, collation)))
+      return true;
+    if (cmp.type_handler() == &type_handler_row)
+    {
+      // Prepare comparators for ROW elements recursively
+      cmp_item_row *row= static_cast<cmp_item_row*>(comparators[col]);
+      if (row->prepare_comparators(thd, funcname, &tmp, level + 1))
+        return true;
+    }
+  }
+  return false;
+}
+
+
+bool Item_func_in::fix_for_row_comparison_using_bisection(THD *thd)
+{
+  if (unlikely(!(array= new (thd->mem_root) in_row(thd, arg_count-1, 0))))
+    return true;
+  cmp_item_row *cmp= &((in_row*)array)->tmp;
+  if (cmp->prepare_comparators(thd, func_name_cstring(), this, 0))
+    return true;
+  fix_in_vector();
+  return false;
+}
+
+
+/**
+  This method is called for scalar data types when bisection is not possible,
+    for example:
+  - Some of args[1..arg_count] are not constants.
+  - args[1..arg_count] are constants, but pairs {args[0],args[1..arg_count]}
+    are compared by different data types, e.g.:
+      WHERE decimal_expr IN (1, 1e0)
+    The pair {args[0],args[1]} is compared by type_handler_decimal.
+    The pair {args[0],args[2]} is compared by type_handler_double.
+*/
+bool Item_func_in::fix_for_scalar_comparison_using_cmp_items(THD *thd,
+                                                             uint found_types)
+{
+  if (found_types & (1U << STRING_RESULT) &&
+      agg_arg_charsets_for_comparison(cmp_collation, args, arg_count))
+    return true;
+  if (make_unique_cmp_items(thd, cmp_collation.collation))
+    return true;
+  return false;
+}
+
+
+/**
+  This method is called for the ROW data type when bisection is not possible.
+*/
+bool Item_func_in::fix_for_row_comparison_using_cmp_items(THD *thd)
+{
+  if (make_unique_cmp_items(thd, cmp_collation.collation))
+    return true;
+  DBUG_ASSERT(get_comparator_type_handler(0) == &type_handler_row);
+  DBUG_ASSERT(get_comparator_cmp_item(0));
+  cmp_item_row *cmp_row= (cmp_item_row*) get_comparator_cmp_item(0);
+  return cmp_row->prepare_comparators(thd, func_name_cstring(), this, 0);
+}
+
+
+void Item_func_in::print(String *str, enum_query_type query_type)
+{
+  args[0]->print_parenthesised(str, query_type, precedence());
+  if (negated)
+    str->append(STRING_WITH_LEN(" not"));
+  str->append(STRING_WITH_LEN(" in ("));
+  print_args(str, 1, query_type);
+  str->append(STRING_WITH_LEN(")"));
+}
+
+
+/*
+  Evaluate the function and return its value.
+
+  SYNOPSIS
+    val_int()
+
+  DESCRIPTION
+    Evaluate the function and return its value.
+
+  IMPLEMENTATION
+    If the array object is defined then the value of the function is
+    calculated by means of this array.
+    Otherwise several cmp_item objects are used in order to do correct
+    comparison of left expression and an expression from the values list.
+    One cmp_item object correspond to one used comparison type. Left
+    expression can be evaluated up to number of different used comparison
+    types. A bit mapped variable value_added_map is used to check whether
+    the left expression already was evaluated for a particular result type.
+    Result types are mapped to it according to their integer values i.e.
+    STRING_RESULT is mapped to bit 0, REAL_RESULT to bit 1, so on.
+
+  RETURN
+    Value of the function
+*/
+
+longlong Item_func_in::val_int()
+{
+  DBUG_ASSERT(fixed());
+  if (array)
+  {
+    bool tmp=array->find(args[0]);
+    /*
+      NULL on left -> UNKNOWN.
+      Found no match, and NULL on right -> UNKNOWN.
+      NULL on right can never give a match, as it is not stored in
+      array.
+      See also the 'bisection_possible' variable in fix_length_and_dec().
+    */
+    null_value=args[0]->null_value || (!tmp && have_null);
+    return (longlong) (!null_value && tmp != negated);
+  }
+
+  if ((null_value= args[0]->real_item()->type() == NULL_ITEM))
+    return 0;
+
+  null_value= have_null;
+  uint idx;
+  if (!Predicant_to_list_comparator::cmp(this, &idx, &null_value))
+  {
+    null_value= false;
+    return (longlong) (!negated);
+  }
+  return (longlong) (!null_value && negated);
+}
+
+
+void Item_func_in::mark_as_condition_AND_part(TABLE_LIST *embedding)
+{
+  THD *thd= current_thd;
+
+  Query_arena *arena, backup;
+  arena= thd->activate_stmt_arena_if_needed(&backup);
+
+  if (!transform_into_subq_checked)
+  {
+    if ((transform_into_subq= to_be_transformed_into_in_subq(thd)))
+      thd->lex->current_select->in_funcs.push_back(this, thd->mem_root);
+    transform_into_subq_checked= true;
+  }
+
+  if (arena)
+    thd->restore_active_arena(arena, &backup);
+
+  emb_on_expr_nest= embedding;
+}
+
+
+class Func_handler_bit_or_int_to_ulonglong:
+        public Item_handled_func::Handler_ulonglong
+{
+public:
+  Longlong_null to_longlong_null(Item_handled_func *item) const
+  {
+    DBUG_ASSERT(item->fixed());
+    Longlong_null a= item->arguments()[0]->to_longlong_null();
+    return a.is_null() ? a : a | item->arguments()[1]->to_longlong_null();
+  }
+};
+
+
+class Func_handler_bit_or_dec_to_ulonglong:
+        public Item_handled_func::Handler_ulonglong
+{
+public:
+  Longlong_null to_longlong_null(Item_handled_func *item) const
+  {
+    DBUG_ASSERT(item->fixed());
+    VDec a(item->arguments()[0]);
+    return a.is_null() ? Longlong_null() :
+      a.to_xlonglong_null() | VDec(item->arguments()[1]).to_xlonglong_null();
+  }
+};
+
+
+bool Item_func_bit_or::fix_length_and_dec(THD *thd)
+{
+  static Func_handler_bit_or_int_to_ulonglong ha_int_to_ull;
+  static Func_handler_bit_or_dec_to_ulonglong ha_dec_to_ull;
+  return fix_length_and_dec_op2_std(&ha_int_to_ull, &ha_dec_to_ull);
+}
+
+
+class Func_handler_bit_and_int_to_ulonglong:
+        public Item_handled_func::Handler_ulonglong
+{
+public:
+  Longlong_null to_longlong_null(Item_handled_func *item) const
+  {
+    DBUG_ASSERT(item->fixed());
+    Longlong_null a= item->arguments()[0]->to_longlong_null();
+    return a.is_null() ? a : a & item->arguments()[1]->to_longlong_null();
+  }
+};
+
+
+class Func_handler_bit_and_dec_to_ulonglong:
+        public Item_handled_func::Handler_ulonglong
+{
+public:
+  Longlong_null to_longlong_null(Item_handled_func *item) const
+  {
+    DBUG_ASSERT(item->fixed());
+    VDec a(item->arguments()[0]);
+    return a.is_null() ?  Longlong_null() :
+      a.to_xlonglong_null() & VDec(item->arguments()[1]).to_xlonglong_null();
+  }
+};
+
+
+bool Item_func_bit_and::fix_length_and_dec(THD *thd)
+{
+  static Func_handler_bit_and_int_to_ulonglong ha_int_to_ull;
+  static Func_handler_bit_and_dec_to_ulonglong ha_dec_to_ull;
+  return fix_length_and_dec_op2_std(&ha_int_to_ull, &ha_dec_to_ull);
+}
+
+Item_cond::Item_cond(THD *thd, Item_cond *item)
+  :Item_bool_func(thd, item),
+   and_tables_cache(item->and_tables_cache)
+{
+  base_flags|= (item->base_flags & item_base_t::AT_TOP_LEVEL);
+
+  /*
+    item->list will be copied by copy_andor_arguments() call
+  */
+}
+
+
+Item_cond::Item_cond(THD *thd, Item *i1, Item *i2):
+  Item_bool_func(thd)
+{
+  list.push_back(i1, thd->mem_root);
+  list.push_back(i2, thd->mem_root);
+}
+
+
+Item *Item_cond_and::copy_andor_structure(THD *thd)
+{
+  Item_cond_and *item;
+  if ((item= new (thd->mem_root) Item_cond_and(thd, this)))
+    item->copy_andor_arguments(thd, this);
+  return item;
+}
+
+
+void Item_cond::copy_andor_arguments(THD *thd, Item_cond *item)
+{
+  List_iterator_fast<Item> li(item->list);
+  while (Item *it= li++)
+    list.push_back(it->copy_andor_structure(thd), thd->mem_root);
+}
+
+
+bool
+Item_cond::fix_fields(THD *thd, Item **ref)
+{
+  DBUG_ASSERT(fixed() == 0);
+  List_iterator<Item> li(list);
+  Item *item;
+  uchar buff[sizeof(char*)];			// Max local vars in function
+
+  not_null_tables_cache= 0;
+  used_tables_and_const_cache_init();
+
+  /*
+    and_table_cache is the value that Item_cond_or() returns for
+    not_null_tables()
+  */
+  and_tables_cache= ~(table_map) 0;
+
+  if (check_stack_overrun(thd, STACK_MIN_SIZE, buff))
+    return TRUE;				// Fatal error flag is set!
+
+  while (li++)
+  {
+    merge_sub_condition(li);
+    item= *li.ref();
+    if (is_top_level_item())
+      item->top_level_item();
+
+    /*
+      replace degraded condition:
+        was:    <field>
+        become: <field> != 0
+    */
+    Item::Type type= item->type();
+    if (type == Item::FIELD_ITEM || type == Item::REF_ITEM)
+    {
+      Query_arena backup, *arena;
+      Item *new_item;
+      arena= thd->activate_stmt_arena_if_needed(&backup);
+      if ((new_item= new (thd->mem_root) Item_func_ne(thd, item, new (thd->mem_root) Item_int(thd, 0, 1))))
+        li.replace(item= new_item);
+      if (arena)
+        thd->restore_active_arena(arena, &backup);
+    }
+
+    if (item->fix_fields_if_needed_for_bool(thd, li.ref()))
+      return TRUE; /* purecov: inspected */
+    merge_sub_condition(li);
+    item= *li.ref(); // may be substituted in fix_fields/merge_item_if_possible
+
+    used_tables_and_const_cache_join(item);
+    base_flags|= item->base_flags & item_base_t::MAYBE_NULL;
+    with_flags|= item->with_flags;
+  }
+  (void) eval_not_null_tables((void*) 0);
+
+  /*
+    We have to set fixed as some other items will check it and fail if we
+    do not. This can be changed when we properly check if fix_fields()
+    fails in call cases.
+  */
+  base_flags|= item_base_t::FIXED;
+  if (fix_length_and_dec(thd) || thd->is_error())
+    return TRUE;
+  return FALSE;
+}
+
+
+/**
+  @brief
+  Merge a lower-level condition pointed by the iterator into this Item_cond
+  if possible
+
+  @param li         list iterator pointing to condition that must be
+                    examined and merged if possible.
+
+  @details
+  If an item pointed by the iterator is an instance of Item_cond with the
+  same functype() as this Item_cond (i.e. both are Item_cond_and or both are
+  Item_cond_or) then the arguments of that lower-level item can be merged
+  into the list of arguments of this upper-level Item_cond.
+
+  This optimization reduces the depth of an AND-OR tree.
+  E.g. a WHERE clause like
+    F1 AND (F2 AND (F2 AND F4))
+  is parsed into a tree with the same nested structure as defined
+  by braces. This optimization will transform such tree into
+    AND (F1, F2, F3, F4).
+  Trees of OR items are flattened as well:
+    ((F1 OR F2) OR (F3 OR F4))   =>   OR (F1, F2, F3, F4)
+  Items for removed AND/OR levels will dangle until the death of the
+  entire statement.
+
+  The optimization is currently prepared statements and stored procedures
+  friendly as it doesn't allocate any memory and its effects are durable
+  (i.e. do not depend on PS/SP arguments).
+*/
+void Item_cond::merge_sub_condition(List_iterator<Item>& li)
+{
+  Item *item= *li.ref();
+
+  /*
+    The check for list.is_empty() is to catch empty Item_cond_and() items.
+    We may encounter Item_cond_and with an empty list, because optimizer code
+    strips multiple equalities, combines items, then adds multiple equalities
+    back
+  */
+  while (item->type() == Item::COND_ITEM &&
+         ((Item_cond*) item)->functype() == functype() &&
+         !((Item_cond*) item)->list.is_empty())
+  {
+    li.replace(((Item_cond*) item)->list);
+    ((Item_cond*) item)->list.empty();
+    item= *li.ref();
+  }
+}
+
+/*
+  Calculate not_null_tables_cache and and_tables_cache.
+*/
+
+bool
+Item_cond::eval_not_null_tables(void *opt_arg)
+{
+  Item *item;
+  bool is_and_cond= functype() == Item_func::COND_AND_FUNC;
+  List_iterator<Item> li(list);
+  bool found= 0;
+
+  not_null_tables_cache= (table_map) 0;
+  and_tables_cache= ~(table_map) 0;
+  while ((item=li++))
+  {
+    if (item->can_eval_in_optimize() &&
+        !item->with_sp_var() && !item->with_param() &&
+        !cond_has_datetime_is_null(item) && is_top_level_item())
+    {
+      if (item->eval_const_cond() == is_and_cond)
+      {
+        /* 
+          a. This is "... AND true_cond AND ..."
+          In this case, true_cond  has no effect on cond_and->not_null_tables()
+          b. This is "... OR false_cond/null cond OR ..." 
+          In this case, false_cond has no effect on cond_or->not_null_tables()
+        */
+      }
+      else
+      {
+        /* 
+          a. This is "... AND false_cond/null_cond AND ..."
+          The whole condition is FALSE/UNKNOWN.
+          b. This is  "... OR const_cond OR ..."
+          In this case, cond_or->not_null_tables()=0, because the condition
+          const_cond might evaluate to true (regardless of whether some tables
+          were NULL-complemented).
+        */
+        found= 1;
+        not_null_tables_cache= (table_map) 0;
+        and_tables_cache= (table_map) 0;
+      }
+    }
+    else
+    {
+      table_map tmp_table_map= item->not_null_tables();
+      if (!found)
+      {
+        /* We should not depend on the order of items */
+        not_null_tables_cache|= tmp_table_map;
+      }
+      and_tables_cache&= tmp_table_map;
+    }
+  }
+  return 0;
+}
+
+
+/**
+   @note
+     This implementation of the virtual function find_not_null_fields()
+     infers null-rejectedness if fields from tables marked in 'allowed' from
+     this condition.
+     Currently only top level AND conjuncts that  are not disjunctions are used
+     for the inference. Usage of any top level and-or formula with l OR levels
+     would require a stack of bitmaps for fields of the height h=2*l+1 So we
+     would have to allocate h-1 additional field bitmaps for each table marked
+     in 'allowed'.
+*/
+
+bool
+Item_cond::find_not_null_fields(table_map allowed)
+{
+  Item *item;
+  bool is_and_cond= functype() == Item_func::COND_AND_FUNC;
+  if (!is_and_cond)
+  {
+    /* Now only fields of top AND level conjuncts are taken into account */
+    return false;
+  }
+  uint isnull_func_cnt= 0;
+  List_iterator<Item> li(list);
+  while ((item=li++))
+  {
+    bool is_mult_eq= item->type() == Item::FUNC_ITEM &&
+         ((Item_func *) item)->functype() == Item_func::MULT_EQUAL_FUNC;
+    if (is_mult_eq)
+    {
+      if (!item->find_not_null_fields(allowed))
+        continue;
+    }
+
+    if (~allowed & item->used_tables())
+      continue;
+
+    /* It is assumed that all constant conjuncts are already eliminated */
+
+    /*
+      First infer null-rejectedness of fields from all conjuncts but
+      IS NULL predicates
+    */
+    bool isnull_func= item->type() == Item::FUNC_ITEM &&
+         ((Item_func *) item)->functype() == Item_func::ISNULL_FUNC;
+    if (isnull_func)
+    {
+      isnull_func_cnt++;
+      continue;
+    }
+    if (!item->find_not_null_fields(allowed))
+      continue;
+  }
+
+  /* Now try no get contradictions using IS NULL conjuncts */
+  if (isnull_func_cnt)
+  {
+    li.rewind();
+    while ((item=li++) && isnull_func_cnt)
+    {
+      if (~allowed & item->used_tables())
+        continue;
+
+      bool isnull_func= item->type() == Item::FUNC_ITEM &&
+           ((Item_func *) item)->functype() == Item_func::ISNULL_FUNC;
+      if (isnull_func)
+      {
+        if  (item->find_not_null_fields(allowed))
+          return true;
+        isnull_func_cnt--;
+      }
+    }
+  }
+  return false;
+}
+
+void Item_cond::fix_after_pullout(st_select_lex *new_parent, Item **ref,
+                                  bool merge)
+{
+  List_iterator<Item> li(list);
+  Item *item;
+
+  used_tables_and_const_cache_init();
+
+  and_tables_cache= ~(table_map) 0; // Here and below we do as fix_fields does
+  not_null_tables_cache= 0;
+
+  while ((item=li++))
+  {
+    table_map tmp_table_map;
+    item->fix_after_pullout(new_parent, li.ref(), merge);
+    item= *li.ref();
+    used_tables_and_const_cache_join(item);
+
+    if (item->const_item())
+      and_tables_cache= (table_map) 0;
+    else
+    {
+      tmp_table_map= item->not_null_tables();
+      not_null_tables_cache|= tmp_table_map;
+      and_tables_cache&= tmp_table_map;
+      const_item_cache= FALSE;
+    }  
+  }
+}
+
+
+bool Item_cond::walk(Item_processor processor, bool walk_subquery, void *arg)
+{
+  List_iterator_fast<Item> li(list);
+  Item *item;
+  while ((item= li++))
+    if (item->walk(processor, walk_subquery, arg))
+      return 1;
+  return Item_func::walk(processor, walk_subquery, arg);
+}
+
+/**
+  Transform an Item_cond object with a transformer callback function.
+  
+    The function recursively applies the transform method to each
+     member item of the condition list.
+    If the call of the method for a member item returns a new item
+    the old item is substituted for a new one.
+    After this the transformer is applied to the root node
+    of the Item_cond object. 
+     
+  @param transformer   the transformer callback function to be applied to
+                       the nodes of the tree of the object
+  @param arg           parameter to be passed to the transformer
+
+  @return
+    Item returned as the result of transformation of the root node 
+*/
+
+Item *Item_cond::do_transform(THD *thd, Item_transformer transformer, uchar *arg,
+                              bool toplevel)
+{
+  DBUG_ASSERT(!thd->stmt_arena->is_stmt_prepare());
+
+  List_iterator<Item> li(list);
+  Item *item;
+  while ((item= li++))
+  {
+    Item *new_item= toplevel ? item->top_level_transform(thd, transformer, arg)
+                             : item->transform(thd, transformer, arg);
+    if (!new_item)
+      return 0;
+
+    /*
+      THD::change_item_tree() should be called only if the tree was
+      really transformed, i.e. when a new item has been created.
+      Otherwise we'll be allocating a lot of unnecessary memory for
+      change records at each execution.
+    */
+    if (toplevel)
+      *li.ref()= new_item;
+    else if (new_item != item)
+      thd->change_item_tree(li.ref(), new_item);
+  }
+  return Item_func::transform(thd, transformer, arg);
+}
+
+
+/**
+  Compile Item_cond object with a processor and a transformer
+  callback functions.
+  
+    First the function applies the analyzer to the root node of
+    the Item_func object. Then if the analyzer succeeeds (returns TRUE)
+    the function recursively applies the compile method to member
+    item of the condition list.
+    If the call of the method for a member item returns a new item
+    the old item is substituted for a new one.
+    After this the transformer is applied to the root node
+    of the Item_cond object. 
+     
+  @param analyzer      the analyzer callback function to be applied to the
+                       nodes of the tree of the object
+  @param[in,out] arg_p parameter to be passed to the analyzer
+  @param transformer   the transformer callback function to be applied to the
+                       nodes of the tree of the object
+  @param arg_t         parameter to be passed to the transformer
+
+  @return
+    Item returned as the result of transformation of the root node 
+*/
+
+Item *Item_cond::do_compile(THD *thd, Item_analyzer analyzer, uchar **arg_p,
+                      Item_transformer transformer, uchar *arg_t, bool toplevel)
+{
+  if (!(this->*analyzer)(arg_p))
+    return 0;
+  
+  List_iterator<Item> li(list);
+  Item *item;
+  while ((item= li++))
+  {
+    /* 
+      The same parameter value of arg_p must be passed
+      to analyze any argument of the condition formula.
+    */   
+    uchar *arg_v= *arg_p;
+    Item *new_item= item->compile(thd, analyzer, &arg_v, transformer, arg_t);
+    if (!new_item || new_item == item)
+      continue;
+    if (toplevel)
+      *li.ref()= new_item;
+    else
+      thd->change_item_tree(li.ref(), new_item);
+  }
+  return Item_func::transform(thd, transformer, arg_t);
+}
+
+
+Item *Item_cond::propagate_equal_fields(THD *thd,
+                                        const Context &ctx,
+                                        COND_EQUAL *cond)
+{
+  DBUG_ASSERT(!thd->stmt_arena->is_stmt_prepare());
+  DBUG_ASSERT(arg_count == 0);
+  List_iterator<Item> li(list);
+  while (li++)
+  {
+    /*
+      The exact value of the last parameter to propagate_and_change_item_tree()
+      is not important at this point. Item_func derivants will create and
+      pass their own context to the arguments.
+    */
+    propagate_and_change_item_tree(thd, li.ref(), cond, Context_boolean());
+  }
+  return this;
+}
+
+void Item_cond::traverse_cond(Cond_traverser traverser,
+                              void *arg, traverse_order order)
+{
+  List_iterator<Item> li(list);
+  Item *item;
+
+  switch(order) {
+  case(PREFIX):
+    (*traverser)(this, arg);
+    while ((item= li++))
+    {
+      item->traverse_cond(traverser, arg, order);
+    }
+    (*traverser)(NULL, arg);
+    break;
+  case(POSTFIX):
+    while ((item= li++))
+    {
+      item->traverse_cond(traverser, arg, order);
+    }
+    (*traverser)(this, arg);
+  }
+}
+
+/**
+  Move SUM items out from item tree and replace with reference.
+
+  The split is done to get an unique item for each SUM function
+  so that we can easily find and calculate them.
+  (Calculation done by update_sum_func() and copy_sum_funcs() in
+  sql_select.cc)
+
+  @param thd			Thread handler
+  @param ref_pointer_array	Pointer to array of reference fields
+  @param fields		All fields in select
+
+  @note
+    This function is run on all expression (SELECT list, WHERE, HAVING etc)
+    that have or refer (HAVING) to a SUM expression.
+*/
+
+void Item_cond::split_sum_func(THD *thd, Ref_ptr_array ref_pointer_array,
+                               List<Item> &fields, uint flags)
+{
+  List_iterator<Item> li(list);
+  Item *item;
+  while ((item= li++))
+    item->split_sum_func2(thd, ref_pointer_array, fields, li.ref(),
+                          flags | SPLIT_SUM_SKIP_REGISTERED);
+}
+
+
+table_map
+Item_cond::used_tables() const
+{						// This caches used_tables
+  return used_tables_cache;
+}
+
+
+void Item_cond::print(String *str, enum_query_type query_type)
+{
+  List_iterator_fast<Item> li(list);
+  Item *item;
+  if ((item=li++))
+    item->print_parenthesised(str, query_type, precedence());
+  while ((item=li++))
+  {
+    str->append(' ');
+    str->append(func_name_cstring());
+    str->append(' ');
+    item->print_parenthesised(str, query_type, precedence());
+  }
+}
+
+
+void Item_cond::neg_arguments(THD *thd)
+{
+  List_iterator<Item> li(list);
+  Item *item;
+  while ((item= li++))		/* Apply not transformation to the arguments */
+  {
+    Item *new_item= item->neg_transformer(thd);
+    if (!new_item)
+    {
+      if (!(new_item= new (thd->mem_root) Item_func_not(thd, item)))
+	return;					// Fatal OEM error
+    }
+    (void) li.replace(new_item);
+  }
+}
+
+
+/**
+  @brief
+    Building clone for Item_cond
+    
+  @param thd        thread handle
+  @param mem_root   part of the memory for the clone   
+
+  @details
+    This method gets copy of the current item and also 
+    build clones for its elements. For this elements 
+    build_copy is called again.
+      
+   @retval
+     clone of the item
+     0 if an error occurred
+*/ 
+
+Item *Item_cond::build_clone(THD *thd)
+{
+  List_iterator_fast<Item> li(list);
+  Item *item;
+  Item_cond *copy= (Item_cond *) get_copy(thd);
+  if (!copy)
+    return 0;
+  copy->list.empty();
+  while ((item= li++))
+  {
+    Item *arg_clone= item->build_clone(thd);
+    if (!arg_clone)
+      return 0;
+    if (copy->list.push_back(arg_clone, thd->mem_root))
+      return 0;
+  }
+  return copy;
+}
+
+
+bool Item_cond::excl_dep_on_table(table_map tab_map)
+{
+  if (used_tables() & (OUTER_REF_TABLE_BIT | RAND_TABLE_BIT))
+    return false;
+  if (!(used_tables() & ~tab_map))
+    return true;
+  List_iterator_fast<Item> li(list);
+  Item *item;
+  while ((item= li++))
+  {
+    if (!item->excl_dep_on_table(tab_map))
+      return false;
+  }
+  return true;
+}
+
+
+bool Item_cond::excl_dep_on_grouping_fields(st_select_lex *sel)
+{
+  if (has_rand_bit())
+    return false;
+  List_iterator_fast<Item> li(list);
+  Item *item;
+  while ((item= li++))
+  {
+    if (!item->excl_dep_on_grouping_fields(sel))
+      return false;
+  }
+  return true;
+}
+
+
+void Item_cond_and::mark_as_condition_AND_part(TABLE_LIST *embedding)
+{
+  List_iterator<Item> li(list);
+  Item *item;
+  while ((item=li++))
+  {
+    item->mark_as_condition_AND_part(embedding);
+  }
+}
+
+/**
+  Evaluation of AND(expr, expr, expr ...).
+
+  @note
+    There are AND expressions for which we don't care if the
+    result is NULL or 0. This is the case for:
+    - WHERE clause
+    - HAVING clause
+    - IF(expression)
+    For these we mark them as "top_level_items"
+
+  @retval
+    1  If all expressions are true
+  @retval
+    0  If any of the expressions are false or if we find a NULL expression and
+       this is a top_level_item.
+  @retval
+    NULL if all expression are either 1 or NULL
+*/
+
+
+longlong Item_cond_and::val_int()
+{
+  DBUG_ASSERT(fixed());
+  List_iterator_fast<Item> li(list);
+  Item *item;
+  null_value= 0;
+  while ((item=li++))
+  {
+    if (!item->val_bool())
+    {
+      if (is_top_level_item() || !(null_value= item->null_value))
+        return 0;
+    }
+  }
+  return null_value ? 0 : 1;
+}
+
+
+longlong Item_cond_or::val_int()
+{
+  DBUG_ASSERT(fixed());
+  List_iterator_fast<Item> li(list);
+  Item *item;
+  null_value=0;
+  while ((item=li++))
+  {
+    if (item->val_bool())
+    {
+      null_value=0;
+      return 1;
+    }
+    if (item->null_value)
+      null_value=1;
+  }
+  return 0;
+}
+
+Item *Item_cond_or::copy_andor_structure(THD *thd)
+{
+  Item_cond_or *item;
+  if ((item= new (thd->mem_root) Item_cond_or(thd, this)))
+    item->copy_andor_arguments(thd, this);
+  return item;
+}
+
+
+/**
+  Create an AND expression from two expressions.
+
+  @param a	expression or NULL
+  @param b    	expression.
+  @param org_item	Don't modify a if a == *org_item.
+                        If a == NULL, org_item is set to point at b,
+                        to ensure that future calls will not modify b.
+
+  @note
+    This will not modify item pointed to by org_item or b
+    The idea is that one can call this in a loop and create and
+    'and' over all items without modifying any of the original items.
+
+  @retval
+    NULL	Error
+  @retval
+    Item
+*/
+
+Item *and_expressions(THD *thd, Item *a, Item *b, Item **org_item)
+{
+  if (!a)
+    return (*org_item= (Item*) b);
+  if (a == *org_item)
+  {
+    Item_cond *res;
+    if ((res= new (thd->mem_root) Item_cond_and(thd, a, (Item*) b)))
+    {
+      res->used_tables_cache= a->used_tables() | b->used_tables();
+      res->not_null_tables_cache= a->not_null_tables() | b->not_null_tables();
+    }
+    return res;
+  }
+  if (((Item_cond_and*) a)->add((Item*) b, thd->mem_root))
+    return 0;
+  ((Item_cond_and*) a)->used_tables_cache|= b->used_tables();
+  ((Item_cond_and*) a)->not_null_tables_cache|= b->not_null_tables();
+  return a;
+}
+
+
+bool Item_func_null_predicate::count_sargable_conds(void *arg)
+{
+  ((SELECT_LEX*) arg)->cond_count++;
+  return 0;
+}
+
+
+longlong Item_func_isnull::val_int()
+{
+  DBUG_ASSERT(fixed());
+  if (const_item() && !args[0]->maybe_null())
+    return 0;
+  return args[0]->is_null() ? 1: 0;
+}
+
+
+bool Item_func_isnull::find_not_null_fields(table_map allowed)
+{
+  if (!(~allowed & used_tables()) &&
+      args[0]->real_item()->type() == Item::FIELD_ITEM)
+  {
+    Field *field= ((Item_field *)(args[0]->real_item()))->field;
+    if (bitmap_is_set(&field->table->tmp_set, field->field_index))
+      return true;
+  }
+  return false;
+}
+
+
+void Item_func_isnull::print(String *str, enum_query_type query_type)
+{
+  if (const_item() && !args[0]->maybe_null() &&
+      !(query_type & (QT_NO_DATA_EXPANSION | QT_VIEW_INTERNAL)))
+    str->append(STRING_WITH_LEN("/*always not null*/ 1"));
+  else
+    args[0]->print_parenthesised(str, query_type, precedence());
+  str->append(STRING_WITH_LEN(" is null"));
+}
+
+
+longlong Item_is_not_null_test::val_int()
+{
+  DBUG_ASSERT(fixed());
+  DBUG_ENTER("Item_is_not_null_test::val_int");
+  if (const_item() && !args[0]->maybe_null())
+    DBUG_RETURN(1);
+  if (args[0]->is_null())
+  {
+    DBUG_PRINT("info", ("null"));
+    owner->was_null|= 1;
+    DBUG_RETURN(0);
+  }
+  else
+    DBUG_RETURN(1);
+}
+
+/**
+  Optimize case of not_null_column IS NULL.
+*/
+void Item_is_not_null_test::update_used_tables()
+{
+  if (!args[0]->maybe_null())
+    used_tables_cache= 0;			/* is always true */
+  else
+    args[0]->update_used_tables();
+}
+
+
+longlong Item_func_isnotnull::val_int()
+{
+  DBUG_ASSERT(fixed());
+  return args[0]->is_null() ? 0 : 1;
+}
+
+
+void Item_func_isnotnull::print(String *str, enum_query_type query_type)
+{
+  args[0]->print_parenthesised(str, query_type, precedence());
+  str->append(STRING_WITH_LEN(" is not null"));
+}
+
+
+bool Item_bool_func2::count_sargable_conds(void *arg)
+{
+  ((SELECT_LEX*) arg)->cond_count++;
+  return 0;
+}
+
+void Item_func_like::print(String *str, enum_query_type query_type)
+{
+  args[0]->print_parenthesised(str, query_type, precedence());
+  str->append(' ');
+  if (negated)
+    str->append(STRING_WITH_LEN(" not "));
+  str->append(func_name_cstring());
+  str->append(' ');
+  if (escape_used_in_parsing)
+  {
+    args[1]->print_parenthesised(str, query_type, precedence());
+    str->append(STRING_WITH_LEN(" escape "));
+    escape_item->print_parenthesised(str, query_type, higher_precedence());
+  }
+  else
+    args[1]->print_parenthesised(str, query_type, higher_precedence());
+}
+
+
+longlong Item_func_like::val_int()
+{
+  DBUG_ASSERT(fixed());
+  DBUG_ASSERT(escape != ESCAPE_NOT_INITIALIZED);
+  String* res= args[0]->val_str(&cmp_value1);
+  if (args[0]->null_value)
+  {
+    null_value=1;
+    return 0;
+  }
+  String* res2= args[1]->val_str(&cmp_value2);
+  if (args[1]->null_value)
+  {
+    null_value=1;
+    return 0;
+  }
+  null_value=0;
+  if (canDoTurboBM)
+    return turboBM_matches(res->ptr(), res->length()) ? !negated : negated;
+  return cmp_collation.collation->wildcmp(
+		    res->ptr(),res->ptr()+res->length(),
+		    res2->ptr(),res2->ptr()+res2->length(),
+		    escape,wild_one,wild_many) ? negated : !negated;
+}
+
+
+/**
+  We can optimize a where if first character isn't a wildcard
+*/
+
+bool Item_func_like::with_sargable_pattern() const
+{
+  if (negated)
+    return false;
+
+  if (!args[1]->can_eval_in_optimize())
+    return false;
+
+  String* res2= args[1]->val_str((String *) &cmp_value2);
+  if (!res2)
+    return false;
+
+  if (!res2->length()) // Can optimize empty wildcard: column LIKE ''
+    return true;
+
+  DBUG_ASSERT(res2->ptr());
+  char first= res2->ptr()[0];
+  return first != wild_many && first != wild_one;
+}
+
+
+/*
+  subject LIKE pattern
+  removes subject's dependency on PAD_CHAR_TO_FULL_LENGTH
+  if pattern ends with the '%' wildcard.
+*/
+Sql_mode_dependency Item_func_like::value_depends_on_sql_mode() const
+{
+  if (!args[1]->value_depends_on_sql_mode_const_item())
+    return Item_func::value_depends_on_sql_mode();
+  StringBuffer<64> patternbuf;
+  String *pattern= args[1]->val_str_ascii(&patternbuf);
+  if (!pattern || !pattern->length())
+    return Sql_mode_dependency();                  // Will return NULL or 0
+  DBUG_ASSERT(pattern->charset()->mbminlen == 1);
+  if (pattern->ptr()[pattern->length() - 1] != '%')
+    return Item_func::value_depends_on_sql_mode();
+  return ((args[0]->value_depends_on_sql_mode() |
+           args[1]->value_depends_on_sql_mode()) &
+          Sql_mode_dependency(~0, ~MODE_PAD_CHAR_TO_FULL_LENGTH)).
+         soft_to_hard();
+}
+
+
+SEL_TREE *Item_func_like::get_mm_tree(RANGE_OPT_PARAM *param, Item **cond_ptr)
+{
+  MEM_ROOT *tmp_root= param->mem_root;
+  param->thd->mem_root= param->old_root;
+  bool sargable_pattern= with_sargable_pattern();
+  param->thd->mem_root= tmp_root;
+  return sargable_pattern ?
+    Item_bool_func2::get_mm_tree(param, cond_ptr) :
+    Item_func::get_mm_tree(param, cond_ptr);
+}
+
+
+bool fix_escape_item(THD *thd, Item *escape_item, String *tmp_str,
+                     bool escape_used_in_parsing, CHARSET_INFO *cmp_cs,
+                     int *escape)
+{
+  /*
+    ESCAPE clause accepts only constant arguments and Item_param.
+
+    Subqueries during context_analysis_only might decide they're
+    const_during_execution, but not quite const yet, not evaluate-able.
+    This is fine, as most of context_analysis_only modes will never
+    reach val_int(), so we won't need the value.
+    CONTEXT_ANALYSIS_ONLY_DERIVED being a notable exception here.
+  */
+  if (!escape_item->const_during_execution() ||
+     (!escape_item->const_item() &&
+      !(thd->lex->context_analysis_only & ~CONTEXT_ANALYSIS_ONLY_DERIVED)))
+  {
+    my_error(ER_WRONG_ARGUMENTS,MYF(0),"ESCAPE");
+    return TRUE;
+  }
+
+  IF_DBUG(*escape= ESCAPE_NOT_INITIALIZED,);
+
+  if (escape_item->const_item())
+  {
+    /* If we are on execution stage */
+    /* XXX is it safe to evaluate is_expensive() items here? */
+    String *escape_str= escape_item->val_str(tmp_str);
+    if (escape_str)
+    {
+      const char *escape_str_ptr= escape_str->ptr();
+      if (escape_used_in_parsing && (
+             (((thd->variables.sql_mode & MODE_NO_BACKSLASH_ESCAPES) &&
+                escape_str->numchars() != 1) ||
+               escape_str->numchars() > 1)))
+      {
+        my_error(ER_WRONG_ARGUMENTS,MYF(0),"ESCAPE");
+        return TRUE;
+      }
+
+      if (cmp_cs->use_mb())
+      {
+        CHARSET_INFO *cs= escape_str->charset();
+        my_wc_t wc;
+        int rc= cs->mb_wc(&wc,
+                          (const uchar*) escape_str_ptr,
+                          (const uchar*) escape_str_ptr +
+                          escape_str->length());
+        *escape= (int) (rc > 0 ? wc : '\\');
+      }
+      else
+      {
+        /*
+          In the case of 8bit character set, we pass native
+          code instead of Unicode code as "escape" argument.
+          Convert to "cs" if charset of escape differs.
+        */
+        uint32 unused;
+        if (escape_str->needs_conversion(escape_str->length(),
+                                         escape_str->charset(),cmp_cs,&unused))
+        {
+          char ch;
+          uint errors;
+          uint32 cnvlen= copy_and_convert(&ch, 1, cmp_cs, escape_str_ptr,
+                                          escape_str->length(),
+                                          escape_str->charset(), &errors);
+          *escape= cnvlen ? ch : '\\';
+        }
+        else
+          *escape= escape_str_ptr ? *escape_str_ptr : '\\';
+      }
+    }
+    else
+      *escape= '\\';
+  }
+
+  return FALSE;
+}
+
+bool Item_func_like::fix_fields(THD *thd, Item **ref)
+{
+  DBUG_ASSERT(fixed() == 0);
+  if (Item_bool_func2::fix_fields(thd, ref) ||
+      escape_item->fix_fields_if_needed_for_scalar(thd, &escape_item) ||
+      fix_escape_item(thd, escape_item, &cmp_value1, escape_used_in_parsing,
+                      cmp_collation.collation, &escape))
+    return TRUE;
+
+  if (escape_item->const_item())
+  {
+    /*
+      We could also do boyer-more for non-const items, but as we would have to
+      recompute the tables for each row it's not worth it.
+    */
+    if (args[1]->can_eval_in_optimize() && !use_strnxfrm(collation.collation))
+    {
+      String* res2= args[1]->val_str(&cmp_value2);
+      if (!res2)
+        return FALSE;				// Null argument
+      
+      const size_t len= res2->length();
+
+      /*
+        len must be > 2 ('%pattern%')
+        heuristic: only do TurboBM for pattern_len > 2
+      */
+      if (len <= 2)
+        return FALSE;
+
+      const char*  first= res2->ptr();
+      const char*  last=  first + len - 1;
+      
+      if (len > MIN_TURBOBM_PATTERN_LEN + 2 &&
+          *first == wild_many &&
+          *last  == wild_many)
+      {
+        const char* tmp = first + 1;
+        for (; *tmp != wild_many && *tmp != wild_one && *tmp != escape; tmp++) ;
+        canDoTurboBM = (tmp == last) && !args[0]->collation.collation->use_mb();
+      }
+      if (canDoTurboBM)
+      {
+        pattern_len = (int) len - 2;
+        pattern     = thd->strmake(first + 1, pattern_len);
+        DBUG_PRINT("info", ("Initializing pattern: '%s'", first));
+        int *suff = (int*) thd->alloc((int) (sizeof(int)*
+                                      ((pattern_len + 1)*2+
+                                      alphabet_size)));
+        bmGs      = suff + pattern_len + 1;
+        bmBc      = bmGs + pattern_len + 1;
+        turboBM_compute_good_suffix_shifts(suff);
+        turboBM_compute_bad_character_shifts();
+        DBUG_PRINT("info",("done"));
+      }
+      use_sampling= (len > 2 && (*first == wild_many || *first == wild_one));
+    }
+  }
+  return FALSE;
+}
+
+
+void Item_func_like::cleanup()
+{
+  canDoTurboBM= FALSE;
+  Item_bool_func2::cleanup();
+}
+
+
+bool Item_func_like::find_selective_predicates_list_processor(void *arg)
+{
+  find_selective_predicates_list_processor_data *data=
+    (find_selective_predicates_list_processor_data *) arg;
+  if (use_sampling && used_tables() == data->table->map)
+  {
+    THD *thd= data->table->in_use;
+    COND_STATISTIC *stat;
+    Item *arg0;
+    if (!(stat= (COND_STATISTIC *) thd->alloc(sizeof(COND_STATISTIC))))
+      return TRUE;
+    stat->cond= this;
+    arg0= args[0]->real_item();
+    if (args[1]->const_item() && arg0->type() == FIELD_ITEM)
+      stat->field_arg= ((Item_field *)arg0)->field;
+    else
+      stat->field_arg= NULL;
+    data->list.push_back(stat, thd->mem_root);
+  }
+  return FALSE;
+}
+
+
+int Regexp_processor_pcre::default_regex_flags()
+{
+  return default_regex_flags_pcre(current_thd);
+}
+
+void Regexp_processor_pcre::cleanup()
+{
+  pcre2_match_data_free(m_pcre_match_data);
+  pcre2_code_free(m_pcre);
+  reset();
+}
+
+void Regexp_processor_pcre::init(CHARSET_INFO *data_charset, int extra_flags)
+{
+  m_library_flags= default_regex_flags() | extra_flags |
+                  (data_charset != &my_charset_bin ?
+                   (PCRE2_UTF | PCRE2_UCP) : 0) |
+                  ((data_charset->state &
+                    (MY_CS_BINSORT | MY_CS_CSSORT)) ? 0 : PCRE2_CASELESS);
+
+  // Convert text data to utf-8.
+  m_library_charset= data_charset == &my_charset_bin ?
+                     &my_charset_bin : &my_charset_utf8mb3_general_ci;
+
+  m_conversion_is_needed= (data_charset != &my_charset_bin) &&
+                          !my_charset_same(data_charset, m_library_charset);
+}
+
+/**
+  Convert string to lib_charset, if needed.
+*/
+String *Regexp_processor_pcre::convert_if_needed(String *str, String *converter)
+{
+  if (m_conversion_is_needed)
+  {
+    uint dummy_errors;
+    if (converter->copy(str->ptr(), str->length(), str->charset(),
+                        m_library_charset, &dummy_errors))
+      return NULL;
+    str= converter;
+  }
+  return str;
+}
+
+
+/**
+  @brief Compile regular expression.
+
+  @param[in]    pattern        the pattern to compile from.
+  @param[in]    send_error     send error message if any.
+
+  @details Make necessary character set conversion then 
+  compile regular expression passed in the args[1].
+
+  @retval    false  success.
+  @retval    true   error occurred.
+ */
+
+bool Regexp_processor_pcre::compile(String *pattern, bool send_error)
+{
+  int pcreErrorNumber;
+  PCRE2_SIZE pcreErrorOffset;
+
+  if (is_compiled())
+  {
+    if (!stringcmp(pattern, &m_prev_pattern))
+      return false;
+    cleanup();
+    m_prev_pattern.copy(*pattern);
+  }
+
+  if (!(pattern= convert_if_needed(pattern, &pattern_converter)))
+    return true;
+
+  pcre2_compile_context *cctx= NULL;
+#ifndef pcre2_set_depth_limit
+  // old pcre2 uses stack - put a limit on that (new pcre2 prefers heap)
+  cctx= pcre2_compile_context_create(NULL);
+  pcre2_set_compile_recursion_guard(cctx, [](uint32_t cur, void *end) -> int
+    { return available_stack_size(&cur, end) < STACK_MIN_SIZE; },
+    current_thd->mysys_var->stack_ends_here);
+#endif
+  m_pcre= pcre2_compile((PCRE2_SPTR8) pattern->ptr(), pattern->length(),
+                        m_library_flags,
+                        &pcreErrorNumber, &pcreErrorOffset, cctx);
+  pcre2_compile_context_free(cctx); // NULL is ok here
+
+  if (unlikely(m_pcre == NULL))
+  {
+    if (send_error)
+    {
+      char buff[MAX_FIELD_WIDTH];
+      int lmsg= pcre2_get_error_message(pcreErrorNumber,
+                                        (PCRE2_UCHAR8 *)buff, sizeof(buff));
+      if (lmsg >= 0)
+        my_snprintf(buff+lmsg, sizeof(buff)-lmsg,
+                    " at offset %d", pcreErrorOffset);
+      my_error(ER_REGEXP_ERROR, MYF(0), buff);
+    }
+    return true;
+  }
+  m_pcre_match_data= pcre2_match_data_create_from_pattern(m_pcre, NULL);
+  if (m_pcre_match_data == NULL)
+  {
+    my_error(ER_OUT_OF_RESOURCES, MYF(0));
+    return true;
+  }
+  return false;
+}
+
+
+bool Regexp_processor_pcre::compile(Item *item, bool send_error)
+{
+  char buff[MAX_FIELD_WIDTH];
+  String tmp(buff, sizeof(buff), &my_charset_bin);
+  String *pattern= item->val_str(&tmp);
+  if (unlikely(item->null_value) || (unlikely(compile(pattern, send_error))))
+    return true;
+  return false;
+}
+
+
+/**
+  Send a warning explaining an error code returned by pcre_exec().
+*/
+void Regexp_processor_pcre::pcre_exec_warn(int rc) const
+{
+  PCRE2_UCHAR8 buf[128];
+  THD *thd= current_thd;
+
+  int errlen= pcre2_get_error_message(rc, buf, sizeof(buf));
+  if (errlen <= 0)
+  {
+    my_snprintf((char *)buf, sizeof(buf), "pcre_exec: Internal error (%d)", rc);
+  }
+  push_warning_printf(thd, Sql_condition::WARN_LEVEL_WARN,
+                      ER_REGEXP_ERROR, ER_THD(thd, ER_REGEXP_ERROR), buf);
+}
+
+
+/**
+  Call pcre_exec() and send a warning if pcre_exec() returned with an error.
+*/
+int Regexp_processor_pcre::pcre_exec_with_warn(const pcre2_code *code,
+                                               pcre2_match_data *data,
+                                               const char *subject,
+                                               int length, int startoffset,
+                                               int options)
+{
+  pcre2_match_context *mctx= NULL;
+#ifndef pcre2_set_depth_limit
+  // old pcre2 uses stack - put a limit on that (new pcre2 prefers heap)
+  mctx= pcre2_match_context_create(NULL);
+  pcre2_set_recursion_limit(mctx,
+    available_stack_size(&mctx, current_thd->mysys_var->stack_ends_here)/544);
+#endif
+  int rc= pcre2_match(code, (PCRE2_SPTR8) subject, (PCRE2_SIZE) length,
+                      (PCRE2_SIZE) startoffset, options, data, mctx);
+  pcre2_match_context_free(mctx); // NULL is ok here
+  DBUG_EXECUTE_IF("pcre_exec_error_123", rc= -123;);
+  if (unlikely(rc < PCRE2_ERROR_NOMATCH))
+  {
+    m_SubStrVec= NULL;
+    pcre_exec_warn(rc);
+  }
+  else
+    m_SubStrVec= pcre2_get_ovector_pointer(data);
+  return rc;
+}
+
+
+bool Regexp_processor_pcre::exec(const char *str, size_t length, size_t offset)
+{
+  m_pcre_exec_rc= pcre_exec_with_warn(m_pcre, m_pcre_match_data,
+                                      str, (int)length, (int)offset, 0);
+  return false;
+}
+
+
+bool Regexp_processor_pcre::exec(String *str, int offset,
+                                  uint n_result_offsets_to_convert)
+{
+  if (!(str= convert_if_needed(str, &subject_converter)))
+    return true;
+  m_pcre_exec_rc= pcre_exec_with_warn(m_pcre, m_pcre_match_data,
+                                      str->ptr(), str->length(), offset, 0);
+  if (m_pcre_exec_rc > 0)
+  {
+    uint i;
+    for (i= 0; i < n_result_offsets_to_convert; i++)
+    {
+      /*
+        Convert byte offset into character offset.
+      */
+      m_SubStrVec[i]= (int) str->charset()->numchars(str->ptr(),
+                                                     str->ptr() +
+                                                     m_SubStrVec[i]);
+    }
+  }
+  return false;
+}
+
+
+bool Regexp_processor_pcre::exec(Item *item, int offset,
+                                uint n_result_offsets_to_convert)
+{
+  char buff[MAX_FIELD_WIDTH];
+  String tmp(buff,sizeof(buff),&my_charset_bin);
+  String *res= item->val_str(&tmp);
+  if (item->null_value)
+    return true;
+  return exec(res, offset, n_result_offsets_to_convert);
+}
+
+
+void Regexp_processor_pcre::fix_owner(Item_func *owner,
+                                      Item *subject_arg,
+                                      Item *pattern_arg)
+{
+  if (!is_compiled() &&
+      pattern_arg->const_item() &&
+      !pattern_arg->is_expensive())
+  {
+    if (compile(pattern_arg, true))
+    {
+      owner->set_maybe_null(); // Will always return NULL
+      return;
+    }
+    set_const(true);
+    owner->base_flags|= subject_arg->base_flags & item_base_t::MAYBE_NULL;
+  }
+  else
+    owner->set_maybe_null();
+}
+
+
+bool
+Item_func_regex::fix_length_and_dec(THD *thd)
+{
+  if (Item_bool_func::fix_length_and_dec(thd) ||
+      agg_arg_charsets_for_comparison(cmp_collation, args, 2))
+    return TRUE;
+
+  re.init(cmp_collation.collation, 0);
+  re.fix_owner(this, args[0], args[1]);
+  return FALSE;
+}
+
+
+longlong Item_func_regex::val_int()
+{
+  DBUG_ASSERT(fixed());
+  if ((null_value= re.recompile(args[1])))
+    return 0;
+
+  if ((null_value= re.exec(args[0], 0, 0)))
+    return 0;
+
+  return re.match();
+}
+
+
+bool
+Item_func_regexp_instr::fix_length_and_dec(THD *thd)
+{
+  if (agg_arg_charsets_for_comparison(cmp_collation, args, 2))
+    return TRUE;
+
+  re.init(cmp_collation.collation, 0);
+  re.fix_owner(this, args[0], args[1]);
+  max_length= MY_INT32_NUM_DECIMAL_DIGITS; // See also Item_func_locate
+  return FALSE;
+}
+
+
+longlong Item_func_regexp_instr::val_int()
+{
+  DBUG_ASSERT(fixed());
+  if ((null_value= re.recompile(args[1])))
+    return 0;
+
+  if ((null_value= re.exec(args[0], 0, 1)))
+    return 0;
+
+  return re.match() ? (longlong) (re.subpattern_start(0) + 1) : 0;
+}
+
+
+#ifdef LIKE_CMP_TOUPPER
+#define likeconv(cs,A) (uchar) (cs)->toupper(A)
+#else
+#define likeconv(cs,A) (uchar) (cs)->sort_order[(uchar) (A)]
+#endif
+
+
+/**
+  Precomputation dependent only on pattern_len.
+*/
+
+void Item_func_like::turboBM_compute_suffixes(int *suff)
+{
+  const int   plm1 = pattern_len - 1;
+  int            f = 0;
+  int            g = plm1;
+  int *const splm1 = suff + plm1;
+  CHARSET_INFO	*cs= cmp_collation.collation;
+
+  *splm1 = pattern_len;
+
+  if (!cs->sort_order)
+  {
+    int i;
+    for (i = pattern_len - 2; i >= 0; i--)
+    {
+      int tmp = *(splm1 + i - f);
+      if (g < i && tmp < i - g)
+	suff[i] = tmp;
+      else
+      {
+	if (i < g)
+	  g = i; // g = MY_MIN(i, g)
+	f = i;
+	while (g >= 0 && pattern[g] == pattern[g + plm1 - f])
+	  g--;
+	suff[i] = f - g;
+      }
+    }
+  }
+  else
+  {
+    int i;
+    for (i = pattern_len - 2; 0 <= i; --i)
+    {
+      int tmp = *(splm1 + i - f);
+      if (g < i && tmp < i - g)
+	suff[i] = tmp;
+      else
+      {
+	if (i < g)
+	  g = i; // g = MY_MIN(i, g)
+	f = i;
+	while (g >= 0 &&
+	       likeconv(cs, pattern[g]) == likeconv(cs, pattern[g + plm1 - f]))
+	  g--;
+	suff[i] = f - g;
+      }
+    }
+  }
+}
+
+
+/**
+  Precomputation dependent only on pattern_len.
+*/
+
+void Item_func_like::turboBM_compute_good_suffix_shifts(int *suff)
+{
+  turboBM_compute_suffixes(suff);
+
+  int *end = bmGs + pattern_len;
+  int *k;
+  for (k = bmGs; k < end; k++)
+    *k = pattern_len;
+
+  int tmp;
+  int i;
+  int j          = 0;
+  const int plm1 = pattern_len - 1;
+  for (i = plm1; i > -1; i--)
+  {
+    if (suff[i] == i + 1)
+    {
+      for (tmp = plm1 - i; j < tmp; j++)
+      {
+	int *tmp2 = bmGs + j;
+	if (*tmp2 == pattern_len)
+	  *tmp2 = tmp;
+      }
+    }
+  }
+
+  int *tmp2;
+  for (tmp = plm1 - i; j < tmp; j++)
+  {
+    tmp2 = bmGs + j;
+    if (*tmp2 == pattern_len)
+      *tmp2 = tmp;
+  }
+
+  tmp2 = bmGs + plm1;
+  for (i = 0; i <= pattern_len - 2; i++)
+    *(tmp2 - suff[i]) = plm1 - i;
+}
+
+
+/**
+   Precomputation dependent on pattern_len.
+*/
+
+void Item_func_like::turboBM_compute_bad_character_shifts()
+{
+  int *i;
+  int *end = bmBc + alphabet_size;
+  int j;
+  const int plm1 = pattern_len - 1;
+  CHARSET_INFO	*cs= cmp_collation.collation;
+
+  for (i = bmBc; i < end; i++)
+    *i = pattern_len;
+
+  if (!cs->sort_order)
+  {
+    for (j = 0; j < plm1; j++)
+      bmBc[(uint) (uchar) pattern[j]] = plm1 - j;
+  }
+  else
+  {
+    for (j = 0; j < plm1; j++)
+      bmBc[(uint) likeconv(cs,pattern[j])] = plm1 - j;
+  }
+}
+
+
+/**
+  Search for pattern in text.
+
+  @return
+    returns true/false for match/no match
+*/
+
+bool Item_func_like::turboBM_matches(const char* text, int text_len) const
+{
+  int bcShift;
+  int turboShift;
+  int shift = pattern_len;
+  int j     = 0;
+  int u     = 0;
+  CHARSET_INFO	*cs= cmp_collation.collation;
+
+  const int plm1=  pattern_len - 1;
+  const int tlmpl= text_len - pattern_len;
+
+  /* Searching */
+  if (!cs->sort_order)
+  {
+    while (j <= tlmpl)
+    {
+      int i= plm1;
+      while (i >= 0 && pattern[i] == text[i + j])
+      {
+	i--;
+	if (i == plm1 - shift)
+	  i-= u;
+      }
+      if (i < 0)
+	return 1;
+
+      const int v= plm1 - i;
+      turboShift = u - v;
+      bcShift    = bmBc[(uint) (uchar) text[i + j]] - plm1 + i;
+      shift      = MY_MAX(turboShift, bcShift);
+      shift      = MY_MAX(shift, bmGs[i]);
+      if (shift == bmGs[i])
+	u = MY_MIN(pattern_len - shift, v);
+      else
+      {
+	if (turboShift < bcShift)
+	  shift = MY_MAX(shift, u + 1);
+	u = 0;
+      }
+      j+= shift;
+    }
+    return 0;
+  }
+  else
+  {
+    while (j <= tlmpl)
+    {
+      int i= plm1;
+      while (i >= 0 && likeconv(cs,pattern[i]) == likeconv(cs,text[i + j]))
+      {
+	i--;
+	if (i == plm1 - shift)
+	  i-= u;
+      }
+      if (i < 0)
+	return 1;
+
+      const int v= plm1 - i;
+      turboShift = u - v;
+      bcShift    = bmBc[(uint) likeconv(cs, text[i + j])] - plm1 + i;
+      shift      = MY_MAX(turboShift, bcShift);
+      shift      = MY_MAX(shift, bmGs[i]);
+      if (shift == bmGs[i])
+	u = MY_MIN(pattern_len - shift, v);
+      else
+      {
+	if (turboShift < bcShift)
+	  shift = MY_MAX(shift, u + 1);
+	u = 0;
+      }
+      j+= shift;
+    }
+    return 0;
+  }
+}
+
+
+/**
+  Make a logical XOR of the arguments.
+
+  If either operator is NULL, return NULL.
+
+  @todo
+    (low priority) Change this to be optimized as: @n
+    A XOR B   ->  (A) == 1 AND (B) <> 1) OR (A <> 1 AND (B) == 1) @n
+    To be able to do this, we would however first have to extend the MySQL
+    range optimizer to handle OR better.
+
+  @note
+    As we don't do any index optimization on XOR this is not going to be
+    very fast to use.
+*/
+
+longlong Item_func_xor::val_int()
+{
+  DBUG_ASSERT(fixed());
+  int result= 0;
+  null_value= false;
+  for (uint i= 0; i < arg_count; i++)
+  {
+    result^= (args[i]->val_int() != 0);
+    if (args[i]->null_value)
+    {
+      null_value= true;
+      return 0;
+    }
+  }
+  return result;
+}
+
+/**
+  Apply NOT transformation to the item and return a new one.
+
+
+    Transform the item using next rules:
+    @verbatim
+       a AND b AND ...    -> NOT(a) OR NOT(b) OR ...
+       a OR b OR ...      -> NOT(a) AND NOT(b) AND ...
+       NOT(a)             -> a
+       a = b              -> a != b
+       a != b             -> a = b
+       a < b              -> a >= b
+       a >= b             -> a < b
+       a > b              -> a <= b
+       a <= b             -> a > b
+       IS NULL(a)         -> IS NOT NULL(a)
+       IS NOT NULL(a)     -> IS NULL(a)
+    @endverbatim
+
+  @param thd		thread handler
+
+  @return
+    New item or
+    NULL if we cannot apply NOT transformation (see Item::neg_transformer()).
+*/
+
+Item *Item_func_not::neg_transformer(THD *thd)	/* NOT(x)  ->  x */
+{
+  return args[0];
+}
+
+
+bool Item_func_not::fix_fields(THD *thd, Item **ref)
+{
+  args[0]->under_not(this);
+  if (args[0]->type() == FIELD_ITEM)
+  {
+    /* replace  "NOT <field>" with "<field> == 0" */
+    Query_arena backup, *arena;
+    Item *new_item;
+    bool rc= TRUE;
+    arena= thd->activate_stmt_arena_if_needed(&backup);
+    if ((new_item= new (thd->mem_root) Item_func_eq(thd, args[0], new (thd->mem_root) Item_int(thd, 0, 1))))
+    {
+      new_item->name= name;
+      rc= (*ref= new_item)->fix_fields(thd, ref);
+    }
+    if (arena)
+      thd->restore_active_arena(arena, &backup);
+    return rc;
+  }
+  return Item_func::fix_fields(thd, ref);
+}
+
+
+Item *Item_bool_rowready_func2::neg_transformer(THD *thd)
+{
+  Item *item= negated_item(thd);
+  return item;
+}
+
+/**
+  XOR can be negated by negating one of the operands:
+
+  NOT (a XOR b)  => (NOT a) XOR b
+                 => a       XOR (NOT b)
+
+  @param thd     Thread handle
+  @return        New negated item
+*/
+Item *Item_func_xor::neg_transformer(THD *thd)
+{
+  Item *neg_operand;
+  Item_func_xor *new_item;
+  if ((neg_operand= args[0]->neg_transformer(thd)))
+    // args[0] has neg_tranformer
+    new_item= new(thd->mem_root) Item_func_xor(thd, neg_operand, args[1]);
+  else if ((neg_operand= args[1]->neg_transformer(thd)))
+    // args[1] has neg_tranformer
+    new_item= new(thd->mem_root) Item_func_xor(thd, args[0], neg_operand);
+  else
+  {
+    neg_operand= new(thd->mem_root) Item_func_not(thd, args[0]);
+    new_item= new(thd->mem_root) Item_func_xor(thd, neg_operand, args[1]);
+  }
+  return new_item;
+}
+
+
+/**
+  a IS NULL  ->  a IS NOT NULL.
+*/
+Item *Item_func_isnull::neg_transformer(THD *thd)
+{
+  Item *item= new (thd->mem_root) Item_func_isnotnull(thd, args[0]);
+  return item;
+}
+
+
+/**
+  a IS NOT NULL  ->  a IS NULL.
+*/
+Item *Item_func_isnotnull::neg_transformer(THD *thd)
+{
+  Item *item= new (thd->mem_root) Item_func_isnull(thd, args[0]);
+  return item;
+}
+
+
+Item *Item_cond_and::neg_transformer(THD *thd)	/* NOT(a AND b AND ...)  -> */
+					/* NOT a OR NOT b OR ... */
+{
+  neg_arguments(thd);
+  Item *item= new (thd->mem_root) Item_cond_or(thd, list);
+  return item;
+}
+
+
+bool
+Item_cond_and::set_format_by_check_constraint(
+                                      Send_field_extended_metadata *to) const
+{
+  List_iterator_fast<Item> li(const_cast<List<Item>&>(list));
+  Item *item;
+  while ((item= li++))
+  {
+    if (item->set_format_by_check_constraint(to))
+      return true;
+  }
+  return false;
+}
+
+
+Item *Item_cond_or::neg_transformer(THD *thd)	/* NOT(a OR b OR ...)  -> */
+					/* NOT a AND NOT b AND ... */
+{
+  neg_arguments(thd);
+  Item *item= new (thd->mem_root) Item_cond_and(thd, list);
+  return item;
+}
+
+
+Item *Item_func_nop_all::neg_transformer(THD *thd)
+{
+  /* "NOT (e $cmp$ ANY (SELECT ...)) -> e $rev_cmp$" ALL (SELECT ...) */
+  Item_func_not_all *new_item= new (thd->mem_root) Item_func_not_all(thd, args[0]);
+  Item_allany_subselect *allany= (Item_allany_subselect*)args[0];
+  allany->create_comp_func(FALSE);
+  allany->all= !allany->all;
+  allany->upper_item= new_item;
+  return new_item;
+}
+
+Item *Item_func_not_all::neg_transformer(THD *thd)
+{
+  /* "NOT (e $cmp$ ALL (SELECT ...)) -> e $rev_cmp$" ANY (SELECT ...) */
+  Item_func_nop_all *new_item= new (thd->mem_root) Item_func_nop_all(thd, args[0]);
+  Item_allany_subselect *allany= (Item_allany_subselect*)args[0];
+  allany->all= !allany->all;
+  allany->create_comp_func(TRUE);
+  allany->upper_item= new_item;
+  return new_item;
+}
+
+Item *Item_func_eq::negated_item(THD *thd) /* a = b  ->  a != b */
+{
+  return new (thd->mem_root) Item_func_ne(thd, args[0], args[1]);
+}
+
+
+Item *Item_func_ne::negated_item(THD *thd) /* a != b  ->  a = b */
+{
+  return new (thd->mem_root) Item_func_eq(thd, args[0], args[1]);
+}
+
+
+Item *Item_func_lt::negated_item(THD *thd) /* a < b  ->  a >= b */
+{
+  return new (thd->mem_root) Item_func_ge(thd, args[0], args[1]);
+}
+
+
+Item *Item_func_ge::negated_item(THD *thd) /* a >= b  ->  a < b */
+{
+  return new (thd->mem_root) Item_func_lt(thd, args[0], args[1]);
+}
+
+
+Item *Item_func_gt::negated_item(THD *thd) /* a > b  ->  a <= b */
+{
+  return new (thd->mem_root) Item_func_le(thd, args[0], args[1]);
+}
+
+
+Item *Item_func_le::negated_item(THD *thd) /* a <= b  ->  a > b */
+{
+  return new (thd->mem_root) Item_func_gt(thd, args[0], args[1]);
+}
+
+/**
+  just fake method, should never be called.
+*/
+Item *Item_bool_rowready_func2::negated_item(THD *thd)
+{
+  DBUG_ASSERT(0);
+  return 0;
+}
+
+
+/**
+  Construct a minimal multiple equality item
+
+  @param f1               the first equal item
+  @param f2               the second equal item
+  @param with_const_item  TRUE if the first item is constant
+
+  @details
+  The constructor builds a new item equal object for the equality f1=f2.
+  One of the equal items can be constant. If this is the case it is passed
+  always as the first parameter and the parameter with_const_item serves
+  as an indicator of this case.
+  Currently any non-constant parameter items must point to an item of the
+  of the type Item_field or Item_direct_view_ref(Item_field). 
+*/
+
+Item_equal::Item_equal(THD *thd, const Type_handler *handler,
+                       Item *f1, Item *f2, bool with_const_item):
+  Item_bool_func(thd), eval_item(0), cond_false(0), cond_true(0),
+  context_field(NULL), link_equal_fields(FALSE),
+  m_compare_handler(handler),
+  m_compare_collation(f2->collation.collation)
+{
+  const_item_cache= 0;
+  with_const= with_const_item;
+  equal_items.push_back(f1, thd->mem_root);
+  equal_items.push_back(f2, thd->mem_root);
+  upper_levels= NULL;
+}
+
+
+/**
+  Copy constructor for a multiple equality
+  
+  @param item_equal   source item for the constructor
+
+  @details
+  The function creates a copy of an Item_equal object.
+  This constructor is used when an item belongs to a multiple equality
+  of an upper level (an upper AND/OR level or an upper level of a nested
+  outer join).
+*/
+
+Item_equal::Item_equal(THD *thd, Item_equal *item_equal):
+  Item_bool_func(thd), eval_item(0), cond_false(0), cond_true(0),
+  context_field(NULL), link_equal_fields(FALSE),
+  m_compare_handler(item_equal->m_compare_handler),
+  m_compare_collation(item_equal->m_compare_collation)
+{
+  const_item_cache= 0;
+  List_iterator_fast<Item> li(item_equal->equal_items);
+  Item *item;
+  while ((item= li++))
+  {
+    equal_items.push_back(item, thd->mem_root);
+  }
+  with_const= item_equal->with_const;
+  cond_false= item_equal->cond_false;
+  upper_levels= item_equal->upper_levels;
+}
+
+
+/**
+  @brief
+  Add a constant item to the Item_equal object
+
+  @param[in]  c  the constant to add
+  @param[in]  f  item from the list equal_items the item c is equal to
+                 (this parameter is optional)
+
+  @details
+  The method adds the constant item c to the equal_items list. If the list
+  doesn't have any constant item yet the item c is just put in the front
+  the list. Otherwise the value of c is compared with the value of the
+  constant item from equal_items. If they are not equal cond_false is set
+  to TRUE. This serves as an indicator that this Item_equal is always FALSE.
+*/
+
+void Item_equal::add_const(THD *thd, Item *c)
+{
+  if (cond_false)
+    return;
+  if (!with_const)
+  {
+    with_const= TRUE;
+    equal_items.push_front(c, thd->mem_root);
+    return;
+  }
+
+  /*
+    Suppose we have an expression (with a string type field) like this:
+      WHERE field=const1 AND field=const2 ...
+
+    For all pairs field=constXXX we know that:
+
+    - Item_func_eq::fix_length_and_dec() performed collation and character
+    set aggregation and added character set converters when needed.
+    Note, the case like:
+      WHERE field=const1 COLLATE latin1_bin AND field=const2
+    is not handled here, because the field would be replaced to
+    Item_func_set_collation, which cannot get into Item_equal.
+    So all constXXX that are handled by Item_equal
+    already have compatible character sets with "field".
+
+    - Also, Field_str::test_if_equality_guarantees_uniqueness() guarantees
+    that the comparison collation of all equalities handled by Item_equal
+    match the the collation of the field.
+
+    Therefore, at Item_equal::add_const() time all constants constXXX
+    should be directly comparable to each other without an additional
+    character set conversion.
+    It's safe to do val_str() for "const_item" and "c" and compare
+    them according to the collation of the *field*.
+
+    So in a script like this:
+      CREATE TABLE t1 (a VARCHAR(10) COLLATE xxx);
+      INSERT INTO t1 VALUES ('a'),('A');
+      SELECT * FROM t1 WHERE a='a' AND a='A';
+    Item_equal::add_const() effectively rewrites the condition to:
+      SELECT * FROM t1 WHERE a='a' AND 'a' COLLATE xxx='A';
+    and then to:
+      SELECT * FROM t1 WHERE a='a'; // if the two constants were equal
+                                    // e.g. in case of latin1_swedish_ci
+    or to:
+      SELECT * FROM t1 WHERE FALSE; // if the two constants were not equal
+                                    // e.g. in case of latin1_bin
+
+    Note, both "const_item" and "c" can return NULL, e.g.:
+      SELECT * FROM t1 WHERE a=NULL    AND a='const';
+      SELECT * FROM t1 WHERE a='const' AND a=NULL;
+      SELECT * FROM t1 WHERE a='const' AND a=(SELECT MAX(a) FROM t2)
+  */
+
+  cond_false= !Item_equal::compare_type_handler()->Item_eq_value(thd, this, c,
+                                                                 get_const());
+  if (with_const && equal_items.elements == 1)
+    cond_true= TRUE;
+  if (cond_false || cond_true)
+    const_item_cache= 1;
+}
+
+
+/**
+  @brief
+  Check whether a field is referred to in the multiple equality
+
+  @param field   field whose occurrence is to be checked
+
+  @details
+  The function checks whether field is referred to by one of the
+  items from the equal_items list.
+
+  @retval
+    1       if multiple equality contains a reference to field
+  @retval
+    0       otherwise    
+*/
+
+bool Item_equal::contains(Field *field)
+{
+  Item_equal_fields_iterator it(*this);
+  while (it++)
+  {
+    if (field->eq(it.get_curr_field()))
+        return 1;
+  }
+  return 0;
+}
+
+
+/**
+  @brief
+  Join members of another Item_equal object
+  
+  @param item    multiple equality whose members are to be joined
+
+  @details
+  The function actually merges two multiple equalities. After this operation
+  the Item_equal object additionally contains the field items of another item of
+  the type Item_equal.
+  If the optional constant items are not equal the cond_false flag is set to TRUE.
+
+  @notes
+  The function is called for any equality f1=f2 such that f1 and f2 are items
+  of the type Item_field or Item_direct_view_ref(Item_field), and, f1->field is
+  referred to in the list this->equal_items, while the list item->equal_items
+  contains a reference to f2->field.  
+*/
+
+void Item_equal::merge(THD *thd, Item_equal *item)
+{
+  Item *c= item->get_const();
+  if (c)
+    item->equal_items.pop();
+  equal_items.append(&item->equal_items);
+  if (c)
+  {
+    /* 
+      The flag cond_false will be set to TRUE after this if 
+      the multiple equality already contains a constant and its 
+      value is not equal to the value of c.
+    */
+    add_const(thd, c);
+  }
+  cond_false|= item->cond_false;
+} 
+
+
+/**
+  @brief
+  Merge members of another Item_equal object into this one
+  
+  @param item         multiple equality whose members are to be merged
+  @param save_merged  keep the list of equalities in 'item' intact
+                      (e.g. for other merges)
+
+  @details
+  If the Item_equal 'item' happens to have some elements of the list
+  of equal items belonging to 'this' object then the function merges
+  the equal items from 'item' into this list.
+  If both lists contains constants and they are different then
+  the value of the cond_false flag is set to TRUE.
+
+  @retval
+    1    the lists of equal items in 'item' and 'this' contain common elements 
+  @retval
+    0    otherwise 
+
+  @notes
+  The method 'merge' just joins the list of equal items belonging to 'item'
+  to the list of equal items belonging to this object assuming that the lists
+  are disjoint. It would be more correct to call the method 'join'.
+  The method 'merge_into_with_check' really merges two lists of equal items if
+  they have common members.  
+*/
+  
+bool Item_equal::merge_with_check(THD *thd, Item_equal *item, bool save_merged)
+{
+  bool intersected= FALSE;
+  Item_equal_fields_iterator_slow fi(*item);
+  
+  while (fi++)
+  {
+    if (contains(fi.get_curr_field()))
+    {
+      intersected= TRUE;
+      if (!save_merged)
+        fi.remove();
+    }
+  }
+  if (intersected)
+  {
+    if (!save_merged)
+      merge(thd, item);
+    else
+    {
+      Item *c= item->get_const();
+      if (c)
+        add_const(thd, c);
+      if (!cond_false)
+      {
+        Item *item;
+        fi.rewind();
+        while ((item= fi++))
+	{
+          if (!contains(fi.get_curr_field()))
+            add(item, thd->mem_root);
+        }
+      }
+    }         
+  }
+  return intersected;
+}
+
+
+/**
+  @brief
+  Merge this object into a list of Item_equal objects 
+  
+  @param list                 the list of Item_equal objects to merge into
+  @param save_merged          keep the list of equalities in 'this' intact
+                              (e.g. for other merges)
+  @param only_intersected     do not merge if there are no common members
+                              in any of Item_equal objects from the list
+                              and this Item_equal
+
+  @details
+  If the list of equal items from 'this' object contains common members
+  with the lists of equal items belonging to Item_equal objects from 'list'
+  then all involved Item_equal objects e1,...,ek are merged into one 
+  Item equal that replaces e1,...,ek in the 'list'. Otherwise, in the case
+  when the value of the parameter only_if_intersected is false, this
+  Item_equal is joined to the 'list'.
+*/
+
+void Item_equal::merge_into_list(THD *thd, List<Item_equal> *list,
+                                 bool save_merged,
+                                 bool only_intersected)
+{
+  Item_equal *item;
+  List_iterator<Item_equal> it(*list);
+  Item_equal *merge_into= NULL;
+  while((item= it++))
+  {
+    if (!merge_into)
+    {
+      if (item->merge_with_check(thd, this, save_merged))
+        merge_into= item;
+    }
+    else
+    {
+      if (merge_into->merge_with_check(thd, item, false))
+        it.remove();
+    }
+  }
+  if (!only_intersected && !merge_into)
+    list->push_back(this, thd->mem_root);
+}
+
+
+/**
+  @brief
+  Order equal items of the  multiple equality according to a sorting criteria
+
+  @param compare      function to compare items from the equal_items list
+  @param arg          context extra parameter for the cmp function
+
+  @details
+  The function performs ordering of the items from the equal_items list
+  according to the criteria determined by the cmp callback parameter.
+  If cmp(item1,item2,arg)<0 than item1 must be placed after item2.
+
+  @notes
+  The function sorts equal items by the bubble sort algorithm.
+  The list of field items is looked through and whenever two neighboring
+  members follow in a wrong order they are swapped. This is performed
+  again and again until we get all members in a right order.
+*/
+
+void Item_equal::sort(Item_field_cmpfunc compare, void *arg)
+{
+  bubble_sort<Item>(&equal_items, compare, arg);
+}
+
+
+/**
+  @brief
+  Check appearance of new constant items in the multiple equality object
+
+  @details
+  The function checks appearance of new constant items among the members
+  of the equal_items list. Each new constant item is compared with
+  the constant item from the list if there is any. If there is none the first
+  new constant item is placed at the very beginning of the list and
+  with_const is set to TRUE. If it happens that the compared constant items
+  are unequal then the flag cond_false is set to TRUE.
+
+  @notes 
+  Currently this function is called only after substitution of constant tables.
+*/
+
+void Item_equal::update_const(THD *thd)
+{
+  List_iterator<Item> it(equal_items);
+  if (with_const)
+    it++;
+  Item *item;
+  while ((item= it++))
+  {
+    if (item->can_eval_in_optimize() &&
+        /*
+          Don't propagate constant status of outer-joined column.
+          Such a constant status here is a result of:
+            a) empty outer-joined table: in this case such a column has a
+               value of NULL; but at the same time other arguments of
+               Item_equal don't have to be NULLs and the value of the whole
+               multiple equivalence expression doesn't have to be NULL or FALSE
+               because of the outer join nature;
+          or
+            b) outer-joined table contains only 1 row: the result of
+               this column is equal to a row field value *or* NULL.
+          Both values are inacceptable as Item_equal constants.
+        */
+        !item->is_outer_field())
+    {
+      if (item == equal_items.head())
+        with_const= TRUE;
+      else
+      {
+        it.remove();
+        add_const(thd, item);
+      }
+    } 
+  }
+}
+
+
+/**
+  @brief
+  Fix fields in a completely built multiple equality
+
+  @param  thd     currently not used thread handle 
+  @param  ref     not used
+
+  @details
+  This function is called once the multiple equality has been built out of 
+  the WHERE/ON condition and no new members are expected to be added to the
+  equal_items list anymore.
+  As any implementation of the virtual fix_fields method the function
+  calculates the cached values of not_null_tables_cache, used_tables_cache,
+  const_item_cache and calls fix_length_and_dec().
+  Additionally the function sets a reference to the Item_equal object in
+  the non-constant items of the equal_items list unless such a reference has
+  been already set.
+
+  @notes 
+  Currently this function is called only in the function
+  build_equal_items_for_cond.
+  
+  @retval
+  FALSE   always
+*/
+
+bool Item_equal::fix_fields(THD *thd, Item **ref)
+{ 
+  DBUG_ASSERT(fixed() == 0);
+  Item_equal_fields_iterator it(*this);
+  Item *item;
+  Field *first_equal_field= NULL;
+  Field *last_equal_field= NULL;
+  Field *prev_equal_field= NULL;
+  not_null_tables_cache= used_tables_cache= 0;
+  const_item_cache= 0;
+  while ((item= it++))
+  {
+    table_map tmp_table_map;
+    used_tables_cache|= item->used_tables();
+    tmp_table_map= item->not_null_tables();
+    not_null_tables_cache|= tmp_table_map;
+    DBUG_ASSERT(!item->with_sum_func() && !item->with_subquery());
+    if (item->maybe_null())
+      set_maybe_null();
+    if (!item->get_item_equal())
+      item->set_item_equal(this);
+    if (link_equal_fields && item->real_item()->type() == FIELD_ITEM)
+    {
+      last_equal_field= ((Item_field *) (item->real_item()))->field;
+      if (!prev_equal_field)
+        first_equal_field= last_equal_field;
+      else
+        prev_equal_field->next_equal_field= last_equal_field;
+      prev_equal_field= last_equal_field;         
+    }
+  }
+  if (prev_equal_field && last_equal_field != first_equal_field)
+    last_equal_field->next_equal_field= first_equal_field;
+  if (fix_length_and_dec(thd))
+    return TRUE;
+  base_flags|= item_base_t::FIXED;
+  return FALSE;
+}
+
+
+/**
+  Update the value of the used table attribute and other attributes
+ */
+
+void Item_equal::update_used_tables()
+{
+  not_null_tables_cache= used_tables_cache= 0;
+  if ((const_item_cache= cond_false || cond_true))
+    return;
+  Item_equal_fields_iterator it(*this);
+  Item *item;
+  const_item_cache= 1;
+  while ((item= it++))
+  {
+    item->update_used_tables();
+    used_tables_cache|= item->used_tables();
+    /* see commentary at Item_equal::update_const() */
+    const_item_cache&= item->const_item() && !item->is_outer_field();
+  }
+}
+
+
+/**
+  @note
+    This multiple equality can contains elements belonging not to tables {T}
+    marked in 'allowed' . So we can ascertain null-rejectedness of field f
+    belonging to table t from {T} only if one of the following equality
+    predicate can be  extracted from this multiple equality:
+    - f=const
+    - f=f' where f' is a field of some table from {T}
+*/
+
+bool Item_equal::find_not_null_fields(table_map allowed)
+{
+  if (!(allowed & used_tables()))
+    return false;
+  bool checked= false;
+  Item_equal_fields_iterator it(*this);
+  Item *item;
+  while ((item= it++))
+  {
+    if (~allowed & item->used_tables())
+      continue;
+    if ((with_const || checked) && !item->find_not_null_fields(allowed))
+      continue;
+    Item_equal_fields_iterator it1(*this);
+    Item *item1;
+    while ((item1= it1++) && item1 != item)
+    {
+      if (~allowed & item1->used_tables())
+        continue;
+      if (!item->find_not_null_fields(allowed) &&
+          !item1->find_not_null_fields(allowed))
+      {
+        checked= true;
+        break;
+      }
+    }
+  }
+  return false;
+}
+
+
+
+bool Item_equal::count_sargable_conds(void *arg)
+{
+  SELECT_LEX *sel= (SELECT_LEX *) arg;
+  uint m= equal_items.elements;
+  sel->cond_count+= m*(m-1);
+  return 0;
+}
+
+
+/**
+  @brief
+  Evaluate multiple equality
+
+  @details
+  The function evaluate multiple equality to a boolean value.
+  The function ignores non-constant items from the equal_items list.
+  The function returns 1 if all constant items from the list are equal. 
+  It returns 0 if there are unequal constant items in the list or 
+  one of the constant items is evaluated to NULL. 
+  
+  @notes 
+  Currently this function can be called only at the optimization
+  stage after the constant table substitution, since all Item_equals
+  are eliminated before the execution stage.
+  
+  @retval
+     0     multiple equality is always FALSE or NULL
+     1     otherwise
+*/
+
+longlong Item_equal::val_int()
+{
+  if (cond_false)
+    return 0;
+  if (cond_true)
+    return 1;
+  Item *item= get_const();
+  Item_equal_fields_iterator it(*this);
+  if (!item)
+    item= it++;
+  eval_item->store_value(item);
+  if ((null_value= item->null_value))
+    return 0;
+  while ((item= it++))
+  {
+    Field *field= it.get_curr_field();
+    /* Skip fields of tables that has not been read yet */
+    if (!field->table->status || (field->table->status & STATUS_NULL_ROW))
+    {
+      const int rc= eval_item->cmp(item);
+      if ((rc == TRUE) || (null_value= (rc == UNKNOWN)))
+        return 0;
+    }
+  }
+  return 1;
+}
+
+
+bool Item_equal::fix_length_and_dec(THD *thd)
+{
+  Item *item= get_first(NO_PARTICULAR_TAB, NULL);
+  const Type_handler *handler= item->type_handler();
+  eval_item= handler->make_cmp_item(thd, item->collation.collation);
+  return eval_item == NULL;
+}
+
+
+bool Item_equal::walk(Item_processor processor, bool walk_subquery, void *arg)
+{
+  Item *item;
+  Item_equal_fields_iterator it(*this);
+  while ((item= it++))
+  {
+    if (item->walk(processor, walk_subquery, arg))
+      return 1;
+  }
+  return Item_func::walk(processor, walk_subquery, arg);
+}
+
+
+Item *Item_equal::transform(THD *thd, Item_transformer transformer, uchar *arg)
+{
+  DBUG_ASSERT(!thd->stmt_arena->is_stmt_prepare());
+
+  Item *item;
+  Item_equal_fields_iterator it(*this);
+  while ((item= it++))
+  {
+    Item *new_item= item->transform(thd, transformer, arg);
+    if (!new_item)
+      return 0;
+
+    /*
+      THD::change_item_tree() should be called only if the tree was
+      really transformed, i.e. when a new item has been created.
+      Otherwise we'll be allocating a lot of unnecessary memory for
+      change records at each execution.
+    */
+    if (new_item != item)
+      thd->change_item_tree((Item **) it.ref(), new_item);
+  }
+  return Item_func::transform(thd, transformer, arg);
+}
+
+
+void Item_equal::print(String *str, enum_query_type query_type)
+{
+  if (cond_false)
+  {
+    str->append('0');
+    return;
+  }
+  str->append(func_name_cstring());
+  str->append('(');
+  List_iterator_fast<Item> it(equal_items);
+  Item *item;
+  item= it++;
+  item->print(str, query_type);
+  while ((item= it++))
+  {
+    str->append(',');
+    str->append(' ');
+    item->print(str, query_type);
+  }
+  str->append(')');
+}
+
+
+/*
+  @brief Get the first equal field of multiple equality.
+  @param[in] field   the field to get equal field to
+
+  @details Get the first field of multiple equality that is equal to the
+  given field. In order to make semi-join materialization strategy work
+  correctly we can't propagate equal fields from upper select to a
+  materialized semi-join.
+  Thus the fields is returned according to following rules:
+
+  1) If the given field belongs to a semi-join then the first field in
+     multiple equality which belong to the same semi-join is returned.
+     Otherwise NULL is returned.
+  2) If the given field doesn't belong to a semi-join then
+     the first field in the multiple equality that doesn't belong to any
+     semi-join is returned.
+     If all fields in the equality are belong to semi-join(s) then NULL
+     is returned.
+  3) If no field is given then the first field in the multiple equality
+     is returned without regarding whether it belongs to a semi-join or not.
+
+  @retval Found first field in the multiple equality.
+  @retval 0 if no field found.
+*/
+
+Item* Item_equal::get_first(JOIN_TAB *context, Item *field_item)
+{
+  Item_equal_fields_iterator it(*this);
+  Item *item;
+  if (!field_item)
+    return (it++);
+  Field *field= ((Item_field *) (field_item->real_item()))->field;
+
+  /*
+    Of all equal fields, return the first one we can use. Normally, this is the
+    field which belongs to the table that is the first in the join order.
+
+    There is one exception to this: When semi-join materialization strategy is
+    used, and the given field belongs to a table within the semi-join nest, we
+    must pick the first field in the semi-join nest.
+
+    Example: suppose we have a join order:
+
+       ot1 ot2  SJ-Mat(it1  it2  it3)  ot3
+
+    and equality ot2.col = it1.col = it2.col
+    If we're looking for best substitute for 'it2.col', we should pick it1.col
+    and not ot2.col.
+    
+    eliminate_item_equal() also has code that deals with equality substitution
+    in presence of SJM nests.
+  */
+
+  TABLE_LIST *emb_nest;
+  if (context != NO_PARTICULAR_TAB)
+    emb_nest= context->emb_sj_nest;
+  else
+    emb_nest= field->table->pos_in_table_list->embedding;
+
+  if (emb_nest && emb_nest->sj_mat_info && emb_nest->sj_mat_info->is_used)
+  {
+    /*
+      It's a field from an materialized semi-join. We can substitute it for
+       - a constant item 
+       - a field from the same semi-join
+       Find the first of such items:
+    */
+    while ((item= it++))
+    {
+      if (item->const_item() || 
+          it.get_curr_field()->table->pos_in_table_list->embedding == emb_nest)
+      {
+        /*
+          If we found given field then return NULL to avoid unnecessary
+          substitution.
+        */
+        return (item != field_item) ? item : NULL;
+      }
+    }
+  }
+  else
+  {
+    /*
+      The field is not in SJ-Materialization nest. We must return the first
+      field in the join order. The field may be inside a semi-join nest, i.e 
+      a join order may look like this:
+
+          SJ-Mat(it1  it2)  ot1  ot2
+
+      where we're looking what to substitute ot2.col for. In this case we must 
+      still return it1.col, here's a proof why:
+
+      First let's note that either it1.col or it2.col participates in 
+      subquery's IN-equality. It can't be otherwise, because materialization is
+      only applicable to uncorrelated subqueries, so the only way we could
+      infer "it1.col=ot1.col" is from the IN-equality. Ok, so IN-eqality has 
+      it1.col or it2.col on its inner side. it1.col is first such item in the
+      join order, so it's not possible for SJ-Mat to be
+      SJ-Materialization-lookup, it is SJ-Materialization-Scan. The scan part
+      of this strategy will unpack value of it1.col=it2.col into it1.col
+      (that's the first equal item inside the subquery), and we'll be able to
+      get it from there. qed.
+    */
+
+    return equal_items.head();
+  }
+  // Shouldn't get here.
+  DBUG_ASSERT(0);
+  return NULL;
+}
+
+
+longlong Item_func_dyncol_check::val_int()
+{
+  char buff[STRING_BUFFER_USUAL_SIZE];
+  String tmp(buff, sizeof(buff), &my_charset_bin);
+  DYNAMIC_COLUMN col;
+  String *str;
+  enum enum_dyncol_func_result rc;
+
+  str= args[0]->val_str(&tmp);
+  if (args[0]->null_value)
+    goto null;
+  col.length= str->length();
+  /* We do not change the string, so could do this trick */
+  col.str= (char *)str->ptr();
+  rc= mariadb_dyncol_check(&col);
+  if (rc < 0 && rc != ER_DYNCOL_FORMAT)
+  {
+    dynamic_column_error_message(rc);
+    goto null;
+  }
+  null_value= FALSE;
+  return rc == ER_DYNCOL_OK;
+
+null:
+  null_value= TRUE;
+  return 0;
+}
+
+longlong Item_func_dyncol_exists::val_int()
+{
+  char buff[STRING_BUFFER_USUAL_SIZE], nmstrbuf[11];
+  String tmp(buff, sizeof(buff), &my_charset_bin),
+         nmbuf(nmstrbuf, sizeof(nmstrbuf), system_charset_info);
+  DYNAMIC_COLUMN col;
+  String *str;
+  LEX_STRING buf, *name= NULL;
+  ulonglong num= 0;
+  enum enum_dyncol_func_result rc;
+
+  if (args[1]->result_type() == INT_RESULT)
+    num= args[1]->val_int();
+  else
+  {
+    String *nm= args[1]->val_str(&nmbuf);
+    if (!nm || args[1]->null_value)
+    {
+      null_value= 1;
+      return 1;
+    }
+    if (my_charset_same(nm->charset(), DYNCOL_UTF))
+    {
+      buf.str= (char *) nm->ptr();
+      buf.length= nm->length();
+    }
+    else
+    {
+      uint strlen= nm->length() * DYNCOL_UTF->mbmaxlen + 1;
+      uint dummy_errors;
+      buf.str= (char *) current_thd->alloc(strlen);
+      if (buf.str)
+      {
+        buf.length=
+          copy_and_convert(buf.str, strlen, DYNCOL_UTF,
+                           nm->ptr(), nm->length(), nm->charset(),
+                           &dummy_errors);
+      }
+      else
+        buf.length= 0;
+    }
+    name= &buf;
+  }
+  str= args[0]->val_str(&tmp);
+  if (args[0]->null_value || args[1]->null_value || num > UINT_MAX16)
+    goto null;
+  col.length= str->length();
+  /* We do not change the string, so could do this trick */
+  col.str= (char *)str->ptr();
+  rc= ((name == NULL) ?
+       mariadb_dyncol_exists_num(&col, (uint) num) :
+       mariadb_dyncol_exists_named(&col, name));
+  if (rc < 0)
+  {
+    dynamic_column_error_message(rc);
+    goto null;
+  }
+  null_value= FALSE;
+  return rc == ER_DYNCOL_YES;
+
+null:
+  null_value= TRUE;
+  return 0;
+}
+
+
+Item_bool_rowready_func2 *Eq_creator::create(THD *thd, Item *a, Item *b) const
+{
+  return new(thd->mem_root) Item_func_eq(thd, a, b);
+}
+
+
+Item_bool_rowready_func2* Eq_creator::create_swap(THD *thd, Item *a, Item *b) const
+{
+  return new(thd->mem_root) Item_func_eq(thd, b, a);
+}
+
+
+Item_bool_rowready_func2* Ne_creator::create(THD *thd, Item *a, Item *b) const
+{
+  return new(thd->mem_root) Item_func_ne(thd, a, b);
+}
+
+
+Item_bool_rowready_func2* Ne_creator::create_swap(THD *thd, Item *a, Item *b) const
+{
+  return new(thd->mem_root) Item_func_ne(thd, b, a);
+}
+
+
+Item_bool_rowready_func2* Gt_creator::create(THD *thd, Item *a, Item *b) const
+{
+  return new(thd->mem_root) Item_func_gt(thd, a, b);
+}
+
+
+Item_bool_rowready_func2* Gt_creator::create_swap(THD *thd, Item *a, Item *b) const
+{
+  return new(thd->mem_root) Item_func_lt(thd, b, a);
+}
+
+
+Item_bool_rowready_func2* Lt_creator::create(THD *thd, Item *a, Item *b) const
+{
+  return new(thd->mem_root) Item_func_lt(thd, a, b);
+}
+
+
+Item_bool_rowready_func2* Lt_creator::create_swap(THD *thd, Item *a, Item *b) const
+{
+  return new(thd->mem_root) Item_func_gt(thd, b, a);
+}
+
+
+Item_bool_rowready_func2* Ge_creator::create(THD *thd, Item *a, Item *b) const
+{
+  return new(thd->mem_root) Item_func_ge(thd, a, b);
+}
+
+
+Item_bool_rowready_func2* Ge_creator::create_swap(THD *thd, Item *a, Item *b) const
+{
+  return new(thd->mem_root) Item_func_le(thd, b, a);
+}
+
+
+Item_bool_rowready_func2* Le_creator::create(THD *thd, Item *a, Item *b) const
+{
+  return new(thd->mem_root) Item_func_le(thd, a, b);
+}
+
+
+Item_bool_rowready_func2* Le_creator::create_swap(THD *thd, Item *a, Item *b) const
+{
+  return new(thd->mem_root) Item_func_ge(thd, b, a);
+}
+
+
+bool
+Item_equal::excl_dep_on_grouping_fields(st_select_lex *sel)
+{
+  Item_equal_fields_iterator it(*this);
+  Item *item;
+
+  while ((item=it++))
+  {
+    if (item->excl_dep_on_grouping_fields(sel))
+    {
+      set_extraction_flag(MARKER_FULL_EXTRACTION);
+      return true;
+    }
+  }
+  return false;
+}
+
+
+/**
+  @brief
+    Transform multiple equality into list of equalities
+
+  @param thd         the thread handle
+  @param equalities  the list where created equalities are stored
+  @param checker     the checker callback function to be applied to the nodes
+                     of the tree of the object to check if multiple equality
+                     elements can be used to create equalities
+  @param arg         parameter to be passed to the checker
+  @param clone_const true <=> clone the constant member if there is any
+
+  @details
+    How the method works on examples:
+
+    Example 1:
+    It takes MULT_EQ(x,a,b) and tries to create from its elements a set of
+    equalities {(x=a),(x=b)}.
+
+    Example 2:
+    It takes MULT_EQ(1,a,b) and tries to create from its elements a set of
+    equalities {(a=1),(a=b)}.
+
+    How it is done:
+
+    1. If there is a constant member c the first non-constant member x for
+       which the function checker returns true is taken and an item for
+       the equality x=c is created. When constructing the equality item
+       the left part of the equality is always taken as a clone of x while
+       the right part is taken as a clone of c only if clone_const == true.
+
+    2. After this all equalities of the form x=a (where x designates the first
+       non-constant member for which checker returns true and a is some other
+       such member of the multiplle equality) are created. When constructing
+       an equality item both its parts are taken as clones of x and a.
+    
+       Suppose in the examples above that for 'x', 'a', and 'b' the function
+       checker returns true.
+
+       Example 1:
+         the equality (x=a) is built
+         the equality (x=b) is built
+
+       Example 2:
+         the equality (a=1) is built
+         the equality (a=b) is built
+
+    3. As a result we get a set of equalities built with the elements of
+       this multiple equality. They are saved in the equality list.
+
+       Example 1:
+       {(x=a),(x=b)}
+
+       Example 2:
+       {(a=1),(a=b)}
+
+  @note
+    This method is called for condition pushdown into materialized
+    derived table/view, and IN subquery, and pushdown from HAVING into WHERE.
+    When it is called for pushdown from HAVING the empty checker is passed.
+    This is because in this case the elements of the multiple equality don't
+    need to be  checked if they can be used to build equalities: either all
+    equalities can be pushed or none of them can be pushed.
+    When the function is called for pushdown from HAVING the value of the
+    parameter clone_const is always false. In other cases it's always true.
+
+  @retval true   if an error occurs
+  @retval false  otherwise
+*/
+
+bool Item_equal::create_pushable_equalities(THD *thd,
+                                            List<Item> *equalities,
+                                            Pushdown_checker checker,
+                                            uchar *arg,
+                                            bool clone_const)
+{
+  Item *item;
+  Item *left_item= NULL;
+  Item *right_item = get_const();
+  Item_equal_fields_iterator it(*this);
+
+  while ((item=it++))
+  {
+    left_item= item;
+    if (checker && !((item->*checker) (arg)))
+      continue;
+    break;
+  }
+
+  if (!left_item)
+    return false;
+
+  if (right_item)
+  {
+    Item_func_eq *eq= 0;
+    Item *left_item_clone= left_item->build_clone(thd);
+    Item *right_item_clone= !clone_const ?
+                            right_item : right_item->build_clone(thd);
+    if (!left_item_clone || !right_item_clone)
+      return true;
+    eq= new (thd->mem_root) Item_func_eq(thd,
+                                         left_item_clone,
+                                         right_item_clone);
+    if (!eq ||  equalities->push_back(eq, thd->mem_root))
+      return true;
+    if (!clone_const)
+    {
+      /*
+        Also set IMMUTABLE_FL for any sub-items of the right_item.
+        This is needed to prevent Item::cleanup_excluding_immutables_processor
+        from peforming cleanup of the sub-items and so creating an item tree
+        where a fixed item has non-fixed items inside it.
+      */
+      int16 new_flag= MARKER_IMMUTABLE;
+      right_item->walk(&Item::set_extraction_flag_processor, false,
+                       (void*)&new_flag);
+    }
+  }
+
+  while ((item=it++))
+  {
+    if (checker && !((item->*checker) (arg)))
+      continue;
+    Item_func_eq *eq= 0;
+    Item *left_item_clone= left_item->build_clone(thd);
+    Item *right_item_clone= item->build_clone(thd);
+    if (!(left_item_clone && right_item_clone))
+      return true;
+    left_item_clone->set_item_equal(NULL);
+    right_item_clone->set_item_equal(NULL);
+    eq= new (thd->mem_root) Item_func_eq(thd,
+                                         right_item_clone,
+                                         left_item_clone);
+    if (!eq || equalities->push_back(eq, thd->mem_root))
+      return true;
+  }
+  return false;
+}
+
+
+/**
+  Transform multiple equality into the AND condition of equalities.
+
+  Example:
+  MULT_EQ(x,a,b)
+  =>
+  (x=a) AND (x=b)
+
+  Equalities are built in Item_equal::create_pushable_equalities() method
+  using elements of this multiple equality. The result of this method is
+  saved in an equality list.
+  This method returns the condition where the elements of the equality list
+  are anded.
+*/
+
+Item *Item_equal::multiple_equality_transformer(THD *thd, uchar *arg)
+{
+  List<Item> equalities;
+  if (create_pushable_equalities(thd, &equalities, 0, 0, false))
+    return 0;
+
+  switch (equalities.elements)
+  {
+  case 0:
+    return 0;
+  case 1:
+    return equalities.head();
+    break;
+  default:
+    return new (thd->mem_root) Item_cond_and(thd, equalities);
+    break;
+  }
+}