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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-05-04 18:07:14 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-05-04 18:07:14 +0000
commita175314c3e5827eb193872241446f2f8f5c9d33c (patch)
treecd3d60ca99ae00829c52a6ca79150a5b6e62528b /sql/sql_tvc.cc
parentInitial commit. (diff)
downloadmariadb-10.5-a175314c3e5827eb193872241446f2f8f5c9d33c.tar.xz
mariadb-10.5-a175314c3e5827eb193872241446f2f8f5c9d33c.zip
Adding upstream version 1:10.5.12.upstream/1%10.5.12upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to '')
-rw-r--r--sql/sql_tvc.cc1187
1 files changed, 1187 insertions, 0 deletions
diff --git a/sql/sql_tvc.cc b/sql/sql_tvc.cc
new file mode 100644
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--- /dev/null
+++ b/sql/sql_tvc.cc
@@ -0,0 +1,1187 @@
+/* Copyright (c) 2017, 2020, 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 St, Fifth Floor, Boston, MA 02110-1301 USA */
+
+#include "mariadb.h"
+#include "sql_list.h"
+#include "sql_tvc.h"
+#include "sql_class.h"
+#include "opt_range.h"
+#include "sql_select.h"
+#include "sql_explain.h"
+#include "sql_parse.h"
+#include "sql_cte.h"
+#include "my_json_writer.h"
+
+
+/**
+ @brief
+ Walk through all VALUES items.
+ @param
+ @param processor - the processor to call for each Item
+ @param walk_qubquery - if should dive into subquery items
+ @param argument - the argument to pass recursively
+ @retval
+ true on error
+ false on success
+*/
+bool table_value_constr::walk_values(Item_processor processor,
+ bool walk_subquery,
+ void *argument)
+{
+ List_iterator_fast<List_item> list_item_it(lists_of_values);
+ while (List_item *list= list_item_it++)
+ {
+ List_iterator_fast<Item> item_it(*list);
+ while (Item *item= item_it++)
+ {
+ if (item->walk(&Item::unknown_splocal_processor, false, argument))
+ return true;
+ }
+ }
+ return false;
+}
+
+
+/**
+ @brief
+ Fix fields for TVC values
+
+ @param
+ @param thd The context of the statement
+ @param li The iterator on the list of lists
+
+ @details
+ Call fix_fields procedure for TVC values.
+
+ @retval
+ true if an error was reported
+ false otherwise
+*/
+
+bool fix_fields_for_tvc(THD *thd, List_iterator_fast<List_item> &li)
+{
+ DBUG_ENTER("fix_fields_for_tvc");
+ List_item *lst;
+ li.rewind();
+
+ while ((lst= li++))
+ {
+ List_iterator<Item> it(*lst);
+ Item *item;
+
+ while ((item= it++))
+ {
+ /*
+ Some items have already been fixed.
+ For example Item_splocal items get fixed in
+ Item_splocal::append_for_log(), which is called from subst_spvars()
+ while replacing their values to NAME_CONST()s.
+ So fix only those that have not been.
+ */
+ if (item->fix_fields_if_needed_for_scalar(thd, it.ref()) ||
+ item->check_is_evaluable_expression_or_error())
+ DBUG_RETURN(true);
+ }
+ }
+ DBUG_RETURN(false);
+}
+
+
+/**
+ @brief
+ Defines types of matrix columns elements where matrix rows are defined by
+ some lists of values.
+
+ @param
+ @param thd The context of the statement
+ @param li The iterator on the list of lists
+ @param holders The structure where types of matrix columns are stored
+ @param first_list_el_count Count of the list values. It should be the same
+ for each list of lists elements. It contains
+ number of elements of the first list from list of
+ lists.
+
+ @details
+ For each list list_a from list of lists the procedure gets its elements
+ types and aggregates them with the previous ones stored in holders. If
+ list_a is the first one in the list of lists its elements types are put in
+ holders. The errors can be reported when count of list_a elements is
+ different from the first_list_el_count. Also error can be reported whe
+ n aggregation can't be made.
+
+ @retval
+ true if an error was reported
+ false otherwise
+*/
+
+bool join_type_handlers_for_tvc(THD *thd, List_iterator_fast<List_item> &li,
+ Type_holder *holders, uint first_list_el_count)
+{
+ DBUG_ENTER("join_type_handlers_for_tvc");
+ List_item *lst;
+ li.rewind();
+ bool first= true;
+
+ while ((lst= li++))
+ {
+ List_iterator_fast<Item> it(*lst);
+ Item *item;
+
+ if (first_list_el_count != lst->elements)
+ {
+ my_message(ER_WRONG_NUMBER_OF_VALUES_IN_TVC,
+ ER_THD(thd, ER_WRONG_NUMBER_OF_VALUES_IN_TVC),
+ MYF(0));
+ DBUG_RETURN(true);
+ }
+ for (uint pos= 0; (item=it++); pos++)
+ {
+ const Type_handler *item_type_handler= item->real_type_handler();
+ if (first)
+ holders[pos].set_handler(item_type_handler);
+ else if (holders[pos].aggregate_for_result(item_type_handler))
+ {
+ my_error(ER_ILLEGAL_PARAMETER_DATA_TYPES2_FOR_OPERATION, MYF(0),
+ holders[pos].type_handler()->name().ptr(),
+ item_type_handler->name().ptr(),
+ "TABLE VALUE CONSTRUCTOR");
+ DBUG_RETURN(true);
+ }
+ }
+ first= false;
+ }
+ DBUG_RETURN(false);
+}
+
+
+/**
+ @brief
+ Define attributes of matrix columns elements where matrix rows are defined
+ by some lists of values.
+
+ @param
+ @param thd The context of the statement
+ @param li The iterator on the list of lists
+ @param holders The structure where names of matrix columns are stored
+ @param count_of_lists Count of list of lists elements
+ @param first_list_el_count Count of the list values. It should be the same
+ for each list of lists elements. It contains
+ number of elements of the first list from list
+ of lists.
+
+ @details
+ For each list list_a from list of lists the procedure gets its elements
+ attributes and aggregates them with the previous ones stored in holders.
+ The errors can be reported when aggregation can't be made.
+
+ @retval
+ true if an error was reported
+ false otherwise
+*/
+
+bool get_type_attributes_for_tvc(THD *thd,
+ List_iterator_fast<List_item> &li,
+ Type_holder *holders, uint count_of_lists,
+ uint first_list_el_count)
+{
+ DBUG_ENTER("get_type_attributes_for_tvc");
+ List_item *lst;
+ li.rewind();
+
+ for (uint pos= 0; pos < first_list_el_count; pos++)
+ {
+ if (holders[pos].alloc_arguments(thd, count_of_lists))
+ DBUG_RETURN(true);
+ }
+
+ while ((lst= li++))
+ {
+ List_iterator_fast<Item> it(*lst);
+ Item *item;
+ for (uint holder_pos= 0 ; (item= it++); holder_pos++)
+ {
+ DBUG_ASSERT(item->is_fixed());
+ holders[holder_pos].add_argument(item);
+ }
+ }
+
+ for (uint pos= 0; pos < first_list_el_count; pos++)
+ {
+ if (holders[pos].aggregate_attributes(thd))
+ DBUG_RETURN(true);
+ }
+ DBUG_RETURN(false);
+}
+
+
+/**
+ @brief
+ Prepare of TVC
+
+ @param
+ @param thd The context of the statement
+ @param sl The select where this TVC is defined
+ @param tmp_result Structure that contains the information
+ about where to send the result of the query
+ @param unit_arg The union where sl is defined
+
+ @details
+ Gets types and attributes of values of this TVC that will be used
+ for temporary table creation for this TVC. It creates Item_type_holders
+ for each element of the first list from list of lists (VALUES from tvc),
+ using its elements name, defined type and attribute.
+
+ @retval
+ true if an error was reported
+ false otherwise
+*/
+
+bool table_value_constr::prepare(THD *thd, SELECT_LEX *sl,
+ select_result *tmp_result,
+ st_select_lex_unit *unit_arg)
+{
+ DBUG_ENTER("table_value_constr::prepare");
+ select_lex->in_tvc= true;
+ List_iterator_fast<List_item> li(lists_of_values);
+
+ List_item *first_elem= li++;
+ uint cnt= first_elem->elements;
+ Type_holder *holders;
+
+ if (cnt == 0)
+ {
+ my_error(ER_EMPTY_ROW_IN_TVC, MYF(0));
+ DBUG_RETURN(true);
+ }
+
+ if (fix_fields_for_tvc(thd, li))
+ DBUG_RETURN(true);
+
+ if (!(holders= new (thd->stmt_arena->mem_root) Type_holder[cnt]) ||
+ join_type_handlers_for_tvc(thd, li, holders, cnt) ||
+ get_type_attributes_for_tvc(thd, li, holders,
+ lists_of_values.elements, cnt))
+ DBUG_RETURN(true);
+
+ List_iterator_fast<Item> it(*first_elem);
+ Item *item;
+ Query_arena *arena, backup;
+ arena=thd->activate_stmt_arena_if_needed(&backup);
+
+ sl->item_list.empty();
+ for (uint pos= 0; (item= it++); pos++)
+ {
+ /* Error's in 'new' will be detected after loop */
+ Item_type_holder *new_holder= new (thd->mem_root)
+ Item_type_holder(thd, item, holders[pos].type_handler(),
+ &holders[pos]/*Type_all_attributes*/,
+ holders[pos].get_maybe_null());
+ sl->item_list.push_back(new_holder);
+ }
+ if (arena)
+ thd->restore_active_arena(arena, &backup);
+
+ if (unlikely(thd->is_fatal_error))
+ DBUG_RETURN(true); // out of memory
+
+ result= tmp_result;
+
+ if (result && result->prepare(sl->item_list, unit_arg))
+ DBUG_RETURN(true);
+
+ /*
+ setup_order() for a TVC is not called when the following is true
+ (thd->lex->context_analysis_only & CONTEXT_ANALYSIS_ONLY_VIEW)
+ */
+
+ thd->where="order clause";
+ ORDER *order= sl->order_list.first;
+ for (; order; order=order->next)
+ {
+ Item *order_item= *order->item;
+ if (order_item->is_order_clause_position())
+ {
+ uint count= 0;
+ if (order->counter_used)
+ count= order->counter; // counter was once resolved
+ else
+ count= (uint) order_item->val_int();
+ if (!count || count > first_elem->elements)
+ {
+ my_error(ER_BAD_FIELD_ERROR, MYF(0),
+ order_item->full_name(), thd->where);
+ DBUG_RETURN(true);
+ }
+ order->in_field_list= 1;
+ order->counter= count;
+ order->counter_used= 1;
+ }
+ }
+
+ select_lex->in_tvc= false;
+ DBUG_RETURN(false);
+}
+
+
+/**
+ Save Query Plan Footprint
+*/
+
+int table_value_constr::save_explain_data_intern(THD *thd,
+ Explain_query *output)
+{
+ const char *message= "No tables used";
+ DBUG_ENTER("table_value_constr::save_explain_data_intern");
+ DBUG_PRINT("info", ("Select %p, type %s, message %s",
+ select_lex, select_lex->type,
+ message));
+ DBUG_ASSERT(have_query_plan == QEP_AVAILABLE);
+
+ /* There should be no attempts to save query plans for merged selects */
+ DBUG_ASSERT(!select_lex->master_unit()->derived ||
+ select_lex->master_unit()->derived->is_materialized_derived() ||
+ select_lex->master_unit()->derived->is_with_table());
+
+ explain= new (output->mem_root) Explain_select(output->mem_root,
+ thd->lex->analyze_stmt);
+ if (!explain)
+ DBUG_RETURN(1);
+
+ select_lex->set_explain_type(true);
+
+ explain->select_id= select_lex->select_number;
+ explain->select_type= select_lex->type;
+ explain->linkage= select_lex->get_linkage();
+ explain->using_temporary= false;
+ explain->using_filesort= false;
+ /* Setting explain->message means that all other members are invalid */
+ explain->message= message;
+
+ if (select_lex->master_unit()->derived)
+ explain->connection_type= Explain_node::EXPLAIN_NODE_DERIVED;
+
+ for (SELECT_LEX_UNIT *unit= select_lex->first_inner_unit();
+ unit;
+ unit= unit->next_unit())
+ {
+ explain->add_child(unit->first_select()->select_number);
+ }
+
+ output->add_node(explain);
+
+ if (select_lex->is_top_level_node())
+ output->query_plan_ready();
+
+ DBUG_RETURN(0);
+}
+
+
+/**
+ Optimization of TVC
+*/
+
+bool table_value_constr::optimize(THD *thd)
+{
+ create_explain_query_if_not_exists(thd->lex, thd->mem_root);
+ have_query_plan= QEP_AVAILABLE;
+
+ if (select_lex->select_number != UINT_MAX &&
+ select_lex->select_number != INT_MAX /* this is not a UNION's "fake select */ &&
+ have_query_plan != QEP_NOT_PRESENT_YET &&
+ thd->lex->explain && // for "SET" command in SPs.
+ (!thd->lex->explain->get_select(select_lex->select_number)))
+ {
+ if (save_explain_data_intern(thd, thd->lex->explain))
+ return true;
+ }
+
+ if (select_lex->optimize_unflattened_subqueries(true))
+ return true;
+
+ return false;
+}
+
+
+/**
+ Execute of TVC
+*/
+
+bool table_value_constr::exec(SELECT_LEX *sl)
+{
+ DBUG_ENTER("table_value_constr::exec");
+ List_iterator_fast<List_item> li(lists_of_values);
+ List_item *elem;
+ ha_rows send_records= 0;
+
+ if (select_options & SELECT_DESCRIBE)
+ DBUG_RETURN(false);
+
+ if (result->send_result_set_metadata(sl->item_list,
+ Protocol::SEND_NUM_ROWS |
+ Protocol::SEND_EOF))
+ {
+ DBUG_RETURN(true);
+ }
+
+ while ((elem= li++))
+ {
+ if (send_records >= sl->master_unit()->lim.get_select_limit())
+ break;
+ int rc=
+ result->send_data_with_check(*elem, sl->master_unit(), send_records);
+ if (!rc)
+ send_records++;
+ else if (rc > 0)
+ DBUG_RETURN(true);
+ }
+
+ if (result->send_eof())
+ DBUG_RETURN(true);
+
+ DBUG_RETURN(false);
+}
+
+
+/**
+ @brief
+ Print list
+
+ @param str The reference on the string representation of the list
+ @param list The list that needed to be print
+ @param query_type The mode of printing
+
+ @details
+ The method saves a string representation of list in the
+ string str.
+*/
+
+void print_list_item(String *str, List_item *list,
+ enum_query_type query_type)
+{
+ bool is_first_elem= true;
+ List_iterator_fast<Item> it(*list);
+ Item *item;
+
+ str->append('(');
+
+ while ((item= it++))
+ {
+ if (is_first_elem)
+ is_first_elem= false;
+ else
+ str->append(',');
+
+ item->print(str, query_type);
+ }
+
+ str->append(')');
+}
+
+
+/**
+ @brief
+ Print this TVC
+
+ @param thd The context of the statement
+ @param str The reference on the string representation of this TVC
+ @param query_type The mode of printing
+
+ @details
+ The method saves a string representation of this TVC in the
+ string str.
+*/
+
+void table_value_constr::print(THD *thd, String *str,
+ enum_query_type query_type)
+{
+ DBUG_ASSERT(thd);
+
+ str->append(STRING_WITH_LEN("values "));
+
+ bool is_first_elem= true;
+ List_iterator_fast<List_item> li(lists_of_values);
+ List_item *list;
+
+ while ((list= li++))
+ {
+ if (is_first_elem)
+ is_first_elem= false;
+ else
+ str->append(',');
+
+ print_list_item(str, list, query_type);
+ }
+ if (select_lex->order_list.elements)
+ {
+ str->append(STRING_WITH_LEN(" order by "));
+ select_lex->print_order(str, select_lex->order_list.first, query_type);
+ }
+ select_lex->print_limit(thd, str, query_type);
+}
+
+
+/**
+ @brief
+ Create list of lists for TVC from the list of this IN predicate
+
+ @param thd The context of the statement
+ @param values TVC list of values
+
+ @details
+ The method uses the list of values of this IN predicate to build
+ an equivalent list of values that can be used in TVC.
+
+ E.g.:
+
+ <value_list> = 5,2,7
+ <transformed_value_list> = (5),(2),(7)
+
+ <value_list> = (5,2),(7,1)
+ <transformed_value_list> = (5,2),(7,1)
+
+ @retval
+ false if the method succeeds
+ true otherwise
+*/
+
+bool Item_func_in::create_value_list_for_tvc(THD *thd,
+ List< List<Item> > *values)
+{
+ bool is_list_of_rows= args[1]->type() == Item::ROW_ITEM;
+
+ for (uint i=1; i < arg_count; i++)
+ {
+ char col_name[8];
+ List<Item> *tvc_value;
+ if (!(tvc_value= new (thd->mem_root) List<Item>()))
+ return true;
+
+ if (is_list_of_rows)
+ {
+ Item_row *row_list= (Item_row *)(args[i]);
+
+ for (uint j=0; j < row_list->cols(); j++)
+ {
+ if (i == 1)
+ {
+ sprintf(col_name, "_col_%i", j+1);
+ row_list->element_index(j)->set_name(thd, col_name, strlen(col_name),
+ thd->charset());
+ }
+ if (tvc_value->push_back(row_list->element_index(j),
+ thd->mem_root))
+ return true;
+ }
+ }
+ else
+ {
+ if (i == 1)
+ {
+ sprintf(col_name, "_col_%i", 1);
+ args[i]->set_name(thd, col_name, strlen(col_name), thd->charset());
+ }
+ if (tvc_value->push_back(args[i]->real_item()))
+ return true;
+ }
+
+ if (values->push_back(tvc_value, thd->mem_root))
+ return true;
+ }
+ return false;
+}
+
+
+/**
+ @brief
+ Create name for the derived table defined by TVC
+
+ @param thd The context of the statement
+ @param parent_select The SELECT where derived table is used
+ @param alias The returned created name
+
+ @details
+ Create name for the derived table using current TVC number
+ for this parent_select stored in parent_select
+
+ @retval
+ true if creation fails
+ false otherwise
+*/
+
+static bool create_tvc_name(THD *thd, st_select_lex *parent_select,
+ LEX_CSTRING *alias)
+{
+ char buff[6];
+
+ alias->length= my_snprintf(buff, sizeof(buff),
+ "tvc_%u",
+ parent_select ? parent_select->curr_tvc_name : 0);
+ alias->str= thd->strmake(buff, alias->length);
+ if (!alias->str)
+ return true;
+
+ return false;
+}
+
+
+/**
+ @brief
+ Check whether TVC used in unit is to be wrapped into select
+
+ @details
+ TVC used in unit that contains more than one members is to be wrapped
+ into select if it is tailed with ORDER BY ... LIMIT n [OFFSET m]
+
+ @retval
+ true if TVC is to be wrapped
+ false otherwise
+*/
+
+bool table_value_constr::to_be_wrapped_as_with_tail()
+{
+ return select_lex->master_unit()->first_select()->next_select() &&
+ select_lex->order_list.elements && select_lex->explicit_limit;
+}
+
+
+/**
+ @brief
+ Wrap table value constructor into a select
+
+ @param thd The context handler
+ @param tvc_sl The TVC to wrap
+ @parent_select The parent select if tvc_sl used in a subquery
+
+ @details
+ The function wraps the TVC tvc_sl into a select:
+ the function transforms the TVC of the form VALUES (v1), ... (vn) into
+ the select of the form
+ SELECT * FROM (VALUES (v1), ... (vn)) tvc_x
+
+ @retval pointer to the result of of the transformation if successful
+ NULL - otherwise
+*/
+
+static
+st_select_lex *wrap_tvc(THD *thd, st_select_lex *tvc_sl,
+ st_select_lex *parent_select)
+{
+ LEX *lex= thd->lex;
+ select_result *save_result= lex->result;
+ uint8 save_derived_tables= lex->derived_tables;
+ thd->lex->result= NULL;
+
+ Query_arena backup;
+ Query_arena *arena= thd->activate_stmt_arena_if_needed(&backup);
+
+ Item *item;
+ SELECT_LEX *wrapper_sl;
+ SELECT_LEX_UNIT *derived_unit;
+
+ /*
+ Create SELECT_LEX wrapper_sl of the select used in the result
+ of the transformation
+ */
+ if (!(wrapper_sl= new (thd->mem_root) SELECT_LEX()))
+ goto err;
+ wrapper_sl->select_number= ++thd->lex->stmt_lex->current_select_number;
+ wrapper_sl->parent_lex= lex; /* Used in init_query. */
+ wrapper_sl->init_query();
+ wrapper_sl->init_select();
+
+ wrapper_sl->nest_level= tvc_sl->nest_level;
+ wrapper_sl->parsing_place= tvc_sl->parsing_place;
+ wrapper_sl->set_linkage(tvc_sl->get_linkage());
+ wrapper_sl->exclude_from_table_unique_test=
+ tvc_sl->exclude_from_table_unique_test;
+
+ lex->current_select= wrapper_sl;
+ item= new (thd->mem_root) Item_field(thd, &wrapper_sl->context,
+ star_clex_str);
+ if (item == NULL || add_item_to_list(thd, item))
+ goto err;
+ (wrapper_sl->with_wild)++;
+
+ /* Include the newly created select into the global list of selects */
+ wrapper_sl->include_global((st_select_lex_node**)&lex->all_selects_list);
+
+ /* Substitute select node used of TVC for the newly created select */
+ tvc_sl->substitute_in_tree(wrapper_sl);
+
+ /*
+ Create a unit for the substituted select used for TVC and attach it
+ to the the wrapper select wrapper_sl as the only unit. The created
+ unit is the unit for the derived table tvc_x of the transformation.
+ */
+ if (!(derived_unit= new (thd->mem_root) SELECT_LEX_UNIT()))
+ goto err;
+ derived_unit->init_query();
+ derived_unit->thd= thd;
+ derived_unit->include_down(wrapper_sl);
+
+ /*
+ Attach the select used of TVC as the only slave to the unit for
+ the derived table tvc_x of the transformation
+ */
+ derived_unit->add_slave(tvc_sl);
+ tvc_sl->set_linkage(DERIVED_TABLE_TYPE);
+
+ /*
+ Generate the name of the derived table created for TVC and
+ add it to the FROM list of the wrapping select
+ */
+ Table_ident *ti;
+ LEX_CSTRING alias;
+ TABLE_LIST *derived_tab;
+ if (!(ti= new (thd->mem_root) Table_ident(derived_unit)) ||
+ create_tvc_name(thd, parent_select, &alias))
+ goto err;
+ if (!(derived_tab=
+ wrapper_sl->add_table_to_list(thd,
+ ti, &alias, 0,
+ TL_READ, MDL_SHARED_READ)))
+ goto err;
+ wrapper_sl->add_joined_table(derived_tab);
+ wrapper_sl->add_where_field(derived_unit->first_select());
+ wrapper_sl->context.table_list= wrapper_sl->table_list.first;
+ wrapper_sl->context.first_name_resolution_table= wrapper_sl->table_list.first;
+ wrapper_sl->table_list.first->derived_type= DTYPE_TABLE | DTYPE_MATERIALIZE;
+ lex->derived_tables|= DERIVED_SUBQUERY;
+
+ if (arena)
+ thd->restore_active_arena(arena, &backup);
+ lex->result= save_result;
+ return wrapper_sl;
+
+err:
+ if (arena)
+ thd->restore_active_arena(arena, &backup);
+ lex->result= save_result;
+ lex->derived_tables= save_derived_tables;
+ return 0;
+}
+
+
+/**
+ @brief
+ Wrap TVC with ORDER BY ... LIMIT tail into a select
+
+ @param thd The context handler
+ @param tvc_sl The TVC to wrap
+
+ @details
+ The function wraps the TVC tvc_sl into a select:
+ the function transforms the TVC with tail of the form
+ VALUES (v1), ... (vn) ORDER BY ... LIMIT n [OFFSET m]
+ into the select with the same tail of the form
+ SELECT * FROM (VALUES (v1), ... (vn)) tvc_x
+ ORDER BY ... LIMIT n [OFFSET m]
+
+ @retval pointer to the result of of the transformation if successful
+ NULL - otherwise
+*/
+
+st_select_lex *wrap_tvc_with_tail(THD *thd, st_select_lex *tvc_sl)
+{
+ st_select_lex *wrapper_sl= wrap_tvc(thd, tvc_sl, NULL);
+ if (!wrapper_sl)
+ return NULL;
+
+ wrapper_sl->order_list= tvc_sl->order_list;
+ wrapper_sl->select_limit= tvc_sl->select_limit;
+ wrapper_sl->offset_limit= tvc_sl->offset_limit;
+ wrapper_sl->braces= tvc_sl->braces;
+ wrapper_sl->explicit_limit= tvc_sl->explicit_limit;
+ tvc_sl->order_list.empty();
+ tvc_sl->select_limit= NULL;
+ tvc_sl->offset_limit= NULL;
+ tvc_sl->braces= 0;
+ tvc_sl->explicit_limit= false;
+ if (tvc_sl->select_number == 1)
+ {
+ tvc_sl->select_number= wrapper_sl->select_number;
+ wrapper_sl->select_number= 1;
+ }
+ if (tvc_sl->master_unit()->union_distinct == tvc_sl)
+ {
+ wrapper_sl->master_unit()->union_distinct= wrapper_sl;
+ }
+ wrapper_sl->distinct= tvc_sl->distinct;
+ thd->lex->current_select= wrapper_sl;
+ return wrapper_sl;
+}
+
+
+/**
+ @brief
+ Wrap TVC in a subselect into a select
+
+ @param thd The context handler
+ @param tvc_sl The TVC to wrap
+
+ @details
+ The function wraps the TVC tvc_sl used in a subselect into a select
+ the function transforms the TVC of the form VALUES (v1), ... (vn)
+ into the select the form
+ SELECT * FROM (VALUES (v1), ... (vn)) tvc_x
+ and replaces the subselect with the result of the transformation.
+
+ @retval wrapping select if successful
+ 0 otherwise
+*/
+
+st_select_lex *
+Item_subselect::wrap_tvc_into_select(THD *thd, st_select_lex *tvc_sl)
+{
+ LEX *lex= thd->lex;
+ /* SELECT_LEX object where the transformation is performed */
+ SELECT_LEX *parent_select= lex->current_select;
+ SELECT_LEX *wrapper_sl= wrap_tvc(thd, tvc_sl, parent_select);
+ if (wrapper_sl)
+ {
+ if (engine->engine_type() == subselect_engine::SINGLE_SELECT_ENGINE)
+ ((subselect_single_select_engine *) engine)->change_select(wrapper_sl);
+ }
+ lex->current_select= parent_select;
+ return wrapper_sl;
+}
+
+
+/*
+ @brief
+ Check whether the items are of comparable type or not
+
+ @details
+ This check are done because materialization is not performed
+ if the left expr and right expr are of the same types.
+ @see subquery_types_allow_materialization()
+
+ @retval
+ 0 comparable
+ 1 not comparable
+*/
+
+static bool cmp_row_types(Item* item1, Item* item2)
+{
+ uint n= item1->cols();
+ if (item2->check_cols(n))
+ return true;
+
+ for (uint i=0; i < n; i++)
+ {
+ Item *inner= item1->element_index(i);
+ Item *outer= item2->element_index(i);
+ if (!inner->type_handler()->subquery_type_allows_materialization(inner,
+ outer,
+ true))
+ return true;
+ }
+ return false;
+}
+
+
+/**
+ @brief
+ Transform IN predicate into IN subquery
+
+ @param thd The context of the statement
+ @param arg Not used
+
+ @details
+ The method transforms this IN predicate into in equivalent IN subquery:
+
+ <left_expr> IN (<value_list>)
+ =>
+ <left_expr> IN (SELECT * FROM (VALUES <transformed_value_list>) AS tvc_#)
+
+ E.g.:
+
+ <value_list> = 5,2,7
+ <transformed_value_list> = (5),(2),(7)
+
+ <value_list> = (5,2),(7,1)
+ <transformed_value_list> = (5,2),(7,1)
+
+ If the transformation succeeds the method returns the result IN subquery,
+ otherwise this IN predicate is returned.
+
+ @retval
+ pointer to the result of transformation if succeeded
+ pointer to this IN predicate otherwise
+*/
+
+Item *Item_func_in::in_predicate_to_in_subs_transformer(THD *thd,
+ uchar *arg)
+{
+ if (!transform_into_subq)
+ return this;
+
+ Json_writer_object trace_wrapper(thd);
+ Json_writer_object trace_conv(thd, "in_to_subquery_conversion");
+ trace_conv.add("item", this);
+
+ transform_into_subq= false;
+
+ List<List_item> values;
+
+ LEX *lex= thd->lex;
+ /* SELECT_LEX object where the transformation is performed */
+ SELECT_LEX *parent_select= lex->current_select;
+ uint8 save_derived_tables= lex->derived_tables;
+
+ /*
+ Make sure that create_tmp_table will not fail due to too long keys.
+ Here the strategy would mainly use materialization, so we need to make
+ sure that the materialized table can be created.
+
+ The checks here are the same as in subquery_type_allows_materialization()
+ */
+ uint32 length= max_length_of_left_expr();
+ if (!length || length > tmp_table_max_key_length() ||
+ args[0]->cols() > tmp_table_max_key_parts())
+ {
+ trace_conv.add("done", false);
+ trace_conv.add("reason", "key is too long");
+ return this;
+ }
+
+ for (uint i=1; i < arg_count; i++)
+ {
+ if (!args[i]->const_item())
+ {
+ trace_conv.add("done", false);
+ trace_conv.add("reason", "non-constant element in the IN-list");
+ return this;
+ }
+
+ if (cmp_row_types(args[i], args[0]))
+ {
+ trace_conv.add("done", false);
+ trace_conv.add("reason", "type mismatch");
+ return this;
+ }
+ }
+ Json_writer_array trace_nested_obj(thd, "conversion");
+
+ Query_arena backup;
+ Query_arena *arena= thd->activate_stmt_arena_if_needed(&backup);
+
+ /*
+ Create SELECT_LEX of the subquery SQ used in the result of transformation
+ */
+ if (mysql_new_select(lex, 1, NULL))
+ goto err;
+ mysql_init_select(lex);
+ /* Create item list as '*' for the subquery SQ */
+ Item *item;
+ SELECT_LEX *sq_select; // select for IN subquery;
+ sq_select= lex->current_select;
+ sq_select->parsing_place= SELECT_LIST;
+ item= new (thd->mem_root) Item_field(thd, &sq_select->context,
+ star_clex_str);
+ if (item == NULL || add_item_to_list(thd, item))
+ goto err;
+ (sq_select->with_wild)++;
+ /*
+ Create derived table DT that will wrap TVC in the result of transformation
+ */
+ SELECT_LEX *tvc_select; // select for tvc
+ SELECT_LEX_UNIT *derived_unit; // unit for tvc_select
+ if (mysql_new_select(lex, 1, NULL))
+ goto err;
+ mysql_init_select(lex);
+ tvc_select= lex->current_select;
+ derived_unit= tvc_select->master_unit();
+ tvc_select->set_linkage(DERIVED_TABLE_TYPE);
+
+ /* Create TVC used in the transformation */
+ if (create_value_list_for_tvc(thd, &values))
+ goto err;
+ if (!(tvc_select->tvc=
+ new (thd->mem_root)
+ table_value_constr(values,
+ tvc_select,
+ tvc_select->options)))
+ goto err;
+
+ lex->current_select= sq_select;
+
+ /*
+ Create the name of the wrapping derived table and
+ add it to the FROM list of the subquery SQ
+ */
+ Table_ident *ti;
+ LEX_CSTRING alias;
+ TABLE_LIST *derived_tab;
+ if (!(ti= new (thd->mem_root) Table_ident(derived_unit)) ||
+ create_tvc_name(thd, parent_select, &alias))
+ goto err;
+ if (!(derived_tab=
+ sq_select->add_table_to_list(thd,
+ ti, &alias, 0,
+ TL_READ, MDL_SHARED_READ)))
+ goto err;
+ sq_select->add_joined_table(derived_tab);
+ sq_select->add_where_field(derived_unit->first_select());
+ sq_select->context.table_list= sq_select->table_list.first;
+ sq_select->context.first_name_resolution_table= sq_select->table_list.first;
+ sq_select->table_list.first->derived_type= DTYPE_TABLE | DTYPE_MATERIALIZE;
+ lex->derived_tables|= DERIVED_SUBQUERY;
+
+ sq_select->where= 0;
+ sq_select->set_braces(false);
+ derived_unit->set_with_clause(0);
+
+ /* Create IN subquery predicate */
+ sq_select->parsing_place= parent_select->parsing_place;
+ Item_in_subselect *in_subs;
+ Item *sq;
+ if (!(in_subs=
+ new (thd->mem_root) Item_in_subselect(thd, args[0], sq_select)))
+ goto err;
+ in_subs->converted_from_in_predicate= TRUE;
+ sq= in_subs;
+ if (negated)
+ sq= negate_expression(thd, in_subs);
+ else
+ in_subs->emb_on_expr_nest= emb_on_expr_nest;
+
+ if (arena)
+ thd->restore_active_arena(arena, &backup);
+ thd->lex->current_select= parent_select;
+
+ if (sq->fix_fields(thd, (Item **)&sq))
+ goto err;
+
+ parent_select->curr_tvc_name++;
+
+ return sq;
+
+err:
+ if (arena)
+ thd->restore_active_arena(arena, &backup);
+ lex->derived_tables= save_derived_tables;
+ thd->lex->current_select= parent_select;
+ return NULL;
+}
+
+
+uint32 Item_func_in::max_length_of_left_expr()
+{
+ uint n= args[0]->cols();
+ uint32 length= 0;
+ for (uint i=0; i < n; i++)
+ length+= args[0]->element_index(i)->max_length;
+ return length;
+}
+
+
+/**
+ @brief
+ Check if this IN-predicate can be transformed in IN-subquery
+ with TVC
+
+ @param thd The context of the statement
+
+ @details
+ Compare the number of elements in the list of
+ values in this IN-predicate with the
+ in_subquery_conversion_threshold special variable
+
+ @retval
+ true if transformation can be made
+ false otherwise
+*/
+
+bool Item_func_in::to_be_transformed_into_in_subq(THD *thd)
+{
+ uint values_count= arg_count-1;
+
+ if (args[1]->type() == Item::ROW_ITEM)
+ values_count*= ((Item_row *)(args[1]))->cols();
+
+ if (thd->variables.in_subquery_conversion_threshold == 0 ||
+ thd->variables.in_subquery_conversion_threshold > values_count)
+ return false;
+
+ return true;
+}
+
+
+/**
+ @brief
+ Transform IN predicates into IN subqueries in WHERE and ON expressions
+
+ @param thd The context of the statement
+
+ @details
+ For each IN predicate from AND parts of the WHERE condition and/or
+ ON expressions of the SELECT for this join the method performs
+ the intransformation into an equivalent IN sunquery if it's needed.
+
+ @retval
+ false always
+*/
+
+bool JOIN::transform_in_predicates_into_in_subq(THD *thd)
+{
+ DBUG_ENTER("JOIN::transform_in_predicates_into_in_subq");
+ if (!select_lex->in_funcs.elements)
+ DBUG_RETURN(false);
+
+ SELECT_LEX *save_current_select= thd->lex->current_select;
+ enum_parsing_place save_parsing_place= select_lex->parsing_place;
+ thd->lex->current_select= select_lex;
+ if (conds)
+ {
+ select_lex->parsing_place= IN_WHERE;
+ conds=
+ conds->transform(thd,
+ &Item::in_predicate_to_in_subs_transformer,
+ (uchar*) 0);
+ if (!conds)
+ DBUG_RETURN(true);
+ select_lex->prep_where= conds ? conds->copy_andor_structure(thd) : 0;
+ select_lex->where= conds;
+ }
+
+ if (join_list)
+ {
+ TABLE_LIST *table;
+ List_iterator<TABLE_LIST> li(*join_list);
+ select_lex->parsing_place= IN_ON;
+
+ while ((table= li++))
+ {
+ if (table->on_expr)
+ {
+ table->on_expr=
+ table->on_expr->transform(thd,
+ &Item::in_predicate_to_in_subs_transformer,
+ (uchar*) 0);
+ if (!table->on_expr)
+ DBUG_RETURN(true);
+ table->prep_on_expr= table->on_expr ?
+ table->on_expr->copy_andor_structure(thd) : 0;
+ }
+ }
+ }
+
+ select_lex->in_funcs.empty();
+ select_lex->parsing_place= save_parsing_place;
+ thd->lex->current_select= save_current_select;
+ DBUG_RETURN(false);
+}
+