finalize_plan.cc File Reference

#include "sql/join_optimizer/finalize_plan.h"
#include <assert.h>
#include <algorithm>
#include <functional>
#include "mem_root_deque.h"
#include "my_alloc.h"
#include "my_base.h"
#include "my_inttypes.h"
#include "my_sqlcommand.h"
#include "my_table_map.h"
#include "prealloced_array.h"
#include "sql/filesort.h"
#include "sql/item.h"
#include "sql/item_cmpfunc.h"
#include "sql/item_sum.h"
#include "sql/join_optimizer/access_path.h"
#include "sql/join_optimizer/bit_utils.h"
#include "sql/join_optimizer/join_optimizer.h"
#include "sql/join_optimizer/materialize_path_parameters.h"
#include "sql/join_optimizer/relational_expression.h"
#include "sql/join_optimizer/replace_item.h"
#include "sql/join_optimizer/walk_access_paths.h"
#include "sql/mem_root_array.h"
#include "sql/sql_class.h"
#include "sql/sql_const.h"
#include "sql/sql_executor.h"
#include "sql/sql_insert.h"
#include "sql/sql_lex.h"
#include "sql/sql_list.h"
#include "sql/sql_optimizer.h"
#include "sql/sql_resolver.h"
#include "sql/sql_select.h"
#include "sql/sql_tmp_table.h"
#include "sql/table.h"
#include "sql/temp_table_param.h"
#include "sql/visible_fields.h"
#include "sql/window.h"
#include "template_utils.h"

Namespaces
namespace	anonymous_namespace{finalize_plan.cc}

Functions
static bool	IsMaterializePathForDeduplication (AccessPath *path)
static bool	IsMaterializePathForDistinct (AccessPath *path)
static bool	IsMaterializePathForGroupBy (AccessPath *path)
static bool	HasVisibleBitItems (bool is_distinct, mem_root_deque< Item * > *distinct_items, bool is_group_by, ORDER *group)
	Search for visible BIT items, and return true if found. More...
static void	ReplaceUpdateValuesWithTempTableFields (Sql_cmd_insert_select *sql_cmd, Query_block *query_block, const mem_root_deque< Item * > &original_fields, const mem_root_deque< Item * > &temp_table_fields)
	Replaces field references in an ON DUPLICATE KEY UPDATE clause with references to corresponding fields in a temporary table. More...
static void	CollectItemsWithoutRollup (Item *root, mem_root_deque< Item * > *items)
	Collects the set of items in the item tree that satisfy the following: More...
static TABLE *	CreateTemporaryTableFromSelectList (THD *thd, Query_block *query_block, Window *window, Temp_table_param **temp_table_param_arg, bool after_aggregation, bool is_group_by=false, bool is_distinct=false)
	Creates a temporary table with columns matching the SELECT list of the given query block. More...
static void	ReplaceSelectListWithTempTableFields (THD *thd, JOIN *join, const Func_ptr_array &items_to_copy, Mem_root_array< const Func_ptr_array * > *applied_replacements)
	Replaces the items in the SELECT list with items that point to fields in a temporary table. More...
static bool	InitTmpTableSliceRefs (THD *thd, AccessPath *path, JOIN *join)
	In hypergraph optimizer, slices are currently used only for temp tables created for GROUP BY; i.e. More...
void	ReplaceOrderItemsWithTempTableFields (THD *thd, ORDER *order, const Func_ptr_array &items_to_copy)
table_map	anonymous_namespace{finalize_plan.cc}::GetUsedTableMap (const ORDER *order)
bool	anonymous_namespace{finalize_plan.cc}::OrderItemsReferenceUnavailableTables (const AccessPath *sort_path, table_map used_tables_before_replacement)
	Checks if the order items in a SORT access path reference any column that is not available to it. More...
static Temp_table_param *	GetItemsToCopy (AccessPath *path)
static bool	UpdateReferencesToMaterializedItems (THD *thd, Query_block *query_block, AccessPath *path, bool after_aggregation, Mem_root_array< const Func_ptr_array * > *applied_replacements)
	See FinalizePlanForQueryBlock(). More...
static bool	DelayedCreateTemporaryTable (THD *thd, Query_block *query_block, AccessPath *path, bool after_aggregation, TABLE **last_window_temp_table, unsigned *num_windows_seen)
	If the given access path needs a temporary table, it instantiates said table (we cannot do this until we have a final access path list, where we know which temporary tables are created and in which order). More...
static void	FinalizeWindowPath (THD *thd, Query_block *query_block, const mem_root_deque< Item * > &original_fields, const Mem_root_array< const Func_ptr_array * > &applied_replacements, AccessPath *path)
	See FinalizePlanForQueryBlock(). More...
static Item *	AddCachesAroundConstantConditions (Item *item)
static bool	AddCachesAroundConstantConditionsInPath (AccessPath *path)
bool	FinalizePlanForQueryBlock (THD *thd, Query_block *query_block)

Function Documentation

AddCachesAroundConstantConditions()

static Item * AddCachesAroundConstantConditions ( Item *  item )

static

AddCachesAroundConstantConditionsInPath()

static bool AddCachesAroundConstantConditionsInPath ( AccessPath *  path )

static

CollectItemsWithoutRollup()

static void CollectItemsWithoutRollup ( Item *  root, mem_root_deque< Item * > *  items  )

static

Collects the set of items in the item tree that satisfy the following:

1) Neither the item itself nor any of its descendants have a reference to a ROLLUP expression (item->has_grouping_set_dep() evaluates to false). 2) The item is either the root item or its parent item does not satisfy 1).

In other words, we do not collect every item without rollup in the tree. Instead we collect the root item of every largest possible subtree where none of the items in the subtree have rollup.

Parameters

root	The root item of the tree to search.
items	A collection of items. We add items that satisfy the search criteria to this collection.

CreateTemporaryTableFromSelectList()

static TABLE * CreateTemporaryTableFromSelectList ( THD *  thd, Query_block *  query_block, Window *  window, Temp_table_param **  temp_table_param_arg, bool  after_aggregation, bool  is_group_by = false, bool  is_distinct = false  )

static

Creates a temporary table with columns matching the SELECT list of the given query block.

(In FinalizePlanForQueryBlock(), the SELECT list of the query block is updated to point to the fields in the temporary table, but not here.)

This function is used for materializing the query result, either as an intermediate step before sorting the final result if the sort requires the rows to come from a single table instead of a join, or as the last step if the SQL_BUFFER_RESULT query option has been specified. It is also used for setting up the output temporary table for window functions.

NOTE: If after_aggregation = true, it is impossible to call this function again later with after_aggregation = false, as count_field_types() will remove item->has_aggregation() once called. Thus, we need to set up all these temporary tables in FinalizePlanForQueryBlock(), in the right order. 'is_group_by'=true indicates that the temp table is to be created with rows grouped using GROUP BY items. 'is_distinct'=true indicates that the temp table is to be created with distinct rows. (corresponds to SELECT DISTINCT ...)

DelayedCreateTemporaryTable()

static bool DelayedCreateTemporaryTable ( THD *  thd, Query_block *  query_block, AccessPath *  path, bool  after_aggregation, TABLE **  last_window_temp_table, unsigned *  num_windows_seen  )

static

If the given access path needs a temporary table, it instantiates said table (we cannot do this until we have a final access path list, where we know which temporary tables are created and in which order).

For window functions, it also needs to forward this information to the materialization access path coming right after this window, if any, so it uses last_window_temp_table as a buffer to hold this.

FinalizePlanForQueryBlock()

bool FinalizePlanForQueryBlock	(	THD *	thd,
		Query_block *	query_block
	)

FinalizeWindowPath()

static void FinalizeWindowPath ( THD *  thd, Query_block *  query_block, const mem_root_deque< Item * > &  original_fields, const Mem_root_array< const Func_ptr_array * > &  applied_replacements, AccessPath *  path  )

static

See FinalizePlanForQueryBlock().

GetItemsToCopy()

static Temp_table_param * GetItemsToCopy ( AccessPath *  path )

static

HasVisibleBitItems()

static bool HasVisibleBitItems ( bool  is_distinct, mem_root_deque< Item * > *  distinct_items, bool  is_group_by, ORDER *  group  )

static

Search for visible BIT items, and return true if found.

Used specifically for avoiding bit-to-long type conversion of visible join fields.

InitTmpTableSliceRefs()

static bool InitTmpTableSliceRefs ( THD *  thd, AccessPath *  path, JOIN *  join  )

static

In hypergraph optimizer, slices are currently used only for temp tables created for GROUP BY; i.e.

temp table aggregation and materialization with deduplication (not for DISTINCT deduplication or UNION deduplication).

For GROUP BY, we require slices to handle subqueries in HAVING clause.

For DISTINCT, we don't require slices. ORDER BY clause is the only clause that is appled after DISTINCT. And the ORDER BY expression is always added as a hidden select item, and the temp table always has this item as one of its columns. This means that the expression is already evaluated and materialized in the temp table; there is no further evaluation. If it were not materialized, any Item refs (e.g. if the expression is a subquery) would have required a temp table slice for evaluation, but because it is already materialized, we don't require slices.

(Note: The temp-table item replacement infrastructure doesn't support items inside subqueries, hence slices).

IsMaterializePathForDeduplication()

static bool IsMaterializePathForDeduplication ( AccessPath *  path )

static

IsMaterializePathForDistinct()

static bool IsMaterializePathForDistinct ( AccessPath *  path )

static

IsMaterializePathForGroupBy()

static bool IsMaterializePathForGroupBy ( AccessPath *  path )

static

ReplaceOrderItemsWithTempTableFields()

void ReplaceOrderItemsWithTempTableFields	(	THD *	thd,
		ORDER *	order,
		const Func_ptr_array &	items_to_copy
	)

ReplaceSelectListWithTempTableFields()

static void ReplaceSelectListWithTempTableFields ( THD *  thd, JOIN *  join, const Func_ptr_array &  items_to_copy, Mem_root_array< const Func_ptr_array * > *  applied_replacements  )

static

Replaces the items in the SELECT list with items that point to fields in a temporary table.

See FinalizePlanForQueryBlock() for more information. Also creates a new items_to_copy list made up of aggregate items that were not found while finding replacement. These items need to be added in 'applied_replacements' so that further items get a direct match for subsequent occurences of these items, rather than generating a new replacement. Without this, the replacement does not propagate from the bottom to the top plan node.

ReplaceUpdateValuesWithTempTableFields()

static void ReplaceUpdateValuesWithTempTableFields ( Sql_cmd_insert_select *  sql_cmd, Query_block *  query_block, const mem_root_deque< Item * > &  original_fields, const mem_root_deque< Item * > &  temp_table_fields  )

static

Replaces field references in an ON DUPLICATE KEY UPDATE clause with references to corresponding fields in a temporary table.

The changes will be rolled back at the end of execution and will have to be redone during optimization in the next execution.

UpdateReferencesToMaterializedItems()

static bool UpdateReferencesToMaterializedItems ( THD *  thd, Query_block *  query_block, AccessPath *  path, bool  after_aggregation, Mem_root_array< const Func_ptr_array * > *  applied_replacements  )

static

See FinalizePlanForQueryBlock().