#include <item_subselect.h>

Inheritance diagram for subselect_hash_sj_engine:

Collaboration diagram for subselect_hash_sj_engine:

Public Member Functions
	subselect_hash_sj_engine (THD thd, Item_subselect in_predicate, subselect_single_select_engine *old_engine)
bool	setup (List< Item > *tmp_columns)
virtual void	cleanup ()
virtual bool	prepare ()
virtual bool	exec ()
virtual void	print (String *str, enum_query_type query_type)
virtual uint	cols () const
virtual enum_engine_type	engine_type () const
const st_join_table *	get_join_tab () const
Item *	get_cond_for_explain () const
Public Member Functions inherited from subselect_indexsubquery_engine
	subselect_indexsubquery_engine (THD thd_arg, st_join_table tab_arg, Item_subselect subs, Item where, Item *having_arg, bool chk_null, bool unique_arg)
virtual void	fix_length_and_dec (Item_cache **row)
virtual uint8	uncacheable () const
virtual void	exclude ()
virtual table_map	upper_select_const_tables () const
virtual bool	change_result (Item_subselect si, select_result_interceptor result)
virtual bool	no_tables () const
bool	scan_table ()
void	copy_ref_key (bool require_scan, bool convert_error)
Public Member Functions inherited from subselect_engine
	subselect_engine (Item_subselect si, select_result_interceptor res)
void	set_thd_for_result ()
	Sets "thd" for 'result'. Should be called before prepare()
virtual enum Item_result	type () const
virtual enum_field_types	field_type () const
virtual bool	may_be_null () const
virtual bool	is_executed () const
const Item_subselect *	get_item () const

Additional Inherited Members
Public Types inherited from subselect_engine
enum	enum_engine_type { ABSTRACT_ENGINE, SINGLE_SELECT_ENGINE, UNION_ENGINE, UNIQUESUBQUERY_ENGINE, INDEXSUBQUERY_ENGINE, HASH_SJ_ENGINE }
Static Public Member Functions inherited from subselect_engine
static table_map	calc_const_tables (TABLE_LIST *)
Protected Member Functions inherited from subselect_engine
void	set_row (List< Item > &item_list, Item_cache **row)
Protected Attributes inherited from subselect_indexsubquery_engine
st_join_table *	tab
Item *	cond

Detailed Description

Compute an IN predicate via a hash semi-join. The subquery is materialized during the first evaluation of the IN predicate. The IN predicate is executed via the functionality inherited from subselect_indexsubquery_engine.

Definition at line 744 of file item_subselect.h.

Member Function Documentation

void subselect_hash_sj_engine::cleanup ( )

virtual

Cleanup performed after each PS execution.

Called in the end of JOIN::prepare for PS from Item_subselect::cleanup.

Reimplemented from subselect_indexsubquery_engine.

Definition at line 3700 of file item_subselect.cc.

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bool subselect_hash_sj_engine::exec ( )

virtual

Execute a subquery IN predicate via materialization.

If needed materialize the subquery into a temporary table, then copmpute the predicate via a lookup into this table.

Return values

TRUE	if error
FALSE	otherwise

Reimplemented from subselect_indexsubquery_engine.

Definition at line 3727 of file item_subselect.cc.

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void subselect_hash_sj_engine::print	(	String *	str,
		enum_query_type	query_type
	)

virtual

Print the state of this engine into a string for debugging and views.

Reimplemented from subselect_indexsubquery_engine.

Definition at line 3847 of file item_subselect.cc.

bool subselect_hash_sj_engine::setup ( List< Item > * tmp_columns )

Create all structures needed for subquery execution using hash semijoin.

Create a temporary table to store the result of the IN subquery. The temporary table has one hash index on all its columns. If single-column, the index allows at most one NULL row.
Create a new result sink that sends the result stream of the subquery to the temporary table,
Create and initialize a new JOIN_TAB, and TABLE_REF objects to perform lookups into the indexed temporary table.

Parameters

tmp_columns columns of temporary table

: Currently Item_subselect::init() already chooses and creates at parse time an engine with a corresponding JOIN to execute the subquery.

Return values

TRUE	if error
FALSE	otherwise

Definition at line 3492 of file item_subselect.cc.

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The documentation for this class was generated from the following files:

sql/item_subselect.h
sql/item_subselect.cc

Public Member Functions

Additional Inherited Members

Detailed Description

Member Function Documentation