drizzled::subselect_single_select_engine Class Reference

Inheritance diagram for drizzled::subselect_single_select_engine:

List of all members.

Public Types
enum	enum_engine_type {   ABSTRACT_ENGINE, SINGLE_SELECT_ENGINE, UNION_ENGINE, UNIQUESUBQUERY_ENGINE,   INDEXSUBQUERY_ENGINE, HASH_SJ_ENGINE }
Public Member Functions
	subselect_single_select_engine (Select_Lex *select, select_result_interceptor *result, Item_subselect *item)
void	cleanup ()
int	prepare ()
void	fix_length_and_dec (Item_cache **row)
int	exec ()
uint32_t	cols ()
bool	uncacheable ()
bool	uncacheable (uint32_t bit_pos)
void	exclude ()
table_map	upper_select_const_tables ()
virtual void	print (String *str)
bool	change_result (Item_subselect *si, select_result_interceptor *result)
bool	no_tables ()
bool	may_be_null ()
bool	is_executed () const
bool	no_rows ()
virtual enum_engine_type	engine_type ()
bool	save_join_if_explain ()
void	set_session (Session *session_arg)
Session *	get_session ()
enum Item_result	type ()
enum_field_types	field_type ()
Static Public Member Functions
static table_map	calc_const_tables (TableList *)
static void *	operator new (size_t size)
static void *	operator new (size_t size, Root *mem_root)
static void *	operator new[] (size_t size)
static void *	operator new[] (size_t size, Root *mem_root)
static void	operator delete (void *, size_t)
static void	operator delete (void *, Root *)
static void	operator delete[] (void *, Root *)
static void	operator delete[] (void *, size_t)
Protected Member Functions
void	set_row (List< Item > &item_list, Item_cache **row)
Protected Attributes
select_result_interceptor *	result
Session *	session
Item_subselect *	item
enum Item_result	res_type
enum_field_types	res_field_type
bool	maybe_null
Private Attributes
bool	prepared
bool	optimized
bool	executed
Select_Lex *	select_lex
Join *	join
Friends
class	subselect_hash_sj_engine
class	Item_in_subselect

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Detailed Description

Definition at line 486 of file subselect.h.

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Member Function Documentation

bool drizzled::subselect_single_select_engine::change_result	(	Item_subselect *	si,
		select_result_interceptor *	res
	)		[virtual]

change select_result object of engine.

Parameters:

si	new subselect Item
res	new select_result object

Return values:

false	OK
true	error

Implements drizzled::subselect_engine.

Definition at line 2870 of file subselect.cc.

bool drizzled::subselect_single_select_engine::no_tables

(

)

[virtual]

Report about presence of tables in subquery.

Return values:

true	there are not tables used in subquery
false	there are some tables in subquery

Implements drizzled::subselect_engine.

Definition at line 2929 of file subselect.cc.

int drizzled::subselect_single_select_engine::prepare

(

)

[virtual]

Create and prepare the JOIN object that represents the query execution plan for the subquery.

This method is called from Item_subselect::fix_fields. For prepared statements it is called both during the PREPARE and EXECUTE phases in the following ways:

• During PREPARE the optimizer needs some properties (join->fields_list.elements) of the JOIN to proceed with preparation of the remaining query (namely to complete ::fix_fields for the subselect related classes. In the end of PREPARE the JOIN is deleted.
• When we EXECUTE the query, Item_subselect::fix_fields is called again, and the JOIN object is re-created again, prepared and executed. In the end of execution it is deleted. In all cases the JOIN is created in runtime memory (not in the permanent memory root).

Todo:

Re-check what properties of 'join' are needed during prepare, and see if we can avoid creating a JOIN during JOIN::prepare of the outer join.

Return values:

0	if success
1	if error

Implements drizzled::subselect_engine.

Definition at line 2037 of file subselect.cc.

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

• drizzled/item/subselect.h
• drizzled/item/subselect.cc