Inheritance diagram for Item_subselect:

Public Types
enum	trans_res { RES_OK, RES_REDUCE, RES_ERROR }
enum	subs_type { UNKNOWN_SUBS, SINGLEROW_SUBS, EXISTS_SUBS, IN_SUBS, ALL_SUBS, ANY_SUBS }
Public Member Functions
const subselect_engine *	get_engine_for_explain () const
	EXPLAIN needs read-only access to the engine.
virtual subs_type	substype ()
virtual void	init (st_select_lex select_lex, select_result_interceptor result)
virtual void	cleanup ()
virtual void	reset ()
virtual trans_res	select_transformer (JOIN *join)
bool	assigned () const
void	assigned (bool a)
enum Type	type () const
bool	is_null ()
bool	fix_fields (THD thd, Item *ref)
void	fix_after_pullout (st_select_lex parent_select, st_select_lex removed_select)
virtual bool	exec ()
virtual void	fix_length_and_dec ()
table_map	used_tables () const
table_map	not_null_tables () const
bool	const_item () const
table_map	get_used_tables_cache ()
bool	get_const_item_cache ()
Item *	get_tmp_table_item (THD *thd)
void	update_used_tables ()
virtual void	print (String *str, enum_query_type query_type)
virtual bool	have_guarded_conds ()
bool	change_engine (subselect_engine *eng)
bool	is_evaluated () const
bool	is_uncacheable () const
virtual void	reset_value_registration ()
enum_parsing_place	place ()
bool	walk_join_condition (List< TABLE_LIST > tables, Item_processor processor, bool walk_subquery, uchar argument)
bool	walk_body (Item_processor processor, bool walk_subquery, uchar *arg)
bool	walk (Item_processor processor, bool walk_subquery, uchar *arg)
virtual bool	explain_subquery_checker (uchar **arg)
bool	inform_item_in_cond_of_tab (uchar *join_tab_index)
virtual bool	clean_up_after_removal (uchar *arg)
const char *	func_name () const
Public Attributes
Item *	substitution
st_select_lex_unit *	unit
int	in_cond_of_tab
bool	engine_changed
bool	changed
Protected Attributes
subselect_engine *	engine
subselect_engine *	old_engine
table_map	used_tables_cache
uint	max_columns
enum_parsing_place	parsing_place
bool	have_to_be_excluded
bool	const_item_cache
Friends
class	select_result_interceptor
class	Item_in_optimizer
bool	Item_field::fix_fields (THD , Item *)
int	Item_field::fix_outer_field (THD , Field , Item *)
bool	Item_ref::fix_fields (THD , Item *)
void	Item_ident::fix_after_pullout (st_select_lex parent_select, st_select_lex removed_selec)
void	mark_select_range_as_dependent (THD , st_select_lex , st_select_lex , Field , Item , Item_ident )

Member Function Documentation

bool Item_subselect::clean_up_after_removal ( uchar * arg ) [virtual]

Clean up after removing the subquery from the item tree.

Call st_select_lex_unit::exclude_tree() to unlink it from its master and to unlink direct st_select_lex children from all_selects_list.

Don't unlink subqueries that are not descendants of the starting point (root) of the removal and cleanup.

Reimplemented from Item.

bool Item_subselect::explain_subquery_checker ( uchar ** arg ) [virtual]

Mark a subquery unit with information provided

A subquery may belong to WHERE, HAVING, ORDER BY or GROUP BY item trees. This "processor" qualifies subqueries by outer clause type.

Note:: For the WHERE clause of the JOIN query this function also associates a related table with the unit.

Parameters:

arg	Explain_subquery_marker structure

Return values:

false

Note:: We always return "false" as far as we don't want to dive deeper because we explain inner subqueries in their joins contexts.

Reimplemented from Item.

void Item_subselect::fix_after_pullout	(	st_select_lex *	parent_select,
		st_select_lex *	removed_select
	)		`[virtual]`

Fix used tables information for a subquery after query transformations. Common actions for all predicates involving subqueries. Most actions here involve re-resolving information for conditions and items belonging to the subquery. Notice that the usage information from underlying expressions is not propagated to the subquery predicate, as it belongs to inner layers of the query operator structure. However, when underlying expressions contain outer references into a select_lex on this level, the relevant information must be updated when these expressions are resolved.

Reimplemented from Item.

Reimplemented in Item_in_subselect.

bool Item_subselect::inform_item_in_cond_of_tab ( uchar * join_tab_index ) [virtual]

Tells an Item that it is in the condition of a JOIN_TAB

Parameters:

'join_tab_index' index of JOIN_TAB in JOIN's array

The Item records this fact and can deduce from it the estimated number of times that it will be evaluated.

Reimplemented from Item.

void Item_subselect::print	(	String *	str,
		enum_query_type	query_type
	)		`[virtual]`

This method is used for to:

to generate a view definition query (SELECT-statement);
to generate a SQL-query for EXPLAIN EXTENDED;
to generate a SQL-query to be shown in INFORMATION_SCHEMA;
debug.

For more information about view definition query, INFORMATION_SCHEMA query and why they should be generated from the Item-tree,

See also:: mysql_register_view().

Reimplemented from Item.

Reimplemented in Item_allany_subselect, Item_in_subselect, Item_exists_subselect, and Item_maxmin_subselect.

bool Item_subselect::walk_body	(	Item_processor	processor,
		bool	walk_subquery,
		uchar *	argument
	)

Workaround for bug in gcc 4.1. Item_in_subselect::walk()

bool Item_subselect::walk_join_condition	(	List< TABLE_LIST > *	tables,
		Item_processor	processor,
		bool	walk_subquery,
		uchar *	argument
	)

Apply walk() processor to join conditions.

JOINs may be nested. Walk nested joins recursively to apply the processor.

Member Data Documentation

int Item_subselect::in_cond_of_tab

If !=INT_MIN: this Item is in the condition attached to the JOIN_TAB having this index in the parent JOIN.

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

Public Types

Public Member Functions

Public Attributes

Protected Attributes

Friends

Member Function Documentation

Member Data Documentation