#include <item_subselect.h>

Inheritance diagram for Item_in_subselect:

Collaboration diagram for Item_in_subselect:

Classes
struct	In2exists_info

Public Member Functions
bool	in2exists_added_to_where () const
bool	originally_dependent () const
	Is reliable only if IN->EXISTS has been done.
bool *	get_cond_guard (int i)
void	set_cond_guard_var (int i, bool v)
bool	have_guarded_conds ()
	Item_in_subselect (Item left_expr, st_select_lex select_lex)
virtual void	cleanup ()
subs_type	substype ()
virtual void	reset ()
trans_res	select_transformer (JOIN *join)
trans_res	select_in_like_transformer (JOIN join, Comp_creator func)
trans_res	single_value_transformer (JOIN join, Comp_creator func)
trans_res	row_value_transformer (JOIN *join)
trans_res	single_value_in_to_exists_transformer (JOIN join, Comp_creator func)
trans_res	row_value_in_to_exists_transformer (JOIN *join)
bool	walk (Item_processor processor, bool walk_subquery, uchar *arg)
virtual bool	exec ()
longlong	val_int ()
double	val_real ()
String *	val_str (String *)
my_decimal *	val_decimal (my_decimal *)
void	update_null_value ()
bool	val_bool ()
void	top_level_item ()
bool	is_top_level_item ()
bool	test_limit (st_select_lex_unit *unit)
virtual void	print (String *str, enum_query_type query_type)
bool	fix_fields (THD thd, Item *ref)
void	fix_after_pullout (st_select_lex parent_select, st_select_lex removed_select)
bool	init_left_expr_cache ()
bool	finalize_exists_transform (SELECT_LEX *select_lex)
bool	finalize_materialization_transform (JOIN *join)
Public Member Functions inherited from Item_exists_subselect
	Item_exists_subselect (st_select_lex *select_lex)
enum Item_result	result_type () const
bool	get_date (MYSQL_TIME *ltime, uint fuzzydate)
bool	get_time (MYSQL_TIME *ltime)
void	fix_length_and_dec ()
Public Member Functions inherited from Item_subselect
const subselect_engine *	get_engine_for_explain () const
	EXPLAIN needs read-only access to the engine.
virtual void	init (st_select_lex select_lex, select_result_interceptor result)
bool	assigned () const
void	assigned (bool a)
enum Type	type () const
bool	is_null ()
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 ()
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)
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 Member Functions inherited from Item_result_field
	Item_result_field (THD thd, Item_result_field item)
Field *	get_tmp_table_field ()
Field *	tmp_table_field (TABLE *t_arg)
void	set_result_field (Field *field)
bool	is_result_field ()
void	save_in_result_field (bool no_conversions)
Public Member Functions inherited from Item
	Item (THD thd, Item item)
void	rename (char *new_name)
void	init_make_field (Send_field *tmp_field, enum enum_field_types type)
virtual void	make_field (Send_field *field)
virtual Field *	make_string_field (TABLE *table)
void	quick_fix_field ()
type_conversion_status	save_in_field_no_warnings (Field *field, bool no_conversions)
virtual type_conversion_status	save_in_field (Field *field, bool no_conversions)
virtual void	save_org_in_field (Field *field)
virtual type_conversion_status	save_safe_in_field (Field *field)
virtual bool	send (Protocol protocol, String str)
virtual bool	eq (const Item *, bool binary_cmp) const
virtual enum Item_result	numeric_context_result_type () const
enum Item_result	temporal_with_date_as_number_result_type () const
virtual Item_result	cast_to_int_type () const
virtual enum_field_types	string_field_type () const
virtual enum_field_types	field_type () const
virtual enum_monotonicity_info	get_monotonicity_info () const
virtual longlong	val_int_endpoint (bool left_endp, bool *incl_endp)
virtual longlong	val_date_temporal ()
virtual longlong	val_time_temporal ()
longlong	val_temporal_by_field_type ()
longlong	val_temporal_with_round (enum_field_types type, uint8 dec)
ulonglong	val_uint ()
virtual String *	val_str_ascii (String *str)
virtual String *	val_nodeset (String *)
type_conversion_status	save_time_in_field (Field *field)
type_conversion_status	save_date_in_field (Field *field)
type_conversion_status	save_str_value_in_field (Field field, String result)
virtual const char *	full_name () const
virtual double	val_result ()
virtual longlong	val_int_result ()
virtual longlong	val_time_temporal_result ()
virtual longlong	val_date_temporal_result ()
virtual String *	str_result (String *tmp)
virtual my_decimal *	val_decimal_result (my_decimal *val)
virtual bool	val_bool_result ()
virtual bool	is_null_result ()
virtual table_map	resolved_used_tables () const
virtual bool	basic_const_item () const
virtual Item *	clone_item ()
virtual cond_result	eq_cmp_result () const
uint	float_length (uint decimals_par) const
virtual uint	decimal_precision () const
int	decimal_int_part () const
virtual uint	time_precision ()
virtual uint	datetime_precision ()
virtual bool	const_during_execution () const
void	print_item_w_name (String *, enum_query_type query_type)
void	print_for_order (String *str, enum_query_type query_type, bool used_alias)
virtual void	split_sum_func (THD *thd, Ref_ptr_array ref_pointer_array, List< Item > &fields)
void	split_sum_func2 (THD thd, Ref_ptr_array ref_pointer_array, List< Item > &fields, Item *ref, bool skip_registered)
virtual bool	get_timeval (struct timeval tm, int warnings)
virtual bool	get_date_result (MYSQL_TIME *ltime, uint fuzzydate)
virtual bool	is_bool_func ()
virtual void	no_rows_in_result ()
virtual Item *	copy_or_same (THD *thd)
virtual Item *	copy_andor_structure (THD *thd, bool real_items=false)
virtual Item *	real_item ()
virtual const CHARSET_INFO *	compare_collation ()
virtual const CHARSET_INFO *	charset_for_protocol (void) const
virtual Item *	transform (Item_transformer transformer, uchar *arg)
virtual Item *	compile (Item_analyzer analyzer, uchar *arg_p, Item_transformer transformer, uchar arg_t)
virtual void	traverse_cond (Cond_traverser traverser, void *arg, traverse_order order)
virtual bool	intro_version (uchar *int_arg)
virtual bool	remove_dependence_processor (uchar *arg)
virtual bool	remove_fixed (uchar *arg)
virtual bool	cleanup_processor (uchar *arg)
virtual bool	collect_item_field_processor (uchar *arg)
virtual bool	add_field_to_set_processor (uchar *arg)
virtual bool	remove_column_from_bitmap (uchar *arg)
virtual bool	find_item_in_field_list_processor (uchar *arg)
virtual bool	change_context_processor (uchar *context)
virtual bool	reset_query_id_processor (uchar *query_id_arg)
virtual bool	find_item_processor (uchar *arg)
virtual bool	register_field_in_read_map (uchar *arg)
virtual bool	cache_const_expr_analyzer (uchar **arg)
virtual Item *	cache_const_expr_transformer (uchar *arg)
virtual bool	item_field_by_name_analyzer (uchar **arg)
virtual Item *	item_field_by_name_transformer (uchar *arg)
virtual bool	equality_substitution_analyzer (uchar **arg)
virtual Item *	equality_substitution_transformer (uchar *arg)
virtual bool	check_partition_func_processor (uchar *bool_arg)
virtual bool	subst_argument_checker (uchar **arg)
virtual Item *	explain_subquery_propagator (uchar *arg)
virtual Item *	equal_fields_propagator (uchar *arg)
virtual bool	set_no_const_sub (uchar *arg)
virtual Item *	replace_equal_field (uchar *arg)
virtual bool	check_valid_arguments_processor (uchar *bool_arg)
virtual bool	find_function_processor (uchar *arg)
virtual Item *	this_item ()
virtual const Item *	this_item () const
virtual Item **	this_item_addr (THD thd, Item *addr_arg)
virtual uint	cols ()
virtual Item *	element_index (uint i)
virtual Item **	addr (uint i)
virtual bool	check_cols (uint c)
virtual bool	null_inside ()
virtual void	bring_value ()
Field *	tmp_table_field_from_field_type (TABLE *table, bool fixed_length)
virtual Item_field *	field_for_view_update ()
virtual Item *	neg_transformer (THD *thd)
virtual Item *	update_value_transformer (uchar *select_arg)
virtual Item *	safe_charset_converter (const CHARSET_INFO *tocs)
void	delete_self ()
virtual bool	is_splocal ()
virtual Settable_routine_parameter *	get_settable_routine_parameter ()
bool	is_temporal_with_date () const
bool	is_temporal_with_date_and_time () const
bool	is_temporal_with_time () const
bool	is_temporal () const
bool	has_compatible_context (Item *item) const
virtual Field::geometry_type	get_geometry_type () const
String *	check_well_formed_result (String *str, bool send_error=0)
bool	eq_by_collation (Item item, bool binary_cmp, const CHARSET_INFO cs)
virtual bool	is_expensive ()
virtual bool	can_be_evaluated_now () const
uint32	max_char_length () const
void	fix_length_and_charset (uint32 max_char_length_arg, const CHARSET_INFO *cs)
void	fix_char_length (uint32 max_char_length_arg)
void	fix_char_length_ulonglong (ulonglong max_char_length_arg)
void	fix_length_and_charset_datetime (uint32 max_char_length_arg)
void	fix_length_and_dec_and_charset_datetime (uint32 max_char_length_arg, uint8 dec_arg)
virtual bool	is_outer_field () const
bool	is_blob_field () const
virtual bool	has_subquery () const
virtual bool	has_stored_program () const
virtual bool	created_by_in2exists () const
	Whether this Item was created by the IN->EXISTS subquery transformation.

Public Attributes
Item *	left_expr
bool *	pushed_cond_guards
Item_func_not_all *	upper_item
TABLE_LIST *	expr_join_nest
Public Attributes inherited from Item_exists_subselect
enum_exec_method	exec_method
int	sj_convert_priority
	Priority of this predicate in the convert-to-semi-join-nest process.
bool	sj_chosen
	True if this predicate is chosen for semi-join transformation.
TABLE_LIST *	embedding_join_nest
Public Attributes inherited from Item_subselect
Item *	substitution
st_select_lex_unit *	unit
int	in_cond_of_tab
bool	engine_changed
bool	changed
Public Attributes inherited from Item_result_field
Field *	result_field
Public Attributes inherited from Item
uint	rsize
String	str_value
Item_name_string	item_name
Item_name_string	orig_name
Item *	next
uint32	max_length
int	marker
uint8	decimals
my_bool	maybe_null
my_bool	null_value
my_bool	unsigned_flag
my_bool	with_sum_func
my_bool	fixed
DTCollation	collation
Item_result	cmp_context

Protected Attributes
List< Cached_item > *	left_expr_cache
bool	left_expr_cache_filled
	Whether left_expr_cache holds a value.
bool	need_expr_cache
Item *	expr
Item_in_optimizer *	optimizer
bool	was_null
bool	abort_on_null
Protected Attributes inherited from Item_exists_subselect
bool	value
Protected Attributes inherited from Item_subselect
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	Item_ref_null_helper
class	Item_is_not_null_test
class	Item_in_optimizer
class	subselect_indexsubquery_engine
class	subselect_hash_sj_engine

Additional Inherited Members
Public Types inherited from Item_exists_subselect
enum	enum_exec_method { EXEC_UNSPECIFIED, EXEC_SEMI_JOIN, EXEC_EXISTS, EXEC_EXISTS_OR_MAT, EXEC_MATERIALIZATION }
Static Public Member Functions inherited from Item
static void *	operator new (size_t size) throw ()
static void *	operator new (size_t size, MEM_ROOT *mem_root) throw ()
static void	operator delete (void *ptr, size_t size)
static void	operator delete (void ptr, MEM_ROOT mem_root)
static const CHARSET_INFO *	default_charset ()
Protected Member Functions inherited from Item
String *	val_string_from_real (String *str)
String *	val_string_from_int (String *str)
String *	val_string_from_decimal (String *str)
String *	val_string_from_date (String *str)
String *	val_string_from_datetime (String *str)
String *	val_string_from_time (String *str)
my_decimal *	val_decimal_from_real (my_decimal *decimal_value)
my_decimal *	val_decimal_from_int (my_decimal *decimal_value)
my_decimal *	val_decimal_from_string (my_decimal *decimal_value)
my_decimal *	val_decimal_from_date (my_decimal *decimal_value)
my_decimal *	val_decimal_from_time (my_decimal *decimal_value)
longlong	val_int_from_decimal ()
longlong	val_int_from_date ()
longlong	val_int_from_time ()
longlong	val_int_from_datetime ()
double	val_real_from_decimal ()
bool	get_date_from_string (MYSQL_TIME *ltime, uint flags)
bool	get_date_from_real (MYSQL_TIME *ltime, uint flags)
bool	get_date_from_decimal (MYSQL_TIME *ltime, uint flags)
bool	get_date_from_int (MYSQL_TIME *ltime, uint flags)
bool	get_date_from_time (MYSQL_TIME *ltime)
bool	get_date_from_numeric (MYSQL_TIME *ltime, uint fuzzydate)
bool	get_date_from_non_temporal (MYSQL_TIME *ltime, uint fuzzydate)
bool	get_time_from_string (MYSQL_TIME *ltime)
bool	get_time_from_real (MYSQL_TIME *ltime)
bool	get_time_from_decimal (MYSQL_TIME *ltime)
bool	get_time_from_int (MYSQL_TIME *ltime)
bool	get_time_from_date (MYSQL_TIME *ltime)
bool	get_time_from_datetime (MYSQL_TIME *ltime)
bool	get_time_from_numeric (MYSQL_TIME *ltime)
bool	get_time_from_non_temporal (MYSQL_TIME *ltime)

Detailed Description

Representation of IN subquery predicates of the form "left_expr IN (SELECT ...)".

This class has:

A "subquery execution engine" (as a subclass of Item_subselect) that allows it to evaluate subqueries. (and this class participates in execution by having was_null variable where part of execution result is stored.
Transformation methods (todo: more on this).

This class is not used directly, it is "wrapped" into Item_in_optimizer which provides some small bits of subquery evaluation.

Definition at line 363 of file item_subselect.h.

Member Function Documentation

bool Item_in_subselect::finalize_exists_transform ( SELECT_LEX * select_lex )

Once the decision to use IN->EXISTS has been taken, performs some last steps of this transformation.

Definition at line 142 of file item_subselect.cc.

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bool Item_in_subselect::finalize_materialization_transform ( JOIN * join )

Once the decision to use materialization has been taken, performs some last steps of this transformation.

Definition at line 241 of file item_subselect.cc.

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void Item_in_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_subselect.

Definition at line 2394 of file item_subselect.cc.

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bool Item_in_subselect::init_left_expr_cache ( )

Initialize the cache of the left operand of the IN predicate.

Note: This method has the same purpose as alloc_group_fields(), but it takes a different kind of collection of items, and the list we push to is dynamically allocated.

Return values

TRUE	if a memory allocation error occurred
FALSE	if success

Definition at line 2416 of file item_subselect.cc.

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void Item_in_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_exists_subselect.

Reimplemented in Item_allany_subselect.

Definition at line 2366 of file item_subselect.cc.

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Item_subselect::trans_res Item_in_subselect::row_value_in_to_exists_transformer ( JOIN * join )

Tranform a (possibly non-correlated) IN subquery into a correlated EXISTS.

Todo:: The IF-ELSE below can be refactored so that there is no duplication of the statements that create the new conditions. For this we have to invert the IF and the FOR statements as this: for (each left operand) create the equi-join condition if (is_having_used || !abort_on_null) create the "is null" and is_not_null_test items if (is_having_used) add the equi-join and the null tests to HAVING else add the equi-join and the "is null" to WHERE add the is_not_null_test to HAVING

Definition at line 2010 of file item_subselect.cc.

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Item_subselect::trans_res Item_in_subselect::select_in_like_transformer	(	JOIN *	join,
		Comp_creator *	func
	)

Prepare IN/ALL/ANY/SOME subquery transformation and call appropriate transformation function.

To decide which transformation procedure (scalar or row) applicable here we have to call fix_fields() for left expression to be able to call cols() method on it. Also this method make arena management for underlying transformation methods.

Parameters

join	JOIN object of transforming subquery
func	creator of condition function of subquery

Return values

RES_OK	OK
RES_REDUCE	OK, and current subquery was reduced during transformation
RES_ERROR	Error

Definition at line 2273 of file item_subselect.cc.

Item_subselect::trans_res Item_in_subselect::single_value_in_to_exists_transformer	(	JOIN *	join,
		Comp_creator *	func
	)

Transofrm an IN predicate into EXISTS via predicate injection.

The transformation injects additional predicates into the subquery (and makes the subquery correlated) as follows.

If the subquery has aggregates, GROUP BY, or HAVING, convert to

SELECT ie FROM ... HAVING subq_having AND trigcond(oe $cmp$ ref_or_null_helper<ie>)

the addition is wrapped into trigger only when we want to distinguish between NULL and FALSE results.

Otherwise (no aggregates/GROUP BY/HAVING) convert it to one of the following:

= If we don't need to distinguish between NULL and FALSE subquery:

SELECT 1 FROM ... WHERE (oe $cmp$ ie) AND subq_where

= If we need to distinguish between those:

SELECT 1 FROM ... WHERE subq_where AND trigcond((oe $cmp$ ie) OR (ie IS NULL)) HAVING trigcond(<is_not_null_test>(ie))

At JOIN::optimize() we will compare costs of materialization and EXISTS; if the former is cheaper we will switch to it.

Parameters

join	Join object of the subquery (i.e. 'child' join).
func	Subquery comparison creator

Return values

RES_OK	Either subquery was transformed, or appopriate predicates where injected into it.
RES_REDUCE	The subquery was reduced to non-subquery
RES_ERROR	Error

Definition at line 1712 of file item_subselect.cc.

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bool Item_in_subselect::val_bool ( )

virtual

Todo:: Make this functions class dependent

Reimplemented from Item_exists_subselect.

Definition at line 1396 of file item_subselect.cc.

my_decimal * Item_in_subselect::val_decimal ( my_decimal * decimal_value )

virtual

Return the result of EXISTS as a decimal value

Converts the true/false result into a decimal value. Note that currently this cannot be NULL, so if the query exection fails it will return 0.

Parameters

decimal_value[out] Buffer to hold the resulting decimal value

Return values

Pointer to the converted decimal. Can't be a NULL pointer, as currently EXISTS cannot return NULL.

Reimplemented from Item_exists_subselect.

Definition at line 1409 of file item_subselect.cc.

String * Item_in_subselect::val_str ( String * str )

virtual

Return the result of EXISTS as a string value

Converts the true/false result into a string value. Note that currently this cannot be NULL, so if the query exection fails it will return 0.

Parameters

decimal_value[out] buffer to hold the resulting string value

Return values

Pointer to the converted string. Can't be a NULL pointer, as currently EXISTS cannot return NULL.

Reimplemented from Item_exists_subselect.

Definition at line 1373 of file item_subselect.cc.

Member Data Documentation

bool Item_in_subselect::need_expr_cache

protected

The need for expr cache may be optimized away,

See Also: init_left_expr_cache.

Definition at line 375 of file item_subselect.h.

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

sql/item_subselect.h
sql/item_subselect.cc

Classes

Public Member Functions

Public Attributes

Protected Attributes

Friends

Additional Inherited Members

Detailed Description

Member Function Documentation

Member Data Documentation