Class Item_sum is the base class used for special expressions that SQL calls 'set functions'. More...

#include <item_sum.h>

Inheritance diagram for Item_sum:

Classes
struct	Collect_grouped_aggregate_info
	argument used by walk method collect_grouped_aggregates ("cga") More...

Public Types
enum	Sumfunctype { COUNT_FUNC , COUNT_DISTINCT_FUNC , SUM_FUNC , SUM_DISTINCT_FUNC , AVG_FUNC , AVG_DISTINCT_FUNC , MIN_FUNC , MAX_FUNC , STD_FUNC , VARIANCE_FUNC , SUM_BIT_FUNC , UDF_SUM_FUNC , GROUP_CONCAT_FUNC , JSON_AGG_FUNC , ROW_NUMBER_FUNC , RANK_FUNC , DENSE_RANK_FUNC , CUME_DIST_FUNC , PERCENT_RANK_FUNC , NTILE_FUNC , LEAD_LAG_FUNC , FIRST_LAST_VALUE_FUNC , NTH_VALUE_FUNC , ROLLUP_SUM_SWITCHER_FUNC , GEOMETRY_AGGREGATE_FUNC }

Public Types inherited from Item_func
enum	Functype { UNKNOWN_FUNC , EQ_FUNC , EQUAL_FUNC , NE_FUNC , LT_FUNC , LE_FUNC , GE_FUNC , GT_FUNC , FT_FUNC , MATCH_FUNC , LIKE_FUNC , ISNULL_FUNC , ISNOTNULL_FUNC , ISTRUTH_FUNC , COND_AND_FUNC , COND_OR_FUNC , XOR_FUNC , BETWEEN , IN_FUNC , MULT_EQUAL_FUNC , INTERVAL_FUNC , ISNOTNULLTEST_FUNC , SP_EQUALS_FUNC , SP_DISJOINT_FUNC , SP_INTERSECTS_FUNC , SP_TOUCHES_FUNC , SP_CROSSES_FUNC , SP_WITHIN_FUNC , SP_CONTAINS_FUNC , SP_COVEREDBY_FUNC , SP_COVERS_FUNC , SP_OVERLAPS_FUNC , SP_STARTPOINT , SP_ENDPOINT , SP_EXTERIORRING , SP_POINTN , SP_GEOMETRYN , SP_INTERIORRINGN , NOT_FUNC , NOT_ALL_FUNC , NOW_FUNC , FROM_DAYS_FUNC , TRIG_COND_FUNC , SUSERVAR_FUNC , GUSERVAR_FUNC , COLLATE_FUNC , EXTRACT_FUNC , TYPECAST_FUNC , FUNC_SP , UDF_FUNC , NEG_FUNC , GSYSVAR_FUNC , GROUPING_FUNC , ROLLUP_GROUP_ITEM_FUNC , TABLE_FUNC , DD_INTERNAL_FUNC , PLUS_FUNC , MINUS_FUNC , MUL_FUNC , DIV_FUNC , CEILING_FUNC , ROUND_FUNC , TRUNCATE_FUNC , SQRT_FUNC , ABS_FUNC , POW_FUNC , SIGN_FUNC , FLOOR_FUNC , LOG_FUNC , LN_FUNC , LOG10_FUNC , SIN_FUNC , TAN_FUNC , COS_FUNC , COT_FUNC , DEGREES_FUNC , RADIANS_FUNC , EXP_FUNC , ASIN_FUNC , ATAN_FUNC , ACOS_FUNC , MOD_FUNC , IF_FUNC , NULLIF_FUNC , CASE_FUNC , YEAR_FUNC , YEARWEEK_FUNC , MAKEDATE_FUNC , MONTH_FUNC , MONTHNAME_FUNC , DAY_FUNC , DAYNAME_FUNC , TO_DAYS_FUNC , TO_SECONDS_FUNC , DATE_FUNC , HOUR_FUNC , MINUTE_FUNC , SECOND_FUNC , MICROSECOND_FUNC , DAYOFYEAR_FUNC , ADDTIME_FUNC , QUARTER_FUNC , WEEK_FUNC , WEEKDAY_FUNC , DATEADD_FUNC , FROM_UNIXTIME_FUNC , CONVERT_TZ_FUNC , LAST_DAY_FUNC , UNIX_TIMESTAMP_FUNC , TIME_TO_SEC_FUNC , TIMESTAMPDIFF_FUNC , DATETIME_LITERAL , GREATEST_FUNC , COALESCE_FUNC , LEAST_FUNC , JSON_CONTAINS , JSON_OVERLAPS , JSON_UNQUOTE_FUNC , MEMBER_OF_FUNC , STRCMP_FUNC , TRUE_FUNC , FALSE_FUNC }

enum	optimize_type { OPTIMIZE_NONE , OPTIMIZE_KEY , OPTIMIZE_OP , OPTIMIZE_NULL , OPTIMIZE_EQUAL }

Public Types inherited from Item
enum	Type { INVALID_ITEM = 0 , FIELD_ITEM , FUNC_ITEM , SUM_FUNC_ITEM , STRING_ITEM , INT_ITEM , REAL_ITEM , NULL_ITEM , VARBIN_ITEM , METADATA_COPY_ITEM , FIELD_AVG_ITEM , DEFAULT_VALUE_ITEM , PROC_ITEM , COND_ITEM , REF_ITEM , FIELD_STD_ITEM , FIELD_VARIANCE_ITEM , INSERT_VALUE_ITEM , SUBSELECT_ITEM , ROW_ITEM , CACHE_ITEM , TYPE_HOLDER , PARAM_ITEM , TRIGGER_FIELD_ITEM , DECIMAL_ITEM , XPATH_NODESET , XPATH_NODESET_CMP , VIEW_FIXER_ITEM , FIELD_BIT_ITEM , VALUES_COLUMN_ITEM }

enum	cond_result { COND_UNDEF , COND_OK , COND_TRUE , COND_FALSE }

enum	traverse_order { POSTFIX , PREFIX }

enum	enum_const_item_cache { CACHE_NONE = 0 , CACHE_JSON_VALUE , CACHE_JSON_ATOM }
	How to cache constant JSON data. More...

enum	Bool_test { BOOL_IS_TRUE = 0x00 , BOOL_IS_FALSE = 0x01 , BOOL_IS_UNKNOWN = 0x02 , BOOL_NOT_TRUE = 0x03 , BOOL_NOT_FALSE = 0x04 , BOOL_NOT_UNKNOWN = 0x05 , BOOL_IDENTITY = 0x06 , BOOL_NEGATED = 0x07 , BOOL_ALWAYS_TRUE = 0x08 , BOOL_ALWAYS_FALSE = 0x09 }
	< Modifier for result transformation More...

enum	item_marker { MARKER_NONE = 0 , MARKER_IMPLICIT_NE_ZERO = 1 , MARKER_CONST_PROPAG = 2 , MARKER_BIT = 4 , MARKER_FUNC_DEP_NOT_NULL = 5 , MARKER_DISTINCT_GROUP = 6 , MARKER_COND_DERIVED_TABLE = 7 , MARKER_TRAVERSAL = 8 , MARKER_ICP_COND_USES_INDEX_ONLY = 10 }
	< Values for member 'marker' More...

Public Types inherited from Parse_tree_node_tmpl< Context >
typedef Context	context_t

Public Member Functions
bool	has_force_copy_fields () const

bool	has_with_distinct () const

void	mark_as_sum_func ()

void	mark_as_sum_func (Query_block *)

	Item_sum (const POS &pos, PT_window *w)

	Item_sum (Item *a)

	Item_sum (const POS &pos, Item a, PT_window w)

	Item_sum (const POS &pos, Item a, Item b, PT_window *w)

	Item_sum (const POS &pos, PT_item_list opt_list, PT_window w)

	Item_sum (THD thd, const Item_sum item)
	Copy constructor, need to perform subqueries with temporary tables. More...

bool	itemize (Parse_context pc, Item *res) override
	The same as contextualize() but with additional parameter. More...

Type	type () const override

virtual enum Sumfunctype	sum_func () const =0

virtual enum Sumfunctype	real_sum_func () const

bool	reset_and_add ()
	Resets the aggregate value to its default and aggregates the current value of its attribute(s). More...

virtual void	reset_field ()=0

virtual void	update_field ()=0

virtual bool	keep_field_type () const

bool	resolve_type (THD *) override
	Resolve type-related information for this item, such as result field type, maximum size, precision, signedness, character set and collation. More...

virtual Item *	result_item (Field *field)

table_map	used_tables () const override

table_map	not_null_tables () const override
	Return table map of tables that can't be NULL tables (tables that are used in a context where if they would contain a NULL row generated by a LEFT or RIGHT join, the item would not be true). More...

void	update_used_tables () override
	Updates used tables, not null tables information and accumulates properties up the item tree, cf. More...

void	fix_after_pullout (Query_block parent_query_block, Query_block removed_query_block) override
	Fix after tables have been moved from one query_block level to the parent level, e.g by semijoin conversion. More...

void	add_used_tables_for_aggr_func ()
	Add used_tables information for aggregate function, based on its aggregated query block. More...

bool	is_null () override
	The method allows to determine nullness of a complex expression without fully evaluating it, instead of calling val*() then checking null_value. More...

void	make_const ()

void	print (const THD thd, String str, enum_query_type query_type) const override
	This method is used for to: More...

bool	eq (const Item *item, bool binary_cmp) const override

void	no_rows_in_result () override
	Mark an aggregate as having no rows. More...

virtual void	make_unique ()

virtual Field *	create_tmp_field (bool group, TABLE *table)

bool	collect_grouped_aggregates (uchar *) override

Item *	replace_aggregate (uchar *) override

bool	collect_scalar_subqueries (uchar *) override

bool	collect_item_field_or_view_ref_processor (uchar *) override
	Collects fields and view references that have the qualifying table in the specified query block. More...

bool	clean_up_after_removal (uchar *arg) override
	Remove the item from the list of inner aggregation functions in the Query_block it was moved to by Item_sum::check_sum_func(). More...

bool	aggregate_check_group (uchar *arg) override

bool	aggregate_check_distinct (uchar *arg) override

bool	has_aggregate_ref_in_group_by (uchar *arg) override
	Check if an aggregate is referenced from within the GROUP BY clause of the query block in which it is aggregated. More...

bool	init_sum_func_check (THD *thd)
	Prepare an aggregate function for checking of context. More...

bool	check_sum_func (THD thd, Item *ref)
	Validate the semantic requirements of a set function. More...

Item *	set_arg (THD thd, uint i, Item new_val) override

Item **	get_arg_ptr (uint i)

bool	fix_fields (THD thd, Item *ref) override

virtual void	update_after_wf_arguments_changed (THD *)
	Signal to the function that its arguments may have changed, and that any internal caches etc. More...

virtual bool	aggregator_setup (THD *thd)
	Called to initialize the aggregator. More...

void	aggregator_clear ()
	Called to cleanup the aggregator. More...

bool	aggregator_add ()
	Called to add value to the aggregator. More...

void	set_distinct (bool distinct)

virtual int	set_aggregator (Aggregator::Aggregator_type aggregator)

virtual void	clear ()=0

virtual bool	add ()=0

virtual bool	setup (THD *)

virtual bool	check_wf_semantics1 (THD thd, Query_block select, Window_evaluation_requirements *reqs)
	Only relevant for aggregates qua window functions. More...

virtual bool	check_wf_semantics2 (Window_evaluation_requirements *reqs)
	Like check_wf_semantics1. More...

void	split_sum_func (THD thd, Ref_item_array ref_item_array, mem_root_deque< Item > *fields) override
	See comments in Item_cmp_func::split_sum_func() More...

void	cleanup () override
	Called for every Item after use (preparation and execution). More...

Window *	window ()

const Window *	window () const

bool	reset_wf_state (uchar *arg) override
	Reset execution state for such window function types as determined by arg. More...

virtual bool	framing () const
	All aggregates are framing, i.e. More...

virtual bool	uses_only_one_row () const
	Only for framing window functions. More...

virtual bool	needs_partition_cardinality () const
	Return true if we need to make two passes over the rows in the partition - either because we need the cardinality of it (and we need to read all rows to detect the next partition), or we need to have all partition rows available to evaluate the window function for some other reason, e.g. More...

bool	wf_common_init ()
	Common initial actions for window functions. More...

virtual bool	is_rollup_sum_wrapper () const
	Overridden by Item_rollup_sum_switcher. More...

virtual const Item_sum *	unwrap_sum () const
	In case we are an Item_rollup_sum_switcher, return the underlying Item_sum, otherwise, return this. More...

virtual Item_sum *	unwrap_sum ()
	Non-const version. More...

Public Member Functions inherited from Item_func
virtual uint	argument_count () const

Item **	arguments () const

virtual enum Functype	functype () const

	Item_func ()

	Item_func (const POS &pos)

	Item_func (Item *a)

	Item_func (const POS &pos, Item *a)

	Item_func (Item a, Item b)

	Item_func (const POS &pos, Item a, Item b)

	Item_func (Item a, Item b, Item *c)

	Item_func (const POS &pos, Item a, Item b, Item *c)

	Item_func (Item a, Item b, Item c, Item d)

	Item_func (const POS &pos, Item a, Item b, Item c, Item d)

	Item_func (Item a, Item b, Item c, Item d, Item *e)

	Item_func (const POS &pos, Item a, Item b, Item c, Item d, Item *e)

	Item_func (Item a, Item b, Item c, Item d, Item e, Item f)

	Item_func (const POS &pos, Item a, Item b, Item c, Item d, Item e, Item f)

	Item_func (mem_root_deque< Item * > *list)

	Item_func (const POS &pos, PT_item_list *opt_list)

	Item_func (THD thd, const Item_func item)

virtual Item *	get_arg (uint i)
	Get the i'th argument of the function that this object represents. More...

virtual const Item *	get_arg (uint i) const
	Get the i'th argument of the function that this object represents. More...

bool	fix_func_arg (THD , Item *arg)

virtual bool	resolve_type_inner (THD *)
	Resolve type of function after all arguments have had their data types resolved. More...

bool	propagate_type (THD *thd, const Type_properties &type) override
	Default implementation for all functions: Propagate base_item's type into all arguments. More...

virtual table_map	get_initial_pseudo_tables () const
	Returns the pseudo tables depended upon in order to evaluate this function expression. More...

void	set_used_tables (table_map map)

virtual optimize_type	select_optimize (const THD *)

virtual bool	have_rev_func () const

virtual Item *	key_item () const

bool	set_arguments (mem_root_deque< Item * > *list, bool context_free)
	Copy arguments from list to args array. More...

void	print_op (const THD thd, String str, enum_query_type query_type) const

void	print_args (const THD thd, String str, uint from, enum_query_type query_type) const

virtual void	fix_num_length_and_dec ()

virtual bool	is_deprecated () const

bool	get_arg0_date (MYSQL_TIME *ltime, my_time_flags_t fuzzy_date)

bool	get_arg0_time (MYSQL_TIME *ltime)

void	signal_divide_by_null ()

void	signal_invalid_argument_for_log ()

Field *	tmp_table_field (TABLE *t_arg) override

Item *	get_tmp_table_item (THD *thd) override
	If an Item is materialized in a temporary table, a different Item may have to be used in the part of the query that runs after the materialization. More...

my_decimal *	val_decimal (my_decimal *) override

bool	agg_arg_charsets (DTCollation &c, Item **items, uint nitems, uint flags, int item_sep)

bool	agg_arg_charsets_for_string_result (DTCollation &c, Item **items, uint nitems, int item_sep=1)

bool	agg_arg_charsets_for_comparison (DTCollation &c, Item **items, uint nitems, int item_sep=1)

bool	walk (Item_processor processor, enum_walk walk, uchar *arg) override
	Traverses a tree of Items in prefix and/or postfix order. More...

Item *	transform (Item_transformer transformer, uchar *arg) override
	Transform an Item_func object with a transformer callback function. More...

Item *	compile (Item_analyzer analyzer, uchar *arg_p, Item_transformer transformer, uchar arg_t) override
	Compile Item_func object with a processor and a transformer callback functions. More...

void	traverse_cond (Cond_traverser traverser, void *arg, traverse_order order) override

double	check_float_overflow (double value)
	Throw an error if the input double number is not finite, i.e. More...

longlong	check_integer_overflow (longlong value, bool val_unsigned)
	Throw an error if the input BIGINT value represented by the (longlong value, bool unsigned flag) pair cannot be returned by the function, i.e. More...

int	check_decimal_overflow (int error)
	Throw an error if the error code of a DECIMAL operation is E_DEC_OVERFLOW. More...

bool	has_timestamp_args ()

bool	has_date_args ()

bool	has_time_args ()

bool	has_datetime_args ()

bool	check_valid_arguments_processor (uchar *) override

Item *	gc_subst_transformer (uchar *arg) override
	Transformer function for GC substitution. More...

virtual enum_const_item_cache	can_cache_json_arg (Item *arg)
	Whether an arg of a JSON function can be cached to avoid repetitive string->JSON conversion. More...

virtual bool	contains_only_equi_join_condition () const
	Whether this Item is an equi-join condition. More...

Public Member Functions inherited from Item_result_field
	Item_result_field ()=default

	Item_result_field (const POS &pos)

	Item_result_field (THD thd, const Item_result_field item)

Field *	get_tmp_table_field () override
	If this Item is being materialized into a temporary table, returns the field that is being materialized into. More...

void	set_result_field (Field *field) override

bool	is_result_field () const override

Field *	get_result_field () const override

virtual const char *	func_name () const =0

bool	mark_field_in_map (uchar *arg) override
	Mark underlying field in read or write map of a table. More...

longlong	llrint_with_overflow_check (double realval)

void	raise_numeric_overflow (const char *type_name)

double	raise_float_overflow ()

longlong	raise_integer_overflow ()

int	raise_decimal_overflow ()

Public Member Functions inherited from Item
	Item (const Item &)=delete

void	operator= (Item &)=delete

	Item ()
	Item constructor for general use. More...

	Item (THD thd, const Item item)
	Constructor used by Item_field, Item_ref & aggregate functions. More...

	Item (const POS &)
	Parse-time context-independent constructor. More...

	~Item () override=default

void	rename (char *new_name)
	rename item (used for views, cleanup() return original name). More...

void	init_make_field (Send_field *tmp_field, enum enum_field_types type)

virtual void	notify_removal ()
	Called when an item has been removed, can be used to notify external objects about the removal, e.g subquery predicates that are part of the sj_candidates container. More...

virtual void	make_field (Send_field *field)

virtual Field *	make_string_field (TABLE *table) const
	Create a field to hold a string value from an item. More...

void	quick_fix_field ()

virtual void	set_can_use_prefix_key ()

bool	propagate_type (THD *thd, enum_field_types def=MYSQL_TYPE_VARCHAR, bool pin=false, bool inherit=false)
	Wrapper for easier calling of propagate_type(const Type_properties &). More...

virtual void	mark_json_as_scalar ()
	For Items with data type JSON, mark that a string argument is treated as a scalar JSON value. More...

virtual std::optional< ContainedSubquery >	get_contained_subquery (const Query_block *outer_query_block)
	If this item represents a IN/ALL/ANY/comparison_operator subquery, return that (along with data on how it will be executed). More...

type_conversion_status	save_in_field_no_warnings (Field *field, bool no_conversions)
	Save the item into a field but do not emit any warnings. More...

type_conversion_status	save_in_field (Field *field, bool no_conversions)
	Save a temporal value in packed longlong format into a Field. More...

void	save_in_field_no_error_check (Field *field, bool no_conversions)
	A slightly faster value of save_in_field() that returns no error value (you will need to check thd->is_error() yourself), and does not support saving into hidden fields for functional indexes. More...

virtual void	save_org_in_field (Field *field)

virtual bool	send (Protocol protocol, String str)
	This is only called from items that is not of type item_field. More...

bool	evaluate (THD thd, String str)
	Evaluate item, possibly using the supplied buffer. More...

virtual Item_result	result_type () const

virtual Item_result	numeric_context_result_type () const
	Result type when an item appear in a numeric context. More...

Item_result	temporal_with_date_as_number_result_type () const
	Similar to result_type() but makes DATE, DATETIME, TIMESTAMP pretend to be numbers rather than strings. More...

virtual void	set_data_type_inherited ()
	Set data type for item as inherited. More...

virtual void	pin_data_type ()
	Pin the data type for the item. More...

enum_field_types	data_type () const
	Retrieve the derived data type of the Item. More...

virtual enum_field_types	actual_data_type () const
	Retrieve actual data type for an item. More...

virtual enum_field_types	default_data_type () const
	Get the default data (output) type for the specific item. More...

void	set_data_type (enum_field_types data_type)
	Set the data type of the current Item. More...

void	set_data_type_null ()

void	set_data_type_bool ()

void	set_data_type_longlong ()
	Set the data type of the Item to be longlong. More...

void	set_data_type_decimal (uint8 precision, uint8 scale)
	Set the data type of the Item to be decimal. More...

void	set_data_type_double ()
	Set the data type of the Item to be double precision floating point. More...

void	set_data_type_float ()
	Set the data type of the Item to be single precision floating point. More...

void	set_data_type_string (uint32 max_l)
	Set the Item to be variable length string. More...

void	set_data_type_string (ulonglong max_char_length_arg)
	Set the Item to be variable length string. More...

void	set_data_type_string (uint32 max_l, const CHARSET_INFO *cs)
	Set the Item to be variable length string. More...

void	set_data_type_string (uint32 max_l, const DTCollation &coll)
	Set the Item to be variable length string. More...

void	set_data_type_char (uint32 max_l)
	Set the Item to be fixed length string. More...

void	set_data_type_char (uint32 max_l, const CHARSET_INFO *cs)
	Set the Item to be fixed length string. More...

void	set_data_type_blob (uint32 max_l)
	Set the Item to be of BLOB type. More...

void	set_data_type_date ()
	Set all type properties for Item of DATE type. More...

void	set_data_type_time (uint8 fsp)
	Set all type properties for Item of TIME type. More...

void	set_data_type_datetime (uint8 fsp)
	Set all properties for Item of DATETIME type. More...

void	set_data_type_timestamp (uint8 fsp)
	Set all properties for Item of TIMESTAMP type. More...

void	set_data_type_geometry ()
	Set the data type of the Item to be GEOMETRY. More...

void	set_data_type_json ()
	Set the data type of the Item to be JSON. More...

void	set_data_type_year ()
	Set the data type of the Item to be YEAR. More...

void	set_data_type_bit ()
	Set the data type of the Item to be bit. More...

void	set_data_type_from_item (const Item *item)
	Set data type properties of the item from the properties of another item. More...

virtual TYPELIB *	get_typelib () const
	Get the typelib information for an item of type set or enum. More...

virtual Item_result	cast_to_int_type () const

void	aggregate_type (Bounds_checked_array< Item * > items)
	Aggregates data types from array of items into current item. More...

virtual enum_monotonicity_info	get_monotonicity_info () const

virtual longlong	val_int_endpoint (bool left_endp, bool *incl_endp)

virtual double	val_real ()=0

virtual longlong	val_int ()=0

virtual longlong	val_date_temporal ()
	Return date value of item in packed longlong format. More...

virtual longlong	val_time_temporal ()
	Return time value of item in packed longlong format. More...

longlong	val_temporal_by_field_type ()
	Return date or time value of item in packed longlong format, depending on item field type. More...

longlong	int_sort_key ()
	Produces a key suitable for filesort. More...

longlong	val_temporal_with_round (enum_field_types type, uint8 dec)
	Get date or time value in packed longlong format. More...

ulonglong	val_uint ()

virtual String *	val_str (String *str)=0

virtual String *	val_str_ascii (String *str)

virtual bool	val_bool ()

virtual bool	val_json (Json_wrapper *result)
	Get a JSON value from an Item. More...

virtual float	get_filtering_effect (THD thd, table_map filter_for_table, table_map read_tables, const MY_BITMAP fields_to_ignore, double rows_in_table)
	Calculate the filter contribution that is relevant for table 'filter_for_table' for this item. More...

bool	error_json ()
	Get the value to return from val_json() in case of errors. More...

bool	get_date_from_non_temporal (MYSQL_TIME *ltime, my_time_flags_t fuzzydate)
	Convert a non-temporal type to date. More...

bool	get_time_from_non_temporal (MYSQL_TIME *ltime)
	Convert a non-temporal type to time. More...

my_decimal *	error_decimal (my_decimal *decimal_value)
	Get the value to return from val_decimal() in case of errors. More...

String *	error_str ()
	Get the value to return from val_str() in case of errors. More...

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 bool	basic_const_item () const
	Returns true if this is a simple constant item like an integer, not a constant expression. More...

bool	may_eval_const_item (const THD *thd) const

virtual Item *	clone_item () const

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 ()
	TIME precision of the item: 0..6. More...

virtual uint	datetime_precision ()
	DATETIME precision of the item: 0..6. More...

bool	const_item () const
	Returns true if item is constant, regardless of query evaluation state. More...

bool	const_for_execution () const
	Returns true if item is constant during one query execution. More...

bool	may_evaluate_const (const THD *thd) const
	Return true if this is a const item that may be evaluated in the current phase of statement processing. More...

bool	is_non_deterministic () const

bool	is_outer_reference () const

void	print_item_w_name (const THD thd, String , enum_query_type query_type) const

void	print_for_order (const THD thd, String str, enum_query_type query_type, bool used_alias) const
	Prints the item when it's part of ORDER BY and GROUP BY. More...

void	split_sum_func2 (THD thd, Ref_item_array ref_item_array, mem_root_deque< Item > fields, Item *ref, bool skip_registered)

virtual bool	get_date (MYSQL_TIME *ltime, my_time_flags_t fuzzydate)=0

virtual bool	get_time (MYSQL_TIME *ltime)=0

virtual bool	get_timeval (my_timeval tm, int warnings)
	Get timestamp in "struct timeval" format. More...

bool	update_null_value ()
	Make sure the null_value member has a correct value. More...

virtual void	apply_is_true ()
	Apply the IS TRUE truth property, meaning that an UNKNOWN result and a FALSE result are treated the same. More...

virtual bool	is_bool_func () const

virtual Item *	copy_or_same (THD *)

virtual Item *	copy_andor_structure (THD *)

virtual Item *	real_item ()

virtual const Item *	real_item () const

virtual const CHARSET_INFO *	compare_collation () const

virtual const CHARSET_INFO *	charset_for_protocol ()

template<class T >
auto	walk_helper_thunk (uchar *arg)

template<class T >
auto	analyze_helper_thunk (uchar **arg)
	See CompileItem. More...

virtual bool	intro_version (uchar *)

bool	cleanup_processor (uchar *)
	cleanup() item if it is resolved ('fixed'). More...

virtual bool	collect_item_field_processor (uchar *)

virtual bool	collect_item_field_or_ref_processor (uchar *)

virtual bool	add_field_to_set_processor (uchar *)
	Item::walk function. More...

virtual bool	visitor_processor (uchar *arg)
	A processor to handle the select lex visitor framework. More...

virtual bool	add_field_to_cond_set_processor (uchar *)
	Item::walk function. More...

virtual bool	remove_column_from_bitmap (uchar *arg)
	Visitor interface for removing all column expressions (Item_field) in this expression tree from a bitmap. More...

virtual bool	find_item_in_field_list_processor (uchar *)

virtual bool	change_context_processor (uchar *)

virtual bool	find_item_processor (uchar *arg)

virtual bool	find_field_processor (uchar *)
	Is this an Item_field which references the given Field argument? More...

virtual bool	cast_incompatible_args (uchar *)
	Wrap incompatible arguments in CAST nodes to the expected data types. More...

virtual bool	used_tables_for_level (uchar *arg)
	Return used table information for the specified query block (level). More...

virtual bool	check_column_privileges (uchar *thd)
	Check privileges. More...

virtual bool	inform_item_in_cond_of_tab (uchar *)

virtual void	bind_fields ()
	Bind objects from the current execution context to field objects in item trees. More...

virtual bool	is_strong_side_column_not_in_fd (uchar *)

virtual bool	is_column_not_in_fd (uchar *)

virtual Bool3	local_column (const Query_block *) const

virtual bool	collect_subqueries (uchar *)

virtual bool	update_depended_from (uchar *)

bool	visit_all_analyzer (uchar **)

virtual bool	cache_const_expr_analyzer (uchar **cache_item)
	Check if an item is a constant one and can be cached. More...

Item *	cache_const_expr_transformer (uchar *item)
	Cache item if needed. More...

virtual bool	equality_substitution_analyzer (uchar **)

virtual Item *	equality_substitution_transformer (uchar *)

virtual bool	check_partition_func_processor (uchar *)
	Check if a partition function is allowed. More...

virtual bool	subst_argument_checker (uchar **arg)

virtual bool	explain_subquery_checker (uchar **)

virtual Item *	explain_subquery_propagator (uchar *)

virtual Item *	equal_fields_propagator (uchar *)

virtual bool	disable_constant_propagation (uchar *)

virtual Item *	replace_equal_field (uchar *)

virtual bool	check_gcol_depend_default_processor (uchar *args)
	Check if a generated expression depends on DEFAULT function with specific column name as argument. More...

virtual Item *	replace_with_derived_expr (uchar *arg)
	Assuming this expression is part of a condition that would be pushed to the WHERE clause of a materialized derived table, replace, in this expression, each derived table's column with a clone of the expression lying under it in the derived table's definition. More...

virtual Item *	replace_with_derived_expr_ref (uchar *arg)
	Assuming this expression is part of a condition that would be pushed to the HAVING clause of a materialized derived table, replace, in this expression, each derived table's column with a reference to the expression lying under it in the derived table's definition. More...

virtual Item *	replace_view_refs_with_clone (uchar *arg)
	Assuming this expression is part of a condition that would be pushed to a materialized derived table, replace, in this expression, each view reference with a clone of the expression in merged derived table's definition. More...

virtual Item *	this_item ()

virtual const Item *	this_item () const

virtual Item **	this_item_addr (THD , Item *addr_arg)

virtual uint	cols () const

virtual Item *	element_index (uint)

virtual Item **	addr (uint)

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) const
	Create a field based on field_type of argument. More...

virtual Item_field *	field_for_view_update ()

virtual Item *	truth_transformer (THD *thd, Bool_test test)
	Informs an item that it is wrapped in a truth test, in case it wants to transforms itself to implement this test by itself. More...

virtual Item *	update_value_transformer (uchar *)

virtual Item *	replace_scalar_subquery (uchar *)
	When walking the item tree seeing an Item_singlerow_subselect matching a target, replace it with a substitute field used when transforming scalar subqueries into derived tables. More...

virtual Item *	replace_item_field (uchar *)
	Transform processor used by Query_block::transform_grouped_to_derived to replace fields which used to be at the transformed query block with corresponding fields in the new derived table containing the grouping operation of the original transformed query block. More...

virtual Item *	replace_item_view_ref (uchar *)

virtual Item *	replace_outer_ref (uchar *)

virtual bool	update_aggr_refs (uchar *)
	A walker processor overridden by Item_aggregate_ref, q.v. More...

virtual Item *	safe_charset_converter (THD thd, const CHARSET_INFO tocs)

void	delete_self ()
	Delete this item. More...

virtual bool	is_splocal () const

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
	Check whether this and the given item has compatible comparison context. More...

virtual Field::geometry_type	get_geometry_type () const

String *	check_well_formed_result (String *str, bool send_error, bool truncate)
	Verifies that the input string is well-formed according to its character set. More...

bool	eq_by_collation (Item item, bool binary_cmp, const CHARSET_INFO cs)

virtual bool	is_expensive ()

uint32	max_char_length () const

uint32	max_char_length (const CHARSET_INFO *cs) const

void	fix_char_length (uint32 max_char_length_arg)

virtual bool	is_outer_field () const

bool	is_blob_field () const
	Check if an item either is a blob field, or will be represented as a BLOB field if a field is created based on this item. More...

uint	reference_count () const

void	increment_ref_count ()
	Increment reference count. More...

uint	decrement_ref_count ()
	Decrement reference count. More...

bool	has_subquery () const

bool	has_stored_program () const

bool	has_aggregation () const

void	set_aggregation ()
	Set the "has aggregation" property. More...

void	reset_aggregation ()
	Reset the "has aggregation" property. More...

bool	has_wf () const

void	set_wf ()
	Set the "has window function" property. More...

bool	has_rollup_expr () const

void	set_rollup_expr ()
	Set the property: this item (tree) contains a reference to a ROLLUP expr. More...

bool	has_grouping_func () const

void	set_grouping_func ()
	Set the property: this item is a call to GROUPING. More...

virtual bool	created_by_in2exists () const
	Whether this Item was created by the IN->EXISTS subquery transformation. More...

void	mark_subqueries_optimized_away ()

virtual bool	gc_subst_analyzer (uchar **)
	Analyzer function for GC substitution. More...

virtual bool	replace_field_processor (uchar *)
	A processor that replaces any Fields with a Create_field_wrapper. More...

bool	can_be_substituted_for_gc (bool array=false) const
	Check if this item is of a type that is eligible for GC substitution. More...

void	aggregate_decimal_properties (Item **item, uint nitems)
	Set precision and decimals of function when this depends on arguments' values for these quantities. More...

void	aggregate_float_properties (Item **item, uint nitems)
	Set max_length and decimals of function if function is floating point and result length/precision depends on argument ones. More...

void	aggregate_char_length (Item **args, uint nitems)
	Set the maximum number of characters required by any of the items in args. More...

void	aggregate_temporal_properties (Item **item, uint nitems)
	Set fractional seconds precision for temporal functions. More...

bool	aggregate_string_properties (const char name, Item *item, uint nitems)
	Aggregate string properties (character set, collation and maximum length) for string function. More...

void	aggregate_num_type (Item_result result_type, Item **item, uint nitems)
	This function is used to resolve type for numeric result type of CASE, COALESCE, IF and LEAD/LAG. More...

virtual bool	repoint_const_outer_ref (uchar *arg)
	This function applies only to Item_field objects referred to by an Item_ref object that has been marked as a const_item. More...

virtual bool	strip_db_table_name_processor (uchar *)

bool	is_abandoned () const

bool	is_nullable () const

void	set_nullable (bool nullable)

virtual bool	supports_partial_update (const Field_json *field) const
	Check if this expression can be used for partial update of a given JSON column. More...

virtual bool	returns_array () const
	Whether the item returns array of its data type. More...

virtual void	allow_array_cast ()
	A helper function to ensure proper usage of CAST(. More...

Public Member Functions inherited from Parse_tree_node_tmpl< Context >
virtual	~Parse_tree_node_tmpl ()=default

bool	is_contextualized () const

virtual bool	contextualize (Context *pc)
	Do all context-sensitive things and mark the node as contextualized. More...

void	error (Context *pc, const POS &pos) const
	syntax_error() function replacement for deferred reporting of syntax errors More...

void	error (Context pc, const POS &pos, const char msg) const
	syntax_error() function replacement for deferred reporting of syntax errors More...

void	errorf (Context pc, const POS &pos, const char format,...) const
	syntax_error() function replacement for deferred reporting of syntax errors More...

Public Attributes
Item **	referenced_by [2]
	For a group aggregate which is aggregated into an outer query block; none, or just the first or both cells may be non-zero. More...

Item_sum *	next_sum {nullptr}
	next in the circular chain of registered objects More...

Item_sum *	in_sum_func
	the containing set function if any More...

Query_block *	base_query_block
	query block where function is placed More...

Query_block *	aggr_query_block
	For a group aggregate, query block where function is aggregated. More...

int8	max_aggr_level
	max level of unbound column references More...

int8	max_sum_func_level
	max level of aggregation for contained functions More...

bool	allow_group_via_temp_table
	If incremental update of fields is supported. More...

nesting_map	save_deny_window_func
	WFs are forbidden when resolving Item_sum; this member is used to restore WF allowance status afterwards. More...

Public Attributes inherited from Item_func
uint	arg_count
	How many arguments in 'args'. More...

Public Attributes inherited from Item
Item *	next_free
	Intrusive list pointer for free list. More...

DTCollation	collation
	Character set and collation properties assigned for this Item. More...

Item_name_string	item_name
	Name from query. More...

Item_name_string	orig_name
	Original item name (if it was renamed) More...

uint32	max_length
	Maximum length of result of evaluating this item, in number of bytes. More...

item_marker	marker
	This member has several successive meanings, depending on the phase we're in (. More...

Item_result	cmp_context
	Comparison context. More...

bool	fixed
	True if item has been resolved. More...

uint8	decimals
	Number of decimals in result when evaluating this item. More...

bool	null_value
	True if item is null. More...

bool	unsigned_flag

bool	m_is_window_function
	True if item represents window func. More...

bool	hidden {false}
	If the item is in a SELECT list (Query_block::fields) and hidden is true, the item wasn't actually in the list as given by the user (it was added by the optimizer, to e.g. More...

bool	m_in_check_constraint_exec_ctx {false}
	True if item is a top most element in the expression being evaluated for a check constraint. More...

Protected Member Functions
void	unsupported_as_wf ()

Protected Member Functions inherited from Item_func
bool	param_type_uses_non_param (THD *thd, enum_field_types def=MYSQL_TYPE_VARCHAR)

bool	param_type_is_default (THD *thd, uint start, uint end, uint step, enum_field_types def)
	For arguments of this Item_func ("args" array), in range [start, start+step, start+2*step,...,end[ : if they're a PS parameter with invalid (not known) type, give them default type "def". More...

bool	param_type_is_default (THD *thd, uint start, uint end, enum_field_types def=MYSQL_TYPE_VARCHAR)

bool	param_type_is_rejected (uint start, uint end)
	For arguments of this Item_func ("args" array), in range [start,end[ : sends error if they're a dynamic parameter. More...

const Item_field *	contributes_to_filter (table_map read_tables, table_map filter_for_table, const MY_BITMAP *fields_to_ignore) const
	Whether or not an item should contribute to the filtering effect (. More...

virtual bool	may_have_named_parameters () const
	Named parameters are allowed in a parameter list. More...

bool	is_non_const_over_literals (uchar *) override

bool	check_function_as_value_generator (uchar *checker_args) override
	Check if this item is allowed for a virtual column or inside a default expression. More...

bool	is_valid_for_pushdown (uchar *arg) override
	Check if all the columns present in this expression are from the derived table. More...

bool	check_column_in_window_functions (uchar *arg) override
	Check if all the columns present in this expression are present in PARTITION clause of window functions of the derived table. More...

bool	check_column_in_group_by (uchar *arg) override
	Check if all the columns present in this expression are present in GROUP BY clause of the derived table. More...

longlong	val_int_from_real ()

Protected Member Functions inherited from Item
String *	make_empty_result ()
	Sets the result value of the function an empty string, using the current character set. More...

bool	skip_itemize (Item **res)
	Helper function to skip itemize() for grammar-allocated items. More...

virtual type_conversion_status	save_in_field_inner (Field *field, bool no_conversions)
	Helper function which does all of the work for save_in_field(Field*, bool), except some error checking common to all subclasses, which is performed by save_in_field() itself. More...

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 ()

longlong	val_int_from_string ()

double	val_real_from_decimal ()

double	val_real_from_string ()

bool	error_bool ()
	Get the value to return from val_bool() in case of errors. More...

int	error_int ()
	Get the value to return from val_int() in case of errors. More...

double	error_real ()
	Get the value to return from val_real() in case of errors. More...

bool	error_date ()
	Get the value to return from get_date() in case of errors. More...

bool	error_time ()
	Get the value to return from get_time() in case of errors. More...

String *	null_return_str ()
	Gets the value to return from val_str() when returning a NULL value. More...

bool	get_date_from_string (MYSQL_TIME *ltime, my_time_flags_t flags)
	Convert val_str() to date in MYSQL_TIME. More...

bool	get_date_from_real (MYSQL_TIME *ltime, my_time_flags_t flags)
	Convert val_real() to date in MYSQL_TIME. More...

bool	get_date_from_decimal (MYSQL_TIME *ltime, my_time_flags_t flags)
	Convert val_decimal() to date in MYSQL_TIME. More...

bool	get_date_from_int (MYSQL_TIME *ltime, my_time_flags_t flags)
	Convert val_int() to date in MYSQL_TIME. More...

bool	get_date_from_time (MYSQL_TIME *ltime)
	Convert get_time() from time to date in MYSQL_TIME. More...

bool	get_date_from_numeric (MYSQL_TIME *ltime, my_time_flags_t fuzzydate)
	Convert a numeric type to date. More...

bool	get_time_from_string (MYSQL_TIME *ltime)
	Convert val_str() to time in MYSQL_TIME. More...

bool	get_time_from_real (MYSQL_TIME *ltime)
	Convert val_real() to time in MYSQL_TIME. More...

bool	get_time_from_decimal (MYSQL_TIME *ltime)
	Convert val_decimal() to time in MYSQL_TIME. More...

bool	get_time_from_int (MYSQL_TIME *ltime)
	Convert val_int() to time in MYSQL_TIME. More...

bool	get_time_from_date (MYSQL_TIME *ltime)
	Convert date to time. More...

bool	get_time_from_datetime (MYSQL_TIME *ltime)
	Convert datetime to time. More...

bool	get_time_from_numeric (MYSQL_TIME *ltime)
	Convert a numeric type to time. More...

virtual longlong	val_date_temporal_at_utc ()

virtual longlong	val_time_temporal_at_utc ()

void	set_accum_properties (const Item *item)
	Set accumulated properties for an Item. More...

void	add_accum_properties (const Item *item)
	Add more accumulated properties to an Item. More...

void	set_subquery ()
	Set the "has subquery" property. More...

void	set_stored_program ()
	Set the "has stored program" property. More...

Protected Member Functions inherited from Parse_tree_node_tmpl< Context >
	Parse_tree_node_tmpl ()

Static Protected Member Functions
static ulonglong	ram_limitation (THD *thd)
	Calculate the affordable RAM limit for structures like TREE or Unique used in Item_sum_*. More...

Static Protected Member Functions inherited from Item
static bool	bit_func_returns_binary (const Item a, const Item b)

static bool	mark_field_in_map (Mark_field mark_field, Field field)
	Helper function for mark_field_in_map(uchar *arg). More...

Protected Attributes
Aggregator *	aggr {nullptr}
	Aggregator class instance. More...

PT_window *	m_window {nullptr}
	If sum is a window function, this field contains the window. More...

bool	m_window_resolved {false}
	True if we have already resolved this window functions window reference. More...

bool	forced_const {false}
	True means that this field has been evaluated during optimization. More...

bool	m_null_resolved {false}
	true if the function is resolved to be always NULL More...

bool	m_null_executed {false}
	true if the function is determined to be NULL at start of execution More...

Protected Attributes inherited from Item_func
Item **	args
	Array of pointers to arguments. More...

bool	null_on_null {true}
	Affects how to determine that NULL argument implies a NULL function return. More...

uint	allowed_arg_cols {1}

table_map	used_tables_cache {0}
	Value used in calculation of result of used_tables() More...

table_map	not_null_tables_cache {0}
	Value used in calculation of result of not_null_tables() More...

Protected Attributes inherited from Item_result_field
Field *	result_field {nullptr}

Protected Attributes inherited from Item
String	str_value
	str_values's main purpose is to cache the value in save_in_field More...

uint8	m_accum_properties

Private Attributes
bool	force_copy_fields {false}
	Used in making ROLLUP. More...

bool	with_distinct {false}
	Indicates how the aggregate function was specified by the parser : true if it was written as AGGREGATE(DISTINCT), false if it was AGGREGATE() More...

Friends
class	Aggregator_distinct

class	Aggregator_simple

Additional Inherited Members
Static Public Member Functions inherited from Item
static void *	operator new (size_t size) noexcept

static void *	operator new (size_t size, MEM_ROOT *mem_root, const std::nothrow_t &arg=std::nothrow) noexcept

static void	operator delete (void *ptr, size_t size)

static void	operator delete (void , MEM_ROOT , const std::nothrow_t &) noexcept

static enum_field_types	result_to_type (Item_result result)

static Item_result	type_to_result (enum_field_types type)

static enum_field_types	type_for_variable (enum_field_types src_type)
	Provide data type for a user or system variable, based on the type of the item that is assigned to the variable. More...

static enum_field_types	string_field_type (uint32 max_bytes)
	Determine correct string field type, based on string length. More...

static const CHARSET_INFO *	default_charset ()

Static Public Member Functions inherited from Parse_tree_node_tmpl< Context >
static void *	operator new (size_t size, MEM_ROOT *mem_root, const std::nothrow_t &arg=std::nothrow) noexcept

static void	operator delete (void *ptr, size_t size)

static void	operator delete (void , MEM_ROOT , const std::nothrow_t &) noexcept

Static Protected Attributes inherited from Item
static constexpr uint8	PROP_SUBQUERY = 0x01
	Set of properties that are calculated by accumulation from underlying items. More...

static constexpr uint8	PROP_STORED_PROGRAM = 0x02

static constexpr uint8	PROP_AGGREGATION = 0x04

static constexpr uint8	PROP_WINDOW_FUNCTION = 0x08

static constexpr uint8	PROP_ROLLUP_EXPR = 0x10
	Set if the item or one or more of the underlying items contains a ROLLUP expression. More...

static constexpr uint8	PROP_GROUPING_FUNC = 0x20
	Set if the item or one or more of the underlying items is a GROUPING function. More...

Detailed Description

Class Item_sum is the base class used for special expressions that SQL calls 'set functions'.

These expressions are formed with the help of aggregate functions such as SUM, MAX, GROUP_CONCAT etc. Class Item_sum is also the base class for Window functions; the text below first documents set functions, then window functions.

GENERAL NOTES

A set function cannot be used in all positions where expressions are accepted. There are some quite explicable restrictions for the use of set functions.

In the query:

SELECT AVG(b) FROM t1 WHERE SUM(b) > 20 GROUP by a

the set function AVG(b) is valid, while the usage of SUM(b) is invalid. A WHERE condition must contain expressions that can be evaluated for each row of the table. Yet the expression SUM(b) can be evaluated only for each group of rows with the same value of column a. In the query:

SELECT AVG(b) FROM t1 WHERE c > 30 GROUP BY a HAVING SUM(b) > 20

both set function expressions AVG(b) and SUM(b) are valid.

We can say that in a query without nested selects an occurrence of a set function in an expression of the SELECT list or/and in the HAVING clause is valid, while in the WHERE clause, FROM clause or GROUP BY clause it is invalid.

The general rule to detect whether a set function is valid in a query with nested subqueries is much more complicated.

Consider the following query:

SELECT t1.a FROM t1 GROUP BY t1.a HAVING t1.a > ALL (SELECT t2.c FROM t2 WHERE SUM(t1.b) < t2.c).

The set function SUM(b) is used here in the WHERE clause of the subquery. Nevertheless it is valid since it is contained in the HAVING clause of the outer query. The expression SUM(t1.b) is evaluated for each group defined in the main query, not for groups of the subquery.

The problem of finding the query where to aggregate a particular set function is not so simple as it seems to be.

In the query: SELECT t1.a FROM t1 GROUP BY t1.a HAVING t1.a > ALL(SELECT t2.c FROM t2 GROUP BY t2.c HAVING SUM(t1.a) < t2.c)

the set function can be evaluated in both the outer and the inner query block. If we evaluate SUM(t1.a) for the outer query then we get the value of t1.a multiplied by the cardinality of a group in table t1. In this case, SUM(t1.a) is used as a constant value in each correlated subquery. But SUM(t1.a) can also be evaluated for the inner query. In this case t1.a will be a constant value for each correlated subquery and summation is performed for each group of table t2. (Here it makes sense to remind that the query

SELECT c FROM t GROUP BY a HAVING SUM(1) < a

is quite valid in our SQL).

So depending on what query block we assign the set function to we can get different results.

The general rule to detect the query block Q where a set function will be aggregated (evaluated) can be formulated as follows.

Reference: SQL2011 <set function specification> syntax rules 6 and 7.

Consider a set function S(E) where E is an expression which contains column references C1, ..., Cn. Resolve all column references Ci against the query block Qi containing the set function S(E). Let Q be the innermost query block of all query blocks Qi. (It should be noted here that S(E) in no way can be aggregated in the query block containing the subquery Q, otherwise S(E) would refer to at least one unbound column reference). If S(E) is used in a construct of Q where set functions are allowed then we aggregate S(E) in Q. Otherwise:

if ANSI SQL mode is enabled (MODE_ANSI), then report an error.
otherwise, look for the innermost query block containing S(E) of those where usage of S(E) is allowed. The place of aggregation depends on which clause the subquery is contained within; It will be different when contained in a WHERE clause versus in the select list or in HAVING clause.

Let's demonstrate how this rule is applied to the following queries.

SELECT t1.a FROM t1 GROUP BY t1.a HAVING t1.a > ALL(SELECT t2.b FROM t2 GROUP BY t2.b HAVING t2.b > ALL(SELECT t3.c FROM t3 GROUP BY t3.c HAVING SUM(t1.a+t2.b) < t3.c)) For this query the set function SUM(t1.a+t2.b) contains t1.a and t2.b with t1.a defined in the outermost query, and t2.b defined for its subquery. The set function is contained in the HAVING clause of the subquery and can be evaluated in this subquery.
SELECT t1.a FROM t1 GROUP BY t1.a HAVING t1.a > ALL(SELECT t2.b FROM t2 WHERE t2.b > ALL (SELECT t3.c FROM t3 GROUP BY t3.c HAVING SUM(t1.a+t2.b) < t3.c)) The set function SUM(t1.a+t2.b) is contained in the WHERE clause of the second query block - the outermost query block where t1.a and t2.b are defined. If we evaluate the function in this subquery we violate the context rules. So we evaluate the function in the third query block (over table t3) where it is used under the HAVING clause; if in ANSI SQL mode, an error is thrown.
SELECT t1.a FROM t1 GROUP BY t1.a HAVING t1.a > ALL(SELECT t2.b FROM t2 WHERE t2.b > ALL (SELECT t3.c FROM t3 WHERE SUM(t1.a+t2.b) < t3.c)) In this query, evaluation of SUM(t1.a+t2.b) is not valid neither in the second nor in the third query block.

Set functions can generally not be nested. In the query

SELECT t1.a from t1 GROUP BY t1.a HAVING AVG(SUM(t1.b)) > 20

the expression SUM(b) is not valid, even though it is contained inside a HAVING clause. However, it is acceptable in the query:

SELECT t.1 FROM t1 GROUP BY t1.a HAVING SUM(t1.b) > 20.

An argument of a set function does not have to be a simple column reference as seen in examples above. This can be a more complex expression

SELECT t1.a FROM t1 GROUP BY t1.a HAVING SUM(t1.b+1) > 20.

The expression SUM(t1.b+1) has clear semantics in this context: we sum up the values of t1.b+1 where t1.b varies for all values within a group of rows that contain the same t1.a value.

A set function for an outer query yields a constant value within a subquery. So the semantics of the query

SELECT t1.a FROM t1 GROUP BY t1.a HAVING t1.a IN (SELECT t2.c FROM t2 GROUP BY t2.c HAVING AVG(t2.c+SUM(t1.b)) > 20)

is still clear. For a group of rows with the same value for t1.a, calculate the value of SUM(t1.b) as 's'. This value is substituted in the subquery:

SELECT t2.c FROM t2 GROUP BY t2.c HAVING AVG(t2.c+s)

By the same reason the following query with a subquery

SELECT t1.a FROM t1 GROUP BY t1.a HAVING t1.a IN (SELECT t2.c FROM t2 GROUP BY t2.c HAVING AVG(SUM(t1.b)) > 20) is also valid.

IMPLEMENTATION NOTES

The member base_query_block contains a reference to the query block that the set function is contained within.

The member aggr_query_block contains a reference to the query block where the set function is aggregated.

The field max_aggr_level holds the maximum of the nest levels of the unbound column references contained in the set function. A column reference is unbound within a set function if it is not bound by any subquery used as a subexpression in this function. A column reference is bound by a subquery if it is a reference to the column by which the aggregation of some set function that is used in the subquery is calculated. For the set function used in the query

SELECT t1.a FROM t1 GROUP BY t1.a HAVING t1.a > ALL(SELECT t2.b FROM t2 GROUP BY t2.b HAVING t2.b > ALL(SELECT t3.c FROM t3 GROUP BY t3.c HAVING SUM(t1.a+t2.b) < t3.c))

the value of max_aggr_level is equal to 1 since t1.a is bound in the main query, and t2.b is bound by the first subquery whose nest level is 1. Obviously a set function cannot be aggregated in a subquery whose nest level is less than max_aggr_level. (Yet it can be aggregated in the subqueries whose nest level is greater than max_aggr_level.) In the query SELECT t1.a FROM t1 HAVING AVG(t1.a+(SELECT MIN(t2.c) FROM t2))

the value of the max_aggr_level for the AVG set function is 0 since the reference t2.c is bound in the subquery.

If a set function contains no column references (like COUNT(*)), max_aggr_level is -1.

The field 'max_sum_func_level' is to contain the maximum of the nest levels of the set functions that are used as subexpressions of the arguments of the given set function, but not aggregated in any subquery within this set function. A nested set function s1 can be used within set function s0 only if s1.max_sum_func_level < s0.max_sum_func_level. Set function s1 is considered as nested for set function s0 if s1 is not calculated in any subquery within s0.

A set function that is used as a subexpression in an argument of another set function refers to the latter via the field 'in_sum_func'.

The condition imposed on the usage of set functions are checked when we traverse query subexpressions with the help of the recursive method fix_fields. When we apply this method to an object of the class Item_sum, first, on the descent, we call the method init_sum_func_check that initialize members used at checking. Then, on the ascent, we call the method check_sum_func that validates the set function usage and reports an error if it is invalid. The method check_sum_func serves to link the items for the set functions that are aggregated in the containing query blocks. Circular chains of such functions are attached to the corresponding Query_block structures through the field inner_sum_func_list.

Exploiting the fact that the members mentioned above are used in one recursive function we could have allocated them on the thread stack. Yet we don't do it now.

It is assumed that the nesting level of subqueries does not exceed 63 (valid nesting levels are stored in a 64-bit bitmap called nesting_map). The assumption is enforced in LEX::new_query().

WINDOW FUNCTIONS

Most set functions (e.g. SUM, COUNT, AVG) can also be used as window functions. In that case, notable differences compared to set functions are:

not using any Aggregator
not supporting DISTINCT
val_*() does more than returning the function's current value: it first accumulates the function's argument into the function's state. Execution (e.g. end_write_wf()) manipulates temporary tables which contain input for WFs; each input row is passed to copy_funcs() which calls the WF's val_*() to accumulate it.

Member Enumeration Documentation

◆ Sumfunctype

enum Item_sum::Sumfunctype

Enumerator
COUNT_FUNC
COUNT_DISTINCT_FUNC
SUM_FUNC
SUM_DISTINCT_FUNC
AVG_FUNC
AVG_DISTINCT_FUNC
MIN_FUNC
MAX_FUNC
STD_FUNC
VARIANCE_FUNC
SUM_BIT_FUNC
UDF_SUM_FUNC
GROUP_CONCAT_FUNC
JSON_AGG_FUNC
ROW_NUMBER_FUNC
RANK_FUNC
DENSE_RANK_FUNC
CUME_DIST_FUNC
PERCENT_RANK_FUNC
NTILE_FUNC
LEAD_LAG_FUNC
FIRST_LAST_VALUE_FUNC
NTH_VALUE_FUNC
ROLLUP_SUM_SWITCHER_FUNC
GEOMETRY_AGGREGATE_FUNC

Constructor & Destructor Documentation

◆ Item_sum() [1/6]

Item_sum::Item_sum	(	const POS &	pos,
		PT_window *	w
	)

inline

◆ Item_sum() [2/6]

Item_sum::Item_sum ( Item * a )

inline

◆ Item_sum() [3/6]

Item_sum::Item_sum	(	const POS &	pos,
		Item *	a,
		PT_window *	w
	)

inline

◆ Item_sum() [4/6]

Item_sum::Item_sum	(	const POS &	pos,
		Item *	a,
		Item *	b,
		PT_window *	w
	)

inline

◆ Item_sum() [5/6]

Item_sum::Item_sum	(	const POS &	pos,
		PT_item_list *	opt_list,
		PT_window *	w
	)

◆ Item_sum() [6/6]

Item_sum::Item_sum	(	THD *	thd,
		const Item_sum *	item
	)

Copy constructor, need to perform subqueries with temporary tables.

Constructor used in processing select with temporary tebles.

Member Function Documentation

◆ add()

virtual bool Item_sum::add ( )

pure virtual

Implemented in Item_sum_sum, Item_sum_count, Item_sum_json_array, Item_sum_json_object, Item_sum_avg, Item_sum_variance, Item_sum_hybrid, Item_sum_bit, Item_udf_sum, Item_func_group_concat, Item_non_framing_wf, Item_first_last_value, Item_nth_value, Item_rollup_sum_switcher, and Item_sum_collect.

◆ add_used_tables_for_aggr_func()

void Item_sum::add_used_tables_for_aggr_func ( )

Add used_tables information for aggregate function, based on its aggregated query block.

If the function is aggregated into its local context, it can be calculated only after evaluating the full join, thus it depends on all tables of this join. Otherwise, it depends on outer tables, even if its arguments args[] do not explicitly reference an outer table, like COUNT (*) or COUNT(123).

Window functions are always evaluated in the local scope and depend on all tables involved in the join since they cannot be evaluated until after the join is completed.

◆ aggregate_check_distinct()

bool Item_sum::aggregate_check_distinct ( uchar * )

overridevirtual

See also: Distinct_check::check_query()

Reimplemented from Item.

◆ aggregate_check_group()

bool Item_sum::aggregate_check_group ( uchar * )

overridevirtual

See also: Group_check::check_query()

Reimplemented from Item.

◆ aggregator_add()

bool Item_sum::aggregator_add ( )

inline

Called to add value to the aggregator.

◆ aggregator_clear()

void Item_sum::aggregator_clear ( )

inline

Called to cleanup the aggregator.

◆ aggregator_setup()

virtual bool Item_sum::aggregator_setup ( THD * thd )

inlinevirtual

Called to initialize the aggregator.

Reimplemented in Item_rollup_sum_switcher.

◆ check_sum_func()

bool Item_sum::check_sum_func	(	THD *	thd,
		Item **	ref
	)

Validate the semantic requirements of a set function.

Check whether the context of the set function allows it to be aggregated and, when it is an argument of another set function, directly or indirectly, the function makes sure that these two set functions are aggregated in different query blocks. If the context conditions are not met, an error is reported. If the set function is aggregated in some outer query block, it is added to the chain of items inner_sum_func_list attached to the aggregating query block.

A number of designated members of the object are used to check the conditions. They are specified in the comment before the Item_sum class declaration. Additionally a bitmap variable called allow_sum_func is employed. It is included into the LEX structure. The bitmap contains 1 at n-th position if the query block at level "n" allows a set function reference (i.e the current resolver context for the query block is either in the SELECT list or in the HAVING or ORDER BY clause).

Consider the query:

SELECT SUM(t1.b) FROM t1 GROUP BY t1.a
  HAVING t1.a IN (SELECT t2.c FROM t2 WHERE AVG(t1.b) > 20) AND
         t1.a > (SELECT MIN(t2.d) FROM t2);

when the set functions are resolved, allow_sum_func will contain:

for SUM(t1.b) - 1 at position 0 (SUM is in SELECT list)
for AVG(t1.b) - 1 at position 0 (subquery is in HAVING clause) 0 at position 1 (AVG is in WHERE clause)
for MIN(t2.d) - 1 at position 0 (subquery is in HAVING clause) 1 at position 1 (MIN is in SELECT list)

Note: This function must be called for all set functions when expressions are resolved. It must be invoked in postfix order, ie at the ascent of this traversal.

Parameters

thd	reference to the thread context info
ref	location of the pointer to this item in the containing expression

Returns: false if success, true if error

◆ check_wf_semantics1()

bool Item_sum::check_wf_semantics1	(	THD *	thd,
		Query_block *	select,
		Window_evaluation_requirements *	reqs
	)

virtual

Only relevant for aggregates qua window functions.

Checks semantics after windows have been set up and checked. Window functions have specific requirements on the window specifications. Used at resolution time.

Parameters

	thd	Current thread
	select	The current select
[out]	reqs	Holds collected requirements from this wf

Returns: true if error

Reimplemented in Item_sum_json, Item_func_group_concat, Item_row_number, Item_sum_collect, Item_sum_hybrid, Item_sum_sum, Item_sum_json_object, Item_sum_variance, Item_rank, Item_cume_dist, Item_percent_rank, Item_ntile, Item_lead_lag, Item_first_last_value, and Item_nth_value.

◆ check_wf_semantics2()

virtual bool Item_sum::check_wf_semantics2 ( Window_evaluation_requirements * reqs )

inlinevirtual

Like check_wf_semantics1.

For checks which cannot be done in resolution phase (mostly those for input parameters which can be '?' and must be >=0: value isn't known before execution phase).

Reimplemented in Item_ntile, Item_lead_lag, and Item_nth_value.

◆ clean_up_after_removal()

bool Item_sum::clean_up_after_removal ( uchar * arg )

overridevirtual

Remove the item from the list of inner aggregation functions in the Query_block it was moved to by Item_sum::check_sum_func().

This is done to undo some of the effects of Item_sum::check_sum_func() so that the item may be removed from the query.

Note: This doesn't completely undo Item_sum::check_sum_func(), as aggregation information is left untouched. This means that if this item is removed, aggr_query_block and all subquery items between aggr_query_block and this item may be left with has_aggregation() set to true, even if there are no aggregation functions. To our knowledge, this has no impact on the query result.

See also: Item_sum::check_sum_func(); remove_redundant_subquery_clauses()

If this is a window function, remove the reference from the window. This is needed when constant predicates are being removed.

See also: Item_cond::fix_fields(); Item_cond::remove_const_cond()

Reimplemented from Item.

◆ cleanup()

void Item_sum::cleanup ( )

overridevirtual

Called for every Item after use (preparation and execution).

Release all allocated resources, such as dynamic memory. Prepare for new execution by clearing cached values. Do not remove values allocated during preparation, destructor handles this.

Reimplemented from Item_result_field.

Reimplemented in Item_sum_count, Item_sum_avg, Item_sum_variance, Item_sum_hybrid, Item_sum_bit, Item_udf_sum, and Item_func_group_concat.

◆ clear()

virtual void Item_sum::clear ( )

pure virtual

◆ collect_grouped_aggregates()

bool Item_sum::collect_grouped_aggregates ( uchar * arg )

overridevirtual

Reimplemented from Item.

◆ collect_item_field_or_view_ref_processor()

bool Item_sum::collect_item_field_or_view_ref_processor ( uchar * )

overridevirtual

Collects fields and view references that have the qualifying table in the specified query block.

Don't walk below grouped aggregate functions

Reimplemented from Item.

◆ collect_scalar_subqueries()

bool Item_sum::collect_scalar_subqueries ( uchar * arg )

overridevirtual

Don't walk below grouped aggregate functions

Reimplemented from Item.

◆ create_tmp_field()

Field * Item_sum::create_tmp_field	(	bool	group,
		TABLE *	table
	)

virtual

Reimplemented in Item_sum_avg, Item_sum_variance, Item_sum_hybrid, and Item_rollup_sum_switcher.

◆ eq()

bool Item_sum::eq	(	const Item *	item,
		bool	binary_cmp
	)		const

overridevirtual

Note: Please keep in sync with Item_func::eq().

Reimplemented from Item_func.

◆ fix_after_pullout()

void Item_sum::fix_after_pullout	(	Query_block *	parent_query_block,
		Query_block *	removed_query_block
	)

overridevirtual

Fix after tables have been moved from one query_block level to the parent level, e.g by semijoin conversion.

Basically re-calculate all attributes dependent on the tables.

Parameters

parent_query_block	query_block that tables are moved to.
removed_query_block	query_block that tables are moved away from, child of parent_query_block.

Reimplemented from Item_func.

◆ fix_fields()

bool Item_sum::fix_fields	(	THD *	thd,
		Item **	ref
	)

overridevirtual

Reimplemented from Item_func.

Reimplemented in Item_sum_num, Item_sum_hybrid, Item_func_group_concat, Item_non_framing_wf, Item_ntile, Item_lead_lag, Item_first_last_value, Item_nth_value, Item_sum_json, Item_sum_bit, Item_udf_sum, and Item_sum_collect.

◆ framing()

virtual bool Item_sum::framing ( ) const

inlinevirtual

All aggregates are framing, i.e.

they work on the window's frame. If none is defined, the frame is by default the entire partition, unless ORDER BY is defined, in which case it is the set of rows from the start of the partition to and including the peer set of the current row.

Some window functions are not framing, i.e. they always work on the entire partition. For such window functions, the method is overridden to return false.

Reimplemented in Item_non_framing_wf.

◆ get_arg_ptr()

Item ** Item_sum::get_arg_ptr ( uint i )

inline

◆ has_aggregate_ref_in_group_by()

bool Item_sum::has_aggregate_ref_in_group_by ( uchar * )

overridevirtual

Check if an aggregate is referenced from within the GROUP BY clause of the query block in which it is aggregated.

Such references will be rejected.

See also: Item_ref::fix_fields()

Return values

true	if this is an aggregate which is referenced from the GROUP BY clause of the aggregating query block
false	otherwise

Reimplemented from Item.

◆ has_force_copy_fields()

bool Item_sum::has_force_copy_fields ( ) const

inline

◆ has_with_distinct()

bool Item_sum::has_with_distinct ( ) const

inline

◆ init_sum_func_check()

bool Item_sum::init_sum_func_check ( THD * thd )

Prepare an aggregate function for checking of context.

The function initializes the members of the Item_sum object. It also checks the general validity of the set function: If none of the currently active query blocks allow evaluation of set functions, an error is reported.

Note: This function must be called for all set functions when expressions are resolved. It must be invoked in prefix order, ie at the descent of this traversal.

See also: corresponding Item_sum::check_sum_func(), which should be called on ascent.

Parameters

thd	reference to the thread context info

Returns: false if success, true if error

◆ is_null()

bool Item_sum::is_null ( )

inlineoverridevirtual

The method allows to determine nullness of a complex expression without fully evaluating it, instead of calling val*() then checking null_value.

Used in Item_func_isnull/Item_func_isnotnull and Item_sum_count/Item_sum_count_distinct. Any item which can be NULL must implement this method.

Return values

false	if the expression is not NULL.
true	if the expression is NULL, or evaluation caused an error. The null_value member is set according to the return value.

Reimplemented from Item_func.

Reimplemented in Item_rollup_sum_switcher.

◆ is_rollup_sum_wrapper()

virtual bool Item_sum::is_rollup_sum_wrapper ( ) const

inlinevirtual

Overridden by Item_rollup_sum_switcher.

Reimplemented in Item_rollup_sum_switcher.

◆ itemize()

bool Item_sum::itemize	(	Parse_context *	pc,
		Item **	res
	)

overridevirtual

The same as contextualize() but with additional parameter.

This function finalize the construction of Item objects (see the Item(POS) constructor): we can access/change parser contexts from the itemize() function.

Parameters

	pc	current parse context
[out]	res	pointer to "this" or to a newly allocated replacement object to use in the Item tree instead

Return values

false	success
true	syntax/OOM/etc error

Reimplemented from Item_func.

Reimplemented in Item_udf_sum, Item_func_group_concat, and PTI_count_sym.

◆ keep_field_type()

virtual bool Item_sum::keep_field_type ( ) const

inlinevirtual

Reimplemented in Item_sum_hybrid.

◆ make_const()

void Item_sum::make_const ( )

inline

◆ make_unique()

virtual void Item_sum::make_unique ( )

inlinevirtual

Reimplemented in Item_func_group_concat.

◆ mark_as_sum_func() [1/2]

void Item_sum::mark_as_sum_func ( )

◆ mark_as_sum_func() [2/2]

void Item_sum::mark_as_sum_func ( Query_block * cur_query_block )

◆ needs_partition_cardinality()

virtual bool Item_sum::needs_partition_cardinality ( ) const

inlinevirtual

Return true if we need to make two passes over the rows in the partition - either because we need the cardinality of it (and we need to read all rows to detect the next partition), or we need to have all partition rows available to evaluate the window function for some other reason, e.g.

we may need the last row in the partition in the frame buffer to be able to evaluate LEAD.

Reimplemented in Item_cume_dist, Item_percent_rank, Item_ntile, and Item_lead_lag.

◆ no_rows_in_result()

void Item_sum::no_rows_in_result ( )

inlineoverridevirtual

Mark an aggregate as having no rows.

This function is called by the execution engine to assign 'NO ROWS FOUND' value to an aggregate item, when the underlying result set has no rows. Such value, in a general case, may be different from the default value of the item after 'clear()': e.g. a numeric item may be initialized to 0 by clear() and to NULL by no_rows_in_result().

Reimplemented from Item.

Reimplemented in Item_sum_sum, Item_sum_count, Item_sum_variance, Item_sum_hybrid, and Item_func_group_concat.

◆ not_null_tables()

table_map Item_sum::not_null_tables ( ) const

inlineoverridevirtual

Return table map of tables that can't be NULL tables (tables that are used in a context where if they would contain a NULL row generated by a LEFT or RIGHT join, the item would not be true).

This expression is used on WHERE item to determinate if a LEFT JOIN can be converted to a normal join. Generally this function should return used_tables() if the function would return null if any of the arguments are null As this is only used in the beginning of optimization, the value don't have to be updated in update_used_tables()

Reimplemented from Item_func.

◆ print()

void Item_sum::print	(	const THD *	,
		String *	str,
		enum_query_type
	)		const

overridevirtual

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;
to generate a SQL-query that looks like a prepared statement for query_rewrite
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_func.

Reimplemented in Item_udf_sum, Item_func_group_concat, and Item_rollup_sum_switcher.

◆ ram_limitation()

ulonglong Item_sum::ram_limitation ( THD * thd )

staticprotected

Calculate the affordable RAM limit for structures like TREE or Unique used in Item_sum_*.

◆ real_sum_func()

virtual enum Sumfunctype Item_sum::real_sum_func ( ) const

inlinevirtual

Reimplemented in Item_rollup_sum_switcher.

◆ replace_aggregate()

Item * Item_sum::replace_aggregate ( uchar * arg )

overridevirtual

Reimplemented from Item.

◆ reset_and_add()

bool Item_sum::reset_and_add ( )

inline

Resets the aggregate value to its default and aggregates the current value of its attribute(s).

◆ reset_field()

virtual void Item_sum::reset_field ( )

pure virtual

Implemented in Item_sum_num, Item_sum_sum, Item_sum_count, Item_sum_json, Item_sum_avg, Item_sum_variance, Item_sum_hybrid, Item_sum_bit, Item_udf_sum, Item_func_group_concat, Item_non_framing_wf, Item_first_last_value, Item_nth_value, Item_rollup_sum_switcher, and Item_sum_collect.

◆ reset_wf_state()

bool Item_sum::reset_wf_state ( uchar * arg )

overridevirtual

Reset execution state for such window function types as determined by arg.

Parameters

arg	pointing to a bool which, if true, says to reset state for framing window function, else for non-framing

Reimplemented from Item.

◆ resolve_type()

bool Item_sum::resolve_type ( THD * thd )

overridevirtual

Resolve type-related information for this item, such as result field type, maximum size, precision, signedness, character set and collation.

Also check compatibility of argument types and return error when applicable. Also adjust nullability when applicable.

Parameters

thd	thread handler

Returns: false if success, true if error

Reimplemented from Item_func.

Reimplemented in Item_sum_variance, Item_sum_bit, Item_sum_udf_float, Item_sum_udf_int, Item_sum_udf_str, Item_sum_udf_decimal, Item_rollup_sum_switcher, Item_sum_sum, Item_sum_count, Item_sum_avg, Item_row_number, Item_rank, Item_cume_dist, Item_percent_rank, Item_ntile, Item_lead_lag, Item_first_last_value, and Item_nth_value.

◆ result_item()

virtual Item * Item_sum::result_item ( Field * field )

inlinevirtual

Reimplemented in Item_sum_avg, Item_sum_variance, Item_sum_std, and Item_sum_bit.

◆ set_aggregator()

int Item_sum::set_aggregator ( Aggregator::Aggregator_type aggregator )

virtual

Reimplemented in Item_rollup_sum_switcher, and Item_sum_collect.

◆ set_arg()

Item * Item_sum::set_arg	(	THD *	thd,
		uint	i,
		Item *	new_val
	)

overridevirtual

Reimplemented from Item_func.

Reimplemented in Item_rollup_sum_switcher.

◆ set_distinct()

void Item_sum::set_distinct ( bool distinct )

inline

◆ setup()

virtual bool Item_sum::setup ( THD * )

inlinevirtual

Reimplemented in Item_func_group_concat.

◆ split_sum_func()

void Item_sum::split_sum_func	(	THD *	thd,
		Ref_item_array	ref_item_array,
		mem_root_deque< Item * > *	fields
	)

overridevirtual

See comments in Item_cmp_func::split_sum_func()

Reimplemented from Item_func.

Reimplemented in Item_sum_hybrid, Item_lead_lag, Item_first_last_value, and Item_nth_value.

◆ sum_func()

virtual enum Sumfunctype Item_sum::sum_func ( ) const

pure virtual

◆ type()

Type Item_sum::type ( ) const

inlineoverridevirtual

Reimplemented from Item_func.

◆ unsupported_as_wf()

void Item_sum::unsupported_as_wf ( )

inlineprotected

◆ unwrap_sum() [1/2]

virtual Item_sum * Item_sum::unwrap_sum ( )

inlinevirtual

Non-const version.

Reimplemented in Item_rollup_sum_switcher.

◆ unwrap_sum() [2/2]

virtual const Item_sum * Item_sum::unwrap_sum ( ) const

inlinevirtual

In case we are an Item_rollup_sum_switcher, return the underlying Item_sum, otherwise, return this.

Overridden by Item_rollup_sum_switcher.

Reimplemented in Item_rollup_sum_switcher.

◆ update_after_wf_arguments_changed()

virtual void Item_sum::update_after_wf_arguments_changed ( THD * )

inlinevirtual

Signal to the function that its arguments may have changed, and that any internal caches etc.

based on those arguments must be updated accordingly.

This is used by the hypergraph optimizer when it rewrites arguments to window functions to take into account that they have been materialized into temporary tables, or that they should read their values from the framebuffer.

Reimplemented in Item_sum_hybrid, Item_rank, Item_lead_lag, Item_first_last_value, and Item_nth_value.

◆ update_field()

virtual void Item_sum::update_field ( )

pure virtual

Implemented in Item_sum_sum, Item_sum_count, Item_sum_json, Item_sum_avg, Item_sum_variance, Item_sum_hybrid, Item_sum_bit, Item_udf_sum, Item_func_group_concat, Item_non_framing_wf, Item_first_last_value, Item_nth_value, Item_rollup_sum_switcher, and Item_sum_collect.

◆ update_used_tables()

void Item_sum::update_used_tables ( )

overridevirtual

Updates used tables, not null tables information and accumulates properties up the item tree, cf.

used_tables_cache, not_null_tables_cache and m_accum_properties.

TODO(sgunders): Consider just removing these caches; it causes a lot of bugs (cache invalidation is known to be a complex problem), and the performance benefits are dubious.

Reimplemented from Item_func.

◆ used_tables()

table_map Item_sum::used_tables ( ) const

inlineoverridevirtual

Reimplemented from Item_func.

Reimplemented in Item_rollup_sum_switcher.

◆ uses_only_one_row()

virtual bool Item_sum::uses_only_one_row ( ) const

inlinevirtual

Only for framing window functions.

True if this function only needs to read one row per frame.

Reimplemented in Item_sum_hybrid, Item_first_last_value, and Item_nth_value.

◆ wf_common_init()

bool Item_sum::wf_common_init ( )

Common initial actions for window functions.

For non-buffered processing ("on-the-fly"), check partition change and possible reset partition state. In this case return false. For buffered processing, if windowing state m_do_copy_null is true, set null_value to is_nullable() and return true.

Returns: true if case two above holds, else false

◆ window() [1/2]

Window * Item_sum::window ( )

inline

◆ window() [2/2]

const Window * Item_sum::window ( ) const

inline

Friends And Related Function Documentation

◆ Aggregator_distinct

friend class Aggregator_distinct

friend

◆ Aggregator_simple

friend class Aggregator_simple

friend

Member Data Documentation

◆ aggr

Aggregator* Item_sum::aggr {nullptr}

protected

Aggregator class instance.

Not set initially. Allocated only after it is determined if the incoming data are already distinct.

◆ aggr_query_block

Query_block* Item_sum::aggr_query_block

For a group aggregate, query block where function is aggregated.

For a window function, nullptr, as such function is always aggregated in base_query_block, as it mustn't contain any outer reference.

◆ allow_group_via_temp_table

bool Item_sum::allow_group_via_temp_table

If incremental update of fields is supported.

◆ base_query_block

Query_block* Item_sum::base_query_block

query block where function is placed

◆ force_copy_fields

bool Item_sum::force_copy_fields {false}

private

Used in making ROLLUP.

Set for the ROLLUP copies of the original Item_sum and passed to create_tmp_field() to cause it to work over the temp table buffer that is referenced by Item_result_field::result_field.

◆ forced_const

bool Item_sum::forced_const {false}

protected

True means that this field has been evaluated during optimization.

When set, used_tables() returns zero and const_item() returns true. The value must be reset to false after execution.

◆ in_sum_func

Item_sum* Item_sum::in_sum_func

the containing set function if any

◆ m_null_executed

bool Item_sum::m_null_executed {false}

protected

true if the function is determined to be NULL at start of execution

◆ m_null_resolved

bool Item_sum::m_null_resolved {false}

protected

true if the function is resolved to be always NULL

◆ m_window

PT_window* Item_sum::m_window {nullptr}

protected

If sum is a window function, this field contains the window.

◆ m_window_resolved

bool Item_sum::m_window_resolved {false}

protected

True if we have already resolved this window functions window reference.

Used in execution of prepared statement to avoid re-resolve.

◆ max_aggr_level

int8 Item_sum::max_aggr_level

max level of unbound column references

◆ max_sum_func_level

int8 Item_sum::max_sum_func_level

max level of aggregation for contained functions

◆ next_sum

Item_sum* Item_sum::next_sum {nullptr}

next in the circular chain of registered objects

◆ referenced_by

Item** Item_sum::referenced_by[2]

For a group aggregate which is aggregated into an outer query block; none, or just the first or both cells may be non-zero.

Note: most member variables below serve only for grouped aggregate functions. They are filled with references to the group aggregate (for example if it is the argument of a function; it is then a pointer to that function's args[i] pointer).

◆ save_deny_window_func

nesting_map Item_sum::save_deny_window_func

WFs are forbidden when resolving Item_sum; this member is used to restore WF allowance status afterwards.

◆ with_distinct

bool Item_sum::with_distinct {false}

private

Indicates how the aggregate function was specified by the parser : true if it was written as AGGREGATE(DISTINCT), false if it was AGGREGATE()

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

sql/item_sum.h
sql/item_sum.cc

Classes

Public Types

Public Member Functions

Public Attributes

Protected Member Functions

Static Protected Member Functions

Protected Attributes

Private Attributes

Friends

Additional Inherited Members

Detailed Description

Member Enumeration Documentation

◆ Sumfunctype

Constructor & Destructor Documentation

◆ Item_sum() [1/6]

◆ Item_sum() [2/6]

◆ Item_sum() [3/6]

◆ Item_sum() [4/6]

◆ Item_sum() [5/6]

◆ Item_sum() [6/6]

Member Function Documentation

◆ add()

◆ add_used_tables_for_aggr_func()

◆ aggregate_check_distinct()

◆ aggregate_check_group()

◆ aggregator_add()

◆ aggregator_clear()

◆ aggregator_setup()

◆ check_sum_func()

◆ check_wf_semantics1()

◆ check_wf_semantics2()

◆ clean_up_after_removal()

◆ cleanup()

◆ clear()

◆ collect_grouped_aggregates()

◆ collect_item_field_or_view_ref_processor()

◆ collect_scalar_subqueries()

◆ create_tmp_field()

◆ eq()

◆ fix_after_pullout()

◆ fix_fields()

◆ framing()

◆ get_arg_ptr()

◆ has_aggregate_ref_in_group_by()

◆ has_force_copy_fields()

◆ has_with_distinct()

◆ init_sum_func_check()

◆ is_null()

◆ is_rollup_sum_wrapper()

◆ itemize()

◆ keep_field_type()

◆ make_const()

◆ make_unique()

◆ mark_as_sum_func() [1/2]

◆ mark_as_sum_func() [2/2]

◆ needs_partition_cardinality()

◆ no_rows_in_result()

◆ not_null_tables()

◆ print()

◆ ram_limitation()

◆ real_sum_func()

◆ replace_aggregate()

◆ reset_and_add()

◆ reset_field()

◆ reset_wf_state()

◆ resolve_type()

◆ result_item()

◆ set_aggregator()

◆ set_arg()

◆ set_distinct()

◆ setup()

◆ split_sum_func()

◆ sum_func()

◆ type()

◆ unsupported_as_wf()

◆ unwrap_sum() [1/2]

◆ unwrap_sum() [2/2]

◆ update_after_wf_arguments_changed()

◆ update_field()

◆ update_used_tables()