Group_check Class Reference

Checks for queries which have GROUP BY or aggregate functions. More...

#include <aggregate_check.h>

Inheritance diagram for Group_check:

Public Member Functions
	Group_check (Query_block *select_arg, MEM_ROOT *root)
	~Group_check ()
	Group_check (const Group_check &)=delete
Group_check &	operator= (const Group_check &)=delete
bool	check_query (THD *thd)
	Rejects the query if it does aggregation or grouping, and expressions in its SELECT list, ORDER BY clause, HAVING condition, or window functions may vary inside a group (are not "group-invariant"). More...
void	to_opt_trace (THD *thd)
	Writes "check information" to the optimizer trace. More...

Private Types
enum	enum_ident_check { CHECK_GROUP , CHECK_STRONG_SIDE_COLUMN , CHECK_COLUMN }
	Enum for argument of do_ident_check() More...

Private Member Functions
bool	is_fd_on_source (Item *item)
	Tells if 'item' is functionally dependent ("FD") on source columns. More...
bool	is_child () const
	Group_check (Query_block *select_arg, MEM_ROOT *root, Table_ref *table_arg)
	Private ctor, for a Group_check to build a child Group_check. More...
bool	check_expression (THD *thd, Item *expr, bool in_select_list)
	Validates one expression (this forms one step of check_query()). More...
bool	local_column (Item *item) const
	Shortcut for common use of Item::local_column() More...
void	add_to_fd (Item *item, bool local_column, bool add_to_mat_table=true)
void	add_to_fd (table_map m)
void	add_to_source_of_mat_table (Item_field *item_field, Table_ref *tl)
	If we just added a column of a materialized table to 'fd', we record this fact in a new Group_check (mat_gc) for the query expression underlying that table. More...
bool	is_in_fd (Item *item)
	is_in_fd() is low-level compared to is_fd_on_source(). More...
bool	is_in_fd_of_underlying (Item_ident *item)
	See if we can derive a FD from a column which has an underlying expression. More...
Item *	get_fd_equal (Item *item)
void	analyze_conjunct (Item *cond, Item *conjunct, table_map weak_tables, bool weak_side_upwards)
	Searches for equality-based functional dependences in an AND-ed part of a condition (a conjunct). More...
void	analyze_scalar_eq (Item *cond, Item *left_item, Item *right_item, table_map weak_tables, bool weak_side_upwards)
	Helper function. More...
void	find_fd_in_cond (Item *cond, table_map weak_tables, bool weak_side_upwards)
	Searches for equality-based functional dependencies in a condition. More...
void	find_fd_in_joined_table (mem_root_deque< Table_ref * > *join_list)
	Searches for equality-based functional dependencies in the condition of a join nest, and recursively in all contained join nests. More...
void	to_opt_trace2 (Opt_trace_context *ctx, Opt_trace_object *parent)
	Utility function for to_opt_trace(), as we need recursion in children Group_checks. More...
void	find_group_in_fd (Item *item)
	This function must be called every time we discover an item which is FD on source columns, or add a bit to whole_tables_fd; it maintains group_in_fd. More...
Item *	select_expression (uint idx)
bool	do_ident_check (Item_ident *i, table_map tm, enum enum_ident_check type)
	Does one low-level check on one Item_ident. More...

Private Attributes
Query_block *const	select
	Query block which we are validating. More...
bool	search_in_underlying
	"Underlying" == expressions which are underlying in an identifier. More...
bool	non_null_in_source
	This member is readable only if this is a child Group_check. More...
Table_ref *const	table
	The Group_check employed to validate one query block, the one on which check_query() runs, is named the "master". More...
ulonglong	group_in_fd
	Bit N is set if the N-th expression of GROUP BY is functionally dependent on source columns. More...
MEM_ROOT *const	m_root
	Memory for allocations (like of 'fd') More...
Mem_root_array< Item_ident * >	fd
	Columns which are local to 'select' and functionally dependent on an initial set of "source" columns defined like this: More...
table_map	whole_tables_fd
	Map of tables for which all columns can be considered part of 'fd'. More...
table_map	recheck_nullable_keys
	Map of tables for which we discovered known-not-nullable columns. More...
Mem_root_array< Group_check * >	mat_tables
	Children Group_checks of 'this'. More...
Item_ident *	failed_ident
	Identifier which triggered an error. More...

Friends
bool	Item_ident::aggregate_check_group (uchar *arg)
	Just because we need to go through Item::walk() to reach all items to validate, some work must be delegated to "Item processors" (members of Item); this work conceptually belongs to Group_check, and needs privileged access to it. More...
bool	Item_sum::aggregate_check_group (uchar *arg)
bool	Item_func_any_value::aggregate_check_group (uchar *arg)
bool	Item_ident::is_strong_side_column_not_in_fd (uchar *arg)
bool	Item_ident::is_column_not_in_fd (uchar *arg)
bool	Item_func_grouping::aggregate_check_group (uchar *arg)

Additional Inherited Members
Protected Member Functions inherited from Item_tree_walker
	Item_tree_walker ()
	~Item_tree_walker ()
	Item_tree_walker (const Item_tree_walker &)=delete
Item_tree_walker &	operator= (const Item_tree_walker &)=delete
void	stop_at (const Item *i)
	Stops walking children of this item. More...
bool	is_stopped (const Item *i)

Detailed Description

Checks for queries which have GROUP BY or aggregate functions.

Member Enumeration Documentation

enum_ident_check

enum Group_check::enum_ident_check

private

Enum for argument of do_ident_check()

Enumerator
CHECK_GROUP
CHECK_STRONG_SIDE_COLUMN
CHECK_COLUMN

Constructor & Destructor Documentation

Group_check() [1/3]

Group_check::Group_check ( Query_block *  select_arg, MEM_ROOT *  root  )

inline

~Group_check()

Group_check::~Group_check ( )

inline

Group_check() [2/3]

Group_check::Group_check ( const Group_check &  )

delete

Group_check() [3/3]

Group_check::Group_check ( Query_block *  select_arg, MEM_ROOT *  root, Table_ref *  table_arg  )

inlineprivate

Private ctor, for a Group_check to build a child Group_check.

Member Function Documentation

add_to_fd()

void Group_check::add_to_fd ( table_map  m )

inlineprivate

is_child()

bool Group_check::is_child ( ) const

inlineprivate

local_column()

bool Group_check::local_column ( Item *  item ) const

inlineprivate

Shortcut for common use of Item::local_column()

operator=()

Group_check & Group_check::operator= ( const Group_check &  )

delete

Friends And Related Function Documentation

Item_func_any_value::aggregate_check_group

bool Item_func_any_value::aggregate_check_group ( uchar *  arg )

friend

Item_func_grouping::aggregate_check_group

bool Item_func_grouping::aggregate_check_group ( uchar *  arg )

friend

Item_ident::aggregate_check_group

bool Item_ident::aggregate_check_group ( uchar *  arg )

friend

Just because we need to go through Item::walk() to reach all items to validate, some work must be delegated to "Item processors" (members of Item); this work conceptually belongs to Group_check, and needs privileged access to it.

Item_ident::is_column_not_in_fd

bool Item_ident::is_column_not_in_fd ( uchar *  arg )

friend

Item_ident::is_strong_side_column_not_in_fd

bool Item_ident::is_strong_side_column_not_in_fd ( uchar *  arg )

friend

Item_sum::aggregate_check_group

bool Item_sum::aggregate_check_group ( uchar *  arg )

friend

Member Data Documentation

failed_ident

Item_ident* Group_check::failed_ident

private

Identifier which triggered an error.

fd

Mem_root_array<Item_ident *> Group_check::fd

private

Columns which are local to 'select' and functionally dependent on an initial set of "source" columns defined like this:

• if !is_child(), the GROUP BY columns
• if is_child(), columns of the result of the query expression under 'table' which are themselves part of 'fd' of the parent Group_check.

group_in_fd

ulonglong Group_check::group_in_fd

private

Bit N is set if the N-th expression of GROUP BY is functionally dependent on source columns.

It serves to find FDs in the query expression of a materialized table having GROUP BY. For a non-child Group-check, all bits are turned on from the start. Currently limited to 64 bits => max 64 GROUP expressions; should probably be MY_BITMAP.

m_root

MEM_ROOT* const Group_check::m_root

private

Memory for allocations (like of 'fd')

mat_tables

Mem_root_array<Group_check *> Group_check::mat_tables

private

Children Group_checks of 'this'.

non_null_in_source

bool Group_check::non_null_in_source

private

This member is readable only if this is a child Group_check.

Is true if one expression of the SELECT list of this->select is non-nullable.

recheck_nullable_keys

table_map Group_check::recheck_nullable_keys

private

Map of tables for which we discovered known-not-nullable columns.

search_in_underlying

bool Group_check::search_in_underlying

private

"Underlying" == expressions which are underlying in an identifier.

The identifier can be a column of a view or derived table, both merged or materialized, or a generated column: all of those have an underlying expression. "Materialized table (mat table)" == view or derived table, materialized. If this is true, is_in_fd() will look for FDs in underlying expressions of columns.

select

Query_block* const Group_check::select

private

Query block which we are validating.

table

Table_ref* const Group_check::table

private

The Group_check employed to validate one query block, the one on which check_query() runs, is named the "master".

If the query block references a materialized table, the master may create a child Group_check, whose job is to discover FDs in the query expression of the mat table (with the ultimate goal of deducing from them some FDs in the mat table and thus in the parent Group_check). A child may have children itself. If this Group_check is a child, 'table' points to the materialized table, otherwise it is NULL.

whole_tables_fd

table_map Group_check::whole_tables_fd

private

Map of tables for which all columns can be considered part of 'fd'.

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

• sql/aggregate_check.h
• sql/aggregate_check.cc