#include "sql/opt_hints.h"
#include <assert.h>
#include <stdio.h>
#include <string.h>
#include <algorithm>
#include "m_ctype.h"
#include "my_table_map.h"
#include "mysql/udf_registration_types.h"
#include "mysqld_error.h"
#include "sql/derror.h"
#include "sql/error_handler.h"
#include "sql/item.h"
#include "sql/item_subselect.h"
#include "sql/key.h"
#include "sql/mysqld.h"
#include "sql/nested_join.h"
#include "sql/parse_tree_hints.h"
#include "sql/set_var.h"
#include "sql/sql_class.h"
#include "sql/sql_const.h"
#include "sql/sql_error.h"
#include "sql/sql_optimizer.h"
#include "sql/sql_select.h"
#include "sql/table.h"

Classes
class	Join_order_hint_handler
	Auxiliary class is used to save/restore table dependencies. More...

Functions
int	cmp_lex_string (const LEX_CSTRING &s, const LEX_CSTRING &t, const CHARSET_INFO *cs)

static void	print_join_order_warn (THD thd, opt_hints_enum type, const Hint_param_table hint_table)
	Print warning about unresolved table for join order hints. More...

static bool	compare_table_name (const Hint_param_table hint_table, const Table_ref table)
	Function compares hint table name and Table_ref table name. More...

static table_map	get_other_dep (opt_hints_enum type, table_map hint_tab_map, table_map table_map)
	Function returns dependencies used for updating table dependencies depending on hint type. More...

static void	update_nested_join_deps (JOIN join, const JOIN_TAB hint_tab, table_map hint_tab_map)
	Function updates dependencies for nested joins. More...

static bool	set_join_hint_deps (JOIN join, const Hint_param_table_list hint_table_list, opt_hints_enum type)
	Function resolves hint tables, checks and sets table dependencies according to the hint. More...

bool	is_compound_hint (opt_hints_enum type_arg)

static void	print_hint_from_var (const THD thd, String str, set_var *var)
	Function prints hint using the info from set_var variable. More...

static void	print_hint_specified (String str, const std::string &sys_var_name, Item sys_var_value)
	Function prints hint as it is specified. More...

static bool	get_hint_state (Opt_hints hint, Opt_hints parent_hint, opt_hints_enum type_arg, bool *ret_val)
	Function returns hint value depending on the specified hint level. More...

bool	hint_key_state (const THD thd, const Table_ref table, uint keyno, opt_hints_enum type_arg, uint optimizer_switch)
	Returns key hint value if hint is specified, returns optimizer switch value if hint is not specified. More...

bool	hint_table_state (const THD thd, const Table_ref table_list, opt_hints_enum type_arg, uint optimizer_switch)
	Returns table hint value if hint is specified, returns optimizer switch value if hint is not specified. More...

void	append_table_name (const THD thd, String str, const LEX_CSTRING qb_name, const LEX_CSTRING table_name)
	Append table and query block name. More...

bool	compound_hint_key_enabled (const TABLE *table, uint keyno, opt_hints_enum type_arg)
	Returns true if compound hint state is on with or without specified keys, otherwise returns false. More...

bool	idx_merge_hint_state (THD thd, const TABLE table, bool *use_cheapest_index_merge)
	Returns true if index merge hint state is on otherwise returns false. More...

Variables
struct st_opt_hint_info	opt_hint_info []
	Information about hints. More...

const LEX_CSTRING	sys_qb_prefix = {"select#", 7}
	Prefix for system generated query block name. More...

Function Documentation

◆ append_table_name()

void append_table_name	(	const THD *	thd,
		String *	str,
		const LEX_CSTRING *	qb_name,
		const LEX_CSTRING *	table_name
	)

Append table and query block name.

Parameters

thd	pointer to THD object
str	pointer to String object
qb_name	pointer to query block name, may be null
table_name	pointer to table name

◆ cmp_lex_string()

int cmp_lex_string	(	const LEX_CSTRING &	s,
		const LEX_CSTRING &	t,
		const CHARSET_INFO *	cs
	)

◆ compare_table_name()

static bool compare_table_name	(	const Hint_param_table *	hint_table,
		const Table_ref *	table
	)

static

Function compares hint table name and Table_ref table name.

Query block name is taken into account.

Parameters

hint_table	hint table name
table	pointer to Table_ref object

Returns: false if table names are equal, true otherwise.

◆ compound_hint_key_enabled()

bool compound_hint_key_enabled	(	const TABLE *	table,
		uint	keyno,
		opt_hints_enum	type_arg
	)

Returns true if compound hint state is on with or without specified keys, otherwise returns false.

If compound hint state is on and hint is specified without indexes, function returns 'true' for any 'keyno' argument. If hint specified with indexes, function returns true only for appropriate 'keyno' index.

Parameters

table	Pointer to TABLE object
keyno	Key number
type_arg	Hint type

Returns: true if compound hint state is on with or without specified keys, otherwise returns false.

◆ get_hint_state()

static bool get_hint_state	(	Opt_hints *	hint,
		Opt_hints *	parent_hint,
		opt_hints_enum	type_arg,
		bool *	ret_val
	)

static

Function returns hint value depending on the specified hint level.

If hint is specified on current level, current level hint value is returned, otherwise parent level hint is checked.

Parameters

	hint	Pointer to the hint object
	parent_hint	Pointer to the parent hint object, should never be NULL
	type_arg	hint type
[out]	ret_val	hint value depending on what hint level is used

Returns: true if hint is specified, false otherwise

◆ get_other_dep()

static table_map get_other_dep	(	opt_hints_enum	type,
		table_map	hint_tab_map,
		table_map	table_map
	)

static

Function returns dependencies used for updating table dependencies depending on hint type.

Parameters

type	hint type
hint_tab_map	hint table map
table_map	table map

Returns: table dependencies.

◆ hint_key_state()

bool hint_key_state	(	const THD *	thd,
		const Table_ref *	table,
		uint	keyno,
		opt_hints_enum	type_arg,
		uint	optimizer_switch
	)

Returns key hint value if hint is specified, returns optimizer switch value if hint is not specified.

Parameters

thd	Pointer to THD object
table	Pointer to Table_ref object
keyno	Key number
type_arg	Hint type
optimizer_switch	Optimizer switch flag

Returns: key hint value if hint is specified, otherwise optimizer switch value.

◆ hint_table_state()

bool hint_table_state	(	const THD *	thd,
		const Table_ref *	table,
		opt_hints_enum	type_arg,
		uint	optimizer_switch
	)

Returns table hint value if hint is specified, returns optimizer switch value if hint is not specified.

Parameters

thd	Pointer to THD object
table	Pointer to Table_ref object
type_arg	Hint type
optimizer_switch	Optimizer switch flag

Returns: table hint value if hint is specified, otherwise optimizer switch value.

◆ idx_merge_hint_state()

bool idx_merge_hint_state	(	THD *	thd,
		const TABLE *	table,
		bool *	use_cheapest_index_merge
	)

Returns true if index merge hint state is on otherwise returns false.

Parameters

thd	Thread handler
table	Pointer to TABLE object
use_cheapest_index_merge	IN/OUT Returns true if INDEX_MERGE hint is used without any specified key.

Returns: true if index merge hint state is on otherwise returns false.

◆ is_compound_hint()

bool is_compound_hint ( opt_hints_enum type_arg )

◆ print_hint_from_var()

static void print_hint_from_var	(	const THD *	thd,
		String *	str,
		set_var *	var
	)

static

Function prints hint using the info from set_var variable.

Parameters

thd	Thread handle
str	Pointer to string object
var	Pointer to set_var object

◆ print_hint_specified()

static void print_hint_specified	(	String *	str,
		const std::string &	sys_var_name,
		Item *	sys_var_value
	)

static

Function prints hint as it is specified.

Parameters

str	Pointer to string object
sys_var_name	Variable name
sys_var_value	Variable value

◆ print_join_order_warn()

static void print_join_order_warn	(	THD *	thd,
		opt_hints_enum	type,
		const Hint_param_table *	hint_table
	)

static

Print warning about unresolved table for join order hints.

Parameters

thd	pointer to THD object
type	hint type
hint_table	table name

◆ set_join_hint_deps()

static bool set_join_hint_deps	(	JOIN *	join,
		const Hint_param_table_list *	hint_table_list,
		opt_hints_enum	type
	)

static

Function resolves hint tables, checks and sets table dependencies according to the hint.

If the hint is ignored due to circular table dependencies, original dependencies are restored.

Parameters

join	pointer to JOIN object
hint_table_list	hint table list
type	hint type

Returns: false if hint is applied, true otherwise.

◆ update_nested_join_deps()

static void update_nested_join_deps	(	JOIN *	join,
		const JOIN_TAB *	hint_tab,
		table_map	hint_tab_map
	)

static

Function updates dependencies for nested joins.

If table specified in the hint belongs to nested join, we need to update dependencies of all tables of the nested join with the same dependency as for the hint table. It is also necessary to update all tables of the nested joins this table is part of.

Parameters

join	pointer to JOIN object
hint_tab	pointer to JOIN_TAB object
hint_tab_map	map of the tables, specified in the hint

Variable Documentation

◆ opt_hint_info

struct st_opt_hint_info opt_hint_info[]

Initial value:

= {
    {"BKA", true, true, false},
    {"BNL", true, true, false},
    {"ICP", true, true, false},
    {"MRR", true, true, false},
    {"NO_RANGE_OPTIMIZATION", true, true, false},
    {"MAX_EXECUTION_TIME", false, false, false},
    {"QB_NAME", false, false, false},
    {"SEMIJOIN", false, false, false},
    {"SUBQUERY", false, false, false},
    {"MERGE", true, true, false},
    {"JOIN_PREFIX", false, false, true},
    {"JOIN_SUFFIX", false, false, true},
    {"JOIN_ORDER", false, false, true},
    {"JOIN_FIXED_ORDER", false, true, false},
    {"INDEX_MERGE", false, false, false},
    {"RESOURCE_GROUP", false, false, false},
    {"SKIP_SCAN", false, false, false},
    {"HASH_JOIN", true, true, false},
    {"INDEX", false, false, false},
    {"JOIN_INDEX", false, false, false},
    {"GROUP_INDEX", false, false, false},
    {"ORDER_INDEX", false, false, false},
    {"DERIVED_CONDITION_PUSHDOWN", true, true, false},
    {nullptr, false, false, false}}

Information about hints.

Should be synchronized with opt_hints_enum enum.

Note: Hint name depends on hint state. 'NO_' prefix is added if appropriate hint state bit(see Opt_hints_map::hints) is not set. Depending on 'switch_state_arg' argument in 'parse tree object' constructors(see parse_tree_hints.[h,cc]) implementor can control wishful form of the hint name.

◆ sys_qb_prefix

const LEX_CSTRING sys_qb_prefix = {"select#", 7}

Prefix for system generated query block name.

Used in information warning in EXPLAIN oputput.

Classes

Functions

Variables

Function Documentation

◆ append_table_name()

◆ cmp_lex_string()

◆ compare_table_name()

◆ compound_hint_key_enabled()

◆ get_hint_state()

◆ get_other_dep()

◆ hint_key_state()

◆ hint_table_state()

◆ idx_merge_hint_state()

◆ is_compound_hint()

◆ print_hint_from_var()

◆ print_hint_specified()

◆ print_join_order_warn()

◆ set_join_hint_deps()

◆ update_nested_join_deps()

Variable Documentation

◆ opt_hint_info

◆ sys_qb_prefix