HashJoinCondition Class Reference

A class that represents a join condition in a hash join. More...

#include <item_cmpfunc.h>

Public Member Functions
	HashJoinCondition (Item_eq_base *join_condition, MEM_ROOT *mem_root)
Item_eq_base *	join_condition () const
Item *	left_extractor () const
Item *	right_extractor () const
bool	left_uses_any_table (table_map tables) const
bool	right_uses_any_table (table_map tables) const
size_t	max_character_length () const
bool	store_full_sort_key () const
bool	null_equals_null () const
	Returns true if this join condition evaluates to TRUE if both operands are NULL. More...

Private Attributes
Item_eq_base *	m_join_condition
Item *	m_left_extractor
Item *	m_right_extractor
const table_map	m_left_used_tables
const table_map	m_right_used_tables
const size_t	m_max_character_length {0}
bool	m_store_full_sort_key
bool	m_null_equals_null

Detailed Description

A class that represents a join condition in a hash join.

The class holds an equality condition, as well as a pre-calculated bitmap of the used tables (Item::used_tables()) for each side of the condition.

The class also contains one Item for each side of the condition. In most cases, the Item is only a pointer to the left/right Item of the join condition. But for certain data types (DECIMAL, DOUBLE(M, N), FLOAT(M, N)), the Item might be a typecast. Either way, the caller should use these Items when i.e. reading the values from the join condition, so that the values are read in the right data type context. See the comments for Item_eq_base::create_cast_if_needed for more details around this.

Constructor & Destructor Documentation

HashJoinCondition()

HashJoinCondition::HashJoinCondition	(	Item_eq_base *	join_condition,
		MEM_ROOT *	mem_root
	)

Member Function Documentation

join_condition()

Item_eq_base * HashJoinCondition::join_condition ( ) const

inline

left_extractor()

Item * HashJoinCondition::left_extractor ( ) const

inline

left_uses_any_table()

bool HashJoinCondition::left_uses_any_table ( table_map  tables ) const

inline

max_character_length()

size_t HashJoinCondition::max_character_length ( ) const

inline

null_equals_null()

bool HashJoinCondition::null_equals_null ( ) const

inline

Returns true if this join condition evaluates to TRUE if both operands are NULL.

right_extractor()

Item * HashJoinCondition::right_extractor ( ) const

inline

right_uses_any_table()

bool HashJoinCondition::right_uses_any_table ( table_map  tables ) const

inline

store_full_sort_key()

bool HashJoinCondition::store_full_sort_key ( ) const

inline

Member Data Documentation

m_join_condition

Item_eq_base* HashJoinCondition::m_join_condition

private

m_left_extractor

Item* HashJoinCondition::m_left_extractor

private

m_left_used_tables

const table_map HashJoinCondition::m_left_used_tables

private

m_max_character_length

const size_t HashJoinCondition::m_max_character_length {0}

private

m_null_equals_null

bool HashJoinCondition::m_null_equals_null

private

m_right_extractor

Item* HashJoinCondition::m_right_extractor

private

m_right_used_tables

const table_map HashJoinCondition::m_right_used_tables

private

m_store_full_sort_key

bool HashJoinCondition::m_store_full_sort_key

private

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

• sql/item_cmpfunc.h
• sql/item_cmpfunc.cc