subselect_indexsubquery_engine Class Reference

A subquery execution engine that evaluates the subquery by doing index lookups in a single table's index. More...

#include <item_subselect.h>

Inheritance diagram for subselect_indexsubquery_engine:

Public Types
enum	enum_engine_type { INDEXSUBQUERY_ENGINE , HASH_SJ_ENGINE }

Public Member Functions
	subselect_indexsubquery_engine (TABLE *table, Table_ref *table_ref, const Index_lookup &ref, enum join_type join_type, Item_in_subselect *subs, Item *where, Item *having)
virtual	~subselect_indexsubquery_engine ()=default
virtual bool	exec (THD *thd)
virtual void	print (const THD *thd, String *str, enum_query_type query_type)
virtual enum_engine_type	engine_type () const
virtual void	cleanup ()
virtual void	create_iterators (THD *)

Protected Attributes
Query_result_union *	result = nullptr
TABLE *	table {nullptr}
	Table which is read, using one of eq_ref, ref, ref_or_null. More...
Table_ref *	table_ref {nullptr}
Index_lookup	ref
join_type	type {JT_UNKNOWN}
Item *	m_cond
	The WHERE condition of the subquery. More...
ulonglong	m_hash
	Hash value calculated by RefIterator, when needed. More...
Item *	m_having
Item_in_subselect *	item

Detailed Description

A subquery execution engine that evaluates the subquery by doing index lookups in a single table's index.

This engine is used to resolve subqueries in forms

outer_expr IN (SELECT tbl.key FROM tbl WHERE subq_where)

or, row-based:

(oe1, .. oeN) IN (SELECT key_part1, ... key_partK FROM tbl WHERE subqwhere)

i.e. the subquery is a single table SELECT without GROUP BY, aggregate functions, etc.

Member Enumeration Documentation

enum_engine_type

enum subselect_indexsubquery_engine::enum_engine_type

Enumerator
INDEXSUBQUERY_ENGINE
HASH_SJ_ENGINE

Constructor & Destructor Documentation

subselect_indexsubquery_engine()

subselect_indexsubquery_engine::subselect_indexsubquery_engine ( TABLE *  table, Table_ref *  table_ref, const Index_lookup &  ref, enum join_type  join_type, Item_in_subselect *  subs, Item *  where, Item *  having  )

inline

~subselect_indexsubquery_engine()

virtual subselect_indexsubquery_engine::~subselect_indexsubquery_engine ( )

virtualdefault

Member Function Documentation

cleanup()

virtual void subselect_indexsubquery_engine::cleanup ( )

inlinevirtual

Reimplemented in subselect_hash_sj_engine.

create_iterators()

virtual void subselect_indexsubquery_engine::create_iterators ( THD *  )

inlinevirtual

Reimplemented in subselect_hash_sj_engine.

engine_type()

virtual enum_engine_type subselect_indexsubquery_engine::engine_type ( ) const

inlinevirtual

Reimplemented in subselect_hash_sj_engine.

exec()

bool subselect_indexsubquery_engine::exec ( THD *  thd )

virtual

Reimplemented in subselect_hash_sj_engine.

print()

void subselect_indexsubquery_engine::print ( const THD *  thd, String *  str, enum_query_type  query_type  )

virtual

Reimplemented in subselect_hash_sj_engine.

Member Data Documentation

item

Item_in_subselect* subselect_indexsubquery_engine::item

protected

m_cond

Item* subselect_indexsubquery_engine::m_cond

protected

The WHERE condition of the subquery.

m_hash

ulonglong subselect_indexsubquery_engine::m_hash

protected

Hash value calculated by RefIterator, when needed.

m_having

Item* subselect_indexsubquery_engine::m_having

protected

ref

Index_lookup subselect_indexsubquery_engine::ref

protected

result

Query_result_union* subselect_indexsubquery_engine::result = nullptr

protected

table

TABLE* subselect_indexsubquery_engine::table {nullptr}

protected

Table which is read, using one of eq_ref, ref, ref_or_null.

table_ref

Table_ref* subselect_indexsubquery_engine::table_ref {nullptr}

protected

type

join_type subselect_indexsubquery_engine::type {JT_UNKNOWN}

protected

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

• sql/item_subselect.h
• sql/item_subselect.cc