Query_result_union Class Reference

#include <sql_union.h>

Inheritance diagram for Query_result_union:

Public Member Functions
	Query_result_union ()
bool	prepare (THD *thd, const mem_root_deque< Item * > &list, Query_expression *u) override
	Perform preparation specific to the query expression or DML statement. More...
virtual bool	postponed_prepare (THD *thd, const mem_root_deque< Item * > &types)
	Do prepare() if preparation has been postponed until column type information is computed (used by Query_result_union_direct). More...
bool	send_data (THD *thd, const mem_root_deque< Item * > &items) override
bool	send_eof (THD *thd) override
virtual bool	flush ()
void	cleanup () override
	Cleanup after this execution. More...
bool	reset () override
	Reset and empty the temporary table that stores the materialized query result. More...
bool	create_result_table (THD *thd, const mem_root_deque< Item * > &column_types, bool is_distinct, ulonglong options, const char *alias, bool create_table, Query_term_set_op *op=nullptr)
	Create a temporary table to store the result of a query expression (used, among others, when materializing a UNION DISTINCT). More...
uint	get_hidden_field_count () const
bool	skip_create_table () const
void	set_limit (ha_rows limit_rows) override
	Set an effective LIMIT for the number of rows coming out of a materialized temporary table used for implementing INTERSECT or EXCEPT: informs TableScanIterator::TableScanIterator how many rows to read from the materialized table. More...
Public Member Functions inherited from Query_result_interceptor
	Query_result_interceptor ()
uint	field_count (const mem_root_deque< Item * > &) const override
bool	send_result_set_metadata (THD *, const mem_root_deque< Item * > &, uint) override
Public Member Functions inherited from Query_result
	Query_result ()
virtual	~Query_result ()=default
virtual bool	needs_file_privilege () const
virtual bool	export_result_to_object_storage () const
	Returns true if the data has to be exported to object store. More...
virtual bool	change_query_result (THD *, Query_result *)
	Change wrapped Query_result. More...
virtual bool	need_explain_interceptor () const
virtual bool	start_execution (THD *)
	Prepare for execution of the query expression or DML statement. More...
virtual bool	create_table_for_query_block (THD *)
	Create table, only needed to support CREATE TABLE ... SELECT. More...
virtual bool	check_supports_cursor () const
	Check if this query result set supports cursors. More...
virtual void	abort_result_set (THD *)
virtual bool	use_protocol_adapter () const
virtual bool	use_protocol_wrapper () const
virtual Server_side_cursor *	cursor () const
virtual Table_ref *	get_create_table () const

Public Attributes
TABLE *	table
Public Attributes inherited from Query_result
ha_rows	estimated_rowcount
	Number of records estimated in this result. More...
double	estimated_cost
	Cost to execute the subquery which produces this result. More...

Protected Attributes
Temp_table_param	tmp_table_param
Protected Attributes inherited from Query_result
Query_expression *	unit

Friends
class	Common_table_expr
bool	Table_ref::create_materialized_table (THD *thd)
bool	Table_ref::optimize_derived (THD *thd)

Constructor & Destructor Documentation

Query_result_union()

Query_result_union::Query_result_union ( )

inline

Member Function Documentation

cleanup()

void Query_result_union::cleanup ( void  )

inlineoverridevirtual

Cleanup after this execution.

Completes the execution and resets object before next execution of a prepared statement/stored procedure.

Reimplemented from Query_result.

create_result_table()

bool Query_result_union::create_result_table	(	THD *	thd_arg,
		const mem_root_deque< Item * > &	column_types,
		bool	is_union_distinct,
		ulonglong	options,
		const char *	table_alias,
		bool	create_table,
		Query_term_set_op *	op = nullptr
	)

Create a temporary table to store the result of a query expression (used, among others, when materializing a UNION DISTINCT).

Parameters

thd_arg	thread handle
column_types	a list of items used to define columns of the temporary table
is_union_distinct	if set, the temporary table will eliminate duplicates on insert
options	create options
table_alias	name of the temporary table
create_table	If false, a table handler will not be created when creating the result table.
op	If we are creating a result table for a set operation, op should contain the relevant set operation's query term. In other cases, op should be nullptr.

Create a temporary table that is used to store the result of a UNION, derived table, or a materialized cursor.

Returns

false if table created, true if error

flush()

bool Query_result_union::flush ( )

virtual

Reimplemented in Query_result_union_direct.

get_hidden_field_count()

uint Query_result_union::get_hidden_field_count ( ) const

inline

postponed_prepare()

virtual bool Query_result_union::postponed_prepare ( THD *  thd, const mem_root_deque< Item * > &  types  )

inlinevirtual

Do prepare() if preparation has been postponed until column type information is computed (used by Query_result_union_direct).

Parameters

thd	Thread handle
types	Column types

Returns

false on success, true on failure

Reimplemented in Query_result_union_direct.

prepare()

bool Query_result_union::prepare ( THD *  , const mem_root_deque< Item * > &  , Query_expression *  u  )

overridevirtual

Perform preparation specific to the query expression or DML statement.

Returns

false if success, true if error

Reimplemented from Query_result.

reset()

bool Query_result_union::reset ( void  )

overridevirtual

Reset and empty the temporary table that stores the materialized query result.

Note

The cleanup performed here is exactly the same as for the two temp tables of JOIN - exec_tmp_table_[1 | 2].

Reimplemented from Query_result.

send_data()

bool Query_result_union::send_data ( THD *  thd, const mem_root_deque< Item * > &  items  )

overridevirtual

Implements Query_result.

send_eof()

bool Query_result_union::send_eof ( THD *  thd )

overridevirtual

Implements Query_result.

set_limit()

void Query_result_union::set_limit ( ha_rows  limit_rows )

overridevirtual

Set an effective LIMIT for the number of rows coming out of a materialized temporary table used for implementing INTERSECT or EXCEPT: informs TableScanIterator::TableScanIterator how many rows to read from the materialized table.

For UNION and simple tables the limitation is enforced earlier, at materialize time, but this is not possible for INTERSECT and EXCEPT due to the use of cardinality counters.

Parameters

limit_rows

the effective limit, or HA_POS_ERROR if none.

Reimplemented from Query_result.

skip_create_table()

bool Query_result_union::skip_create_table ( ) const

inline

Friends And Related Function Documentation

Common_table_expr

friend class Common_table_expr

friend

Table_ref::create_materialized_table

bool Table_ref::create_materialized_table ( THD *  thd )

friend

Table_ref::optimize_derived

bool Table_ref::optimize_derived ( THD *  thd )

friend

Member Data Documentation

table

TABLE* Query_result_union::table

tmp_table_param

Temp_table_param Query_result_union::tmp_table_param

protected

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

• sql/sql_union.h
• sql/sql_union.cc