EXPLAIN functionality for Query_result_insert, Query_result_update and Query_result_delete. More...

#include <opt_explain.h>

Inheritance diagram for Query_result_explain:

Public Member Functions
	Query_result_explain (Query_expression unit_arg, Query_result interceptor_arg)

Public Member Functions inherited from Query_result_send
	Query_result_send ()

bool	send_result_set_metadata (THD thd, const mem_root_deque< Item > &list, uint flags) override

bool	send_data (THD thd, const mem_root_deque< Item > &items) override

bool	send_eof (THD *thd) override

bool	check_supports_cursor () const override
	Check if this query result set supports cursors. More...

void	abort_result_set (THD *thd) override

void	cleanup () override
	Cleanup after this execution. More...

Public Member Functions inherited from Query_result
	Query_result ()

virtual	~Query_result ()=default

virtual bool	needs_file_privilege () const

virtual bool	change_query_result (THD , Query_result )
	Change wrapped Query_result. More...

virtual bool	need_explain_interceptor () const

virtual bool	create_table_for_query_block (THD *)
	Create table, only needed to support CREATE TABLE ... SELECT. More...

virtual uint	field_count (const mem_root_deque< Item * > &fields) const

virtual bool	reset ()
	Cleanup after one execution of the unit, to be ready for a next execution inside the same statement. More...

virtual bool	is_interceptor () const
	Checks if this Query_result intercepts and transforms the result set. More...

virtual void	set_limit (ha_rows)
	Only overridden (and non-empty) for Query_result_union, q.v. More...

virtual Server_side_cursor *	cursor () const

Protected Member Functions
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...

bool	start_execution (THD *thd) override
	Prepare for execution of the query expression or DML statement. More...

void	cleanup () override
	Cleanup after this execution. More...

Protected Attributes
Query_result *	interceptor
	Pointer to underlying Query_result_insert, Query_result_update or Query_result_delete object. More...

Protected Attributes inherited from Query_result
Query_expression *	unit

Additional Inherited Members
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...

Detailed Description

EXPLAIN functionality for Query_result_insert, Query_result_update and Query_result_delete.

This class objects substitute Query_result_insert, Query_result_update and Query_result_delete data interceptor objects to implement EXPLAIN for INSERT, REPLACE and multi-table UPDATE and DELETE queries. Query_result_explain class object initializes tables like Query_result_insert, Query_result_update or Query_result_delete data interceptor do, but it suppresses table data modification by the underlying interceptor object. Thus, we can use Query_result_explain object in the context of EXPLAIN INSERT/ REPLACE/UPDATE/DELETE query like we use Query_result_send in the context of EXPLAIN SELECT command: 1) in presence of lex->describe flag, pass Query_result_explain object to execution function, 2) it calls prepare(), optimize() and start_execution() functions to mark modified tables etc.

Constructor & Destructor Documentation

◆ Query_result_explain()

Query_result_explain::Query_result_explain	(	Query_expression *	unit_arg,
		Query_result *	interceptor_arg
	)

inline

Member Function Documentation

◆ cleanup()

void Query_result_explain::cleanup ( )

inlineoverrideprotectedvirtual

Cleanup after this execution.

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

Reimplemented from Query_result.

◆ prepare()

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

inlineoverrideprotectedvirtual

Perform preparation specific to the query expression or DML statement.

Returns: false if success, true if error

Reimplemented from Query_result.

◆ start_execution()

bool Query_result_explain::start_execution ( THD * )

inlineoverrideprotectedvirtual

Prepare for execution of the query expression or DML statement.

Generally, this will have an implementation only for outer-most Query_block objects, such as data change statements (for preparation of the target table(s)) or dump statements (for preparation of target file).

Returns: false if success, true if error

Reimplemented from Query_result.

Member Data Documentation

◆ interceptor

Query_result* Query_result_explain::interceptor

protected

Pointer to underlying Query_result_insert, Query_result_update or Query_result_delete object.

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

sql/opt_explain.h

Public Member Functions

Protected Member Functions

Protected Attributes

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

◆ Query_result_explain()

Member Function Documentation

◆ cleanup()

◆ prepare()

◆ start_execution()

Member Data Documentation

◆ interceptor