Plan_change_watchdog Class Reference

It is not obvious to see that test_if_skip_sort_order() never changes the plan if no_changes is true. More...

Public Member Functions
	Plan_change_watchdog (const JOIN_TAB *tab_arg, const bool no_changes_arg)
	~Plan_change_watchdog ()

Private Attributes
const JOIN_TAB *	tab
	table, or NULL if changes are allowed More...
enum join_type	type
	copy of tab->type() More...
const AccessPath *	quick {nullptr}
	copy of tab->select->quick More...
uint	quick_index {0}
	copy of tab->select->quick->index More...
enum quick_type	use_quick
	copy of tab->use_quick More...
int	ref_key
	copy of tab->ref().key More...
uint	ref_key_parts
uint	index
	copy of tab->ref().key_parts More...

Detailed Description

It is not obvious to see that test_if_skip_sort_order() never changes the plan if no_changes is true.

So we double-check: creating an instance of this class saves some important access-path-related information of the current table; when the instance is destroyed, the latest access-path information is compared with saved data.

Constructor & Destructor Documentation

Plan_change_watchdog()

Plan_change_watchdog::Plan_change_watchdog ( const JOIN_TAB *  tab_arg, const bool  no_changes_arg  )

inline

Parameters

tab_arg	table whose access path is being determined
no_changes_arg	whether a change to the access path is allowed

~Plan_change_watchdog()

Plan_change_watchdog::~Plan_change_watchdog ( )

inline

Member Data Documentation

index

uint Plan_change_watchdog::index

private

copy of tab->ref().key_parts

copy of tab->index

quick

const AccessPath* Plan_change_watchdog::quick {nullptr}

private

copy of tab->select->quick

quick_index

uint Plan_change_watchdog::quick_index {0}

private

copy of tab->select->quick->index

ref_key

int Plan_change_watchdog::ref_key

private

copy of tab->ref().key

ref_key_parts

uint Plan_change_watchdog::ref_key_parts

private

tab

const JOIN_TAB* Plan_change_watchdog::tab

private

table, or NULL if changes are allowed

type

enum join_type Plan_change_watchdog::type

private

copy of tab->type()

use_quick

enum quick_type Plan_change_watchdog::use_quick

private

copy of tab->use_quick

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

• sql/sql_optimizer.cc