This class outputs an empty plan for queries that use a secondary engine. More...

Inheritance diagram for anonymous_namespace{opt_explain.cc}::Explain_secondary_engine:

Public Member Functions
	Explain_secondary_engine (THD explain_thd_arg, const THD query_thd_arg, Query_block *query_block_arg)

Public Member Functions inherited from anonymous_namespace{opt_explain.cc}::Explain
virtual	~Explain ()=default

bool	send ()
	Explain class main function. More...

bool	can_print_clauses () const
	Tells if it is allowed to print the WHERE / GROUP BY / etc clauses. More...

Protected Member Functions
bool	explain_select_type () override

bool	explain_extra () override

Protected Member Functions inherited from anonymous_namespace{opt_explain.cc}::Explain
	Explain (enum_parsing_context context_type_arg, THD explain_thd_arg, const THD query_thd_arg, Query_block *query_block_arg)

virtual bool	shallow_explain ()
	Explain everything but subqueries. More...

bool	explain_subqueries ()
	Explain the rest of things after the `shallow_explain()` call. More...

bool	mark_subqueries (Item item, qep_row destination)
	Qualify subqueries with WHERE/HAVING/ORDER BY/GROUP BY clause type marker. More...

bool	prepare_columns ()
	Pre-calculate table property values for further EXPLAIN output. More...

bool	push_extra (Extra_tag tag)
	Push a part of the "extra" column into formatter. More...

bool	push_extra (Extra_tag tag, const String &arg)
	Push a part of the "extra" column into formatter. More...

bool	push_extra (Extra_tag tag, const char *arg)
	Push a part of the "extra" column into formatter. More...

virtual bool	explain_id ()

virtual bool	explain_table_name ()

virtual bool	explain_partitions ()

virtual bool	explain_join_type ()

virtual bool	explain_possible_keys ()

virtual bool	explain_key_and_len ()
	fill col_key and and col_key_len fields together More...

virtual bool	explain_ref ()

virtual bool	explain_rows_and_filtered ()
	fill col_rows and col_filtered fields together More...

virtual bool	explain_modify_flags ()

virtual bool	can_walk_clauses ()
	Returns true if the WHERE, ORDER BY, GROUP BY, etc clauses can safely be traversed: it means that we can iterate through them (no element is added/removed/replaced); the internal details of an element can change though (in particular if that element is an Item_subselect). More...

virtual enum_parsing_context	get_subquery_context (Query_expression *unit) const

Private Member Functions
bool	skip_subqueries () const override
	Returns true if EXPLAIN should not produce any information about subqueries. More...

Additional Inherited Members
Protected Attributes inherited from anonymous_namespace{opt_explain.cc}::Explain
THD *const	explain_thd
	cached THD which runs the EXPLAIN command More...

const THD *	query_thd
	THD which runs the query to be explained. More...

const CHARSET_INFO *const	cs
	cached pointer to system_charset_info More...

Query_block *const	query_block
	Cached Query_block of the explained query. More...

Explain_format *const	fmt
	shortcut for thd->lex->explain_format More...

enum_parsing_context	context_type
	associated value for struct. explain More...

bool	order_list
	if query block has ORDER BY More...

const bool	explain_other
	if we explain other thread than us More...

Detailed Description

This class outputs an empty plan for queries that use a secondary engine.

It is only used with the hypergraph optimizer, and only when the traditional format is specified. The traditional format is not supported by the hypergraph optimizer, so only an empty plan is shown, with extra information showing a secondary engine is used.

Constructor & Destructor Documentation

◆ Explain_secondary_engine()

anonymous_namespace{opt_explain.cc}::Explain_secondary_engine::Explain_secondary_engine	(	THD *	explain_thd_arg,
		const THD *	query_thd_arg,
		Query_block *	query_block_arg
	)

inline

Member Function Documentation

◆ explain_extra()

bool anonymous_namespace{opt_explain.cc}::Explain_secondary_engine::explain_extra ( )

inlineoverrideprotectedvirtual

Reimplemented from anonymous_namespace{opt_explain.cc}::Explain.

◆ explain_select_type()

bool anonymous_namespace{opt_explain.cc}::Explain_secondary_engine::explain_select_type ( )

inlineoverrideprotectedvirtual

Reimplemented from anonymous_namespace{opt_explain.cc}::Explain.

◆ skip_subqueries()

bool anonymous_namespace{opt_explain.cc}::Explain_secondary_engine::skip_subqueries ( ) const

inlineoverrideprivatevirtual

Returns true if EXPLAIN should not produce any information about subqueries.

Reimplemented from anonymous_namespace{opt_explain.cc}::Explain.

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

sql/opt_explain.cc

Public Member Functions

Protected Member Functions

Private Member Functions

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

◆ Explain_secondary_engine()

Member Function Documentation

◆ explain_extra()

◆ explain_select_type()

◆ skip_subqueries()