This class represents a query expression (one query block or several query blocks combined with UNION). More...

#include <sql_lex.h>

Public Types
enum	enum_clean_state { UC_DIRTY , UC_PART_CLEAN , UC_CLEAN }
	Values for Query_expression::cleaned. More...

Public Member Functions
Query_term *	query_term () const
	Getter for m_query_term, q.v. More...

void	set_query_term (Query_term *qt)
	Setter for m_query_term, q.v. More...

Query_term_set_op *	set_operation () const
	Convenience method to avoid down casting, i.e. More...

Query_block *	non_simple_result_query_block () const
	Return the query block iff !is_simple() holds. More...

bool	is_leaf_block (Query_block *qb)

Query_term *	find_blocks_query_term (const Query_block *qb) const

template<Visit_order order = QTC_POST_ORDER, Visit_leaves visit_leaves = VL_VISIT_LEAVES>
Query_terms< order, visit_leaves >	query_terms () const
	Return iterator object over query terms rooted in m_query_term, using either post order visiting (default) or pre order, optionally skipping leaf nodes (query blocks corresponding to SELECTs or table constructors). More...

Query_block *	last_distinct () const
	Return the Query_block of the last query term in a n-ary set operation that is the right side of the last DISTINCT set operation in that n_ary set operation: E.e. More...

bool	has_top_level_distinct () const

	Query_expression (enum_parsing_context parsing_context)
	Construct and initialize Query_expression object. More...

bool	is_simple () const

Query_block *	global_parameters () const
	Return the query block holding the top level ORDER BY, LIMIT and OFFSET. More...

bool	is_mergeable () const
	Return true if query expression can be merged into an outer query, based on technical constraints. More...

bool	merge_heuristic (const LEX *lex) const
	True if heuristics suggest to merge this query expression. More...

Query_block *	outer_query_block () const

Query_block *	first_query_block () const

Query_expression *	next_query_expression () const

Query_result *	query_result () const

RowIterator *	root_iterator () const

unique_ptr_destroy_only< RowIterator >	release_root_iterator ()

AccessPath *	root_access_path () const

void	change_to_access_path_without_in2exists (THD *thd)

void	clear_root_access_path ()

bool	force_create_iterators (THD *thd)
	Ensures that there are iterators created for the access paths created by optimize(), even if it was called with create_access_paths = false. More...

bool	unfinished_materialization () const
	See optimize(). More...

Mem_root_array< MaterializePathParameters::QueryBlock >	release_query_blocks_to_materialize ()
	See optimize(). More...

void	set_query_result (Query_result *res)
	Set new query result object for this query expression. More...

bool	can_materialize_directly_into_result () const
	Whether there is a chance that optimize() is capable of materializing directly into a result table if given one. More...

bool	prepare (THD thd, Query_result result, mem_root_deque< Item * > *insert_field_list, ulonglong added_options, ulonglong removed_options)
	Prepares all query blocks of a query expression. More...

bool	optimize (THD thd, TABLE materialize_destination, bool create_iterators, bool finalize_access_paths)
	If and only if materialize_destination is non-nullptr, it means that the caller intends to materialize our result into the given table. More...

bool	finalize (THD *thd)
	For any non-finalized query block, finalize it so that we are allowed to create iterators. More...

bool	ClearForExecution ()
	Do everything that would be needed before running Init() on the root iterator. More...

bool	ExecuteIteratorQuery (THD *thd)

bool	execute (THD *thd)
	Execute a query expression that may be a UNION and/or have an ordered result. More...

bool	explain (THD explain_thd, const THD query_thd)
	Explain query starting from this unit. More...

bool	explain_query_term (THD explain_thd, const THD query_thd, Query_term *qt)

void	cleanup (bool full)
	Cleanup this query expression object after preparation or one round of execution. More...

void	destroy ()
	Destroy contained objects, in particular temporary tables which may have their own mem_roots. More...

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

bool	accept (Select_lex_visitor *visitor)

Query_block *	create_post_processing_block (Query_term_set_op *term)
	Create a block to be used for ORDERING and LIMIT/OFFSET processing of a query term, which isn't itself a query specification or table value constructor. More...

bool	prepare_query_term (THD thd, Query_term qts, Query_result *common_result, ulonglong added_options, ulonglong create_options, int level, Mem_root_array< bool > &nullable)
	Prepare the query term nodes and their associated post processing query blocks (i.e. More...

void	set_prepared ()

void	set_optimized ()

void	set_executed ()

void	reset_executed ()
	Reset this query expression for repeated evaluation within same execution. More...

void	clear_execution ()
	Clear execution state, needed before new execution of prepared statement. More...

bool	is_prepared () const
	Check state of preparation of the contained query expression. More...

bool	is_optimized () const
	Check state of optimization of the contained query expression. More...

bool	is_executed () const
	Check state of execution of the contained query expression. More...

bool	change_query_result (THD thd, Query_result_interceptor result, Query_result_interceptor *old_result)
	Change the query result object used to return the final result of the unit, replacing occurrences of old_result with new_result. More...

bool	set_limit (THD thd, Query_block provider)
	Set limit and offset for query expression object. More...

bool	has_any_limit () const
	Checks if this query expression has limit defined. More...

bool	is_union () const

bool	is_set_operation () const

void	include_down (LEX lex, Query_block outer)
	Include a query expression below a query block. More...

void	exclude_level ()
	Exclude this unit and immediately contained query_block objects. More...

void	exclude_tree ()
	Exclude subtree of current unit from tree of SELECTs. More...

void	renumber_selects (LEX *lex)
	Renumber query blocks of a query expression according to supplied LEX. More...

void	restore_cmd_properties ()
	Loop over all query blocks and restore information needed for optimization, including binding data for all associated tables. More...

bool	save_cmd_properties (THD *thd)
	Save prepared statement properties for a query expression and underlying query blocks. More...

mem_root_deque< Item * > *	get_unit_column_types ()
	Get column type information for this query expression. More...

mem_root_deque< Item * > *	get_field_list ()
	Get field list for this query expression. More...

size_t	num_visible_fields () const

enum_parsing_context	get_explain_marker (const THD *thd) const

void	set_explain_marker (THD *thd, enum_parsing_context m)

void	set_explain_marker_from (THD thd, const Query_expression u)

void	assert_not_fully_clean ()
	Asserts that none of {this unit and its children units} is fully cleaned up. More...

void	invalidate ()
	Invalidate by nulling out pointers to other Query expressions and Query blocks. More...

bool	is_recursive () const

bool	check_materialized_derived_query_blocks (THD *thd)
	Sets up query blocks belonging to the query expression of a materialized derived table. More...

bool	clear_correlated_query_blocks ()
	Empties all correlated query blocks defined within the query expression; that is, correlated CTEs defined in the expression's WITH clause, and correlated derived tables. More...

void	fix_after_pullout (Query_block parent_query_block, Query_block removed_query_block)
	Fix used tables information for a subquery after query transformations. More...

void	accumulate_used_tables (table_map map)
	If unit is a subquery, which forms an object of the upper level (an Item_subselect, a derived Table_ref), adds to this object a map of tables of the upper level which the unit references. More...

enum_parsing_context	place () const
	If unit is a subquery, which forms an object of the upper level (an Item_subselect, a derived Table_ref), returns the place of this object in the upper level query block. More...

bool	walk (Item_processor processor, enum_walk walk, uchar *arg)

Public Attributes
uint8	uncacheable
	result of this query can't be cached, bit field, can be : UNCACHEABLE_DEPENDENT UNCACHEABLE_RAND UNCACHEABLE_SIDEEFFECT More...

enum_clean_state	cleaned
	cleanliness state More...

ha_rows	select_limit_cnt

ha_rows	offset_limit_cnt

Item_subselect *	item
	Points to subquery if this query expression is used in one, otherwise NULL. More...

PT_with_clause *	m_with_clause
	The WITH clause which is the first part of this query expression. More...

Table_ref *	derived_table
	If this query expression is underlying of a derived table, the derived table. More...

Query_block *	first_recursive
	First query block (in this UNION) which references the CTE. More...

table_map	m_lateral_deps
	If 'this' is body of lateral derived table: map of tables in the same FROM clause as this derived table, and to which the derived table's body makes references. More...

bool	m_reject_multiple_rows {false}
	This query expression represents a scalar subquery and we need a run-time check that the cardinality doesn't exceed 1. More...

ha_rows	send_records

Private Member Functions
void	create_access_paths (THD *thd)
	Convert the executor structures to a set of access paths, storing the result in m_root_access_path. More...

Private Attributes
Query_expression *	next
	Intrusive double-linked list of all query expressions immediately contained within the same query block. More...

Query_expression **	prev

Query_block *	master
	The query block wherein this query expression is contained, NULL if the query block is the outer-most one. More...

Query_block *	slave
	The first query block in this query expression. More...

Query_term *	m_query_term {nullptr}

enum_parsing_context	explain_marker
	Marker for subqueries in WHERE, HAVING, ORDER BY, GROUP BY and SELECT item lists. More...

bool	prepared
	All query blocks in query expression are prepared. More...

bool	optimized
	All query blocks in query expression are optimized. More...

bool	executed
	Query expression has been executed. More...

Query_result *	m_query_result
	Object to which the result for this query expression is sent. More...

unique_ptr_destroy_only< RowIterator >	m_root_iterator
	An iterator you can read from to get all records for this query. More...

AccessPath *	m_root_access_path = nullptr

Mem_root_array< MaterializePathParameters::QueryBlock >	m_query_blocks_to_materialize
	If there is an unfinished materialization (see optimize()), contains one element for each query block in this query expression. More...

mem_root_deque< Item * >	types

Friends
class	Query_block

bool	parse_view_definition (THD thd, Table_ref view_ref)
	Parse a view definition. More...

Detailed Description

This class represents a query expression (one query block or several query blocks combined with UNION).

Member Enumeration Documentation

◆ enum_clean_state

enum Query_expression::enum_clean_state

Values for Query_expression::cleaned.

Enumerator
UC_DIRTY	Unit isn't cleaned.
UC_PART_CLEAN	Unit were cleaned, except JOIN and JOIN_TABs were kept for possible EXPLAIN.
UC_CLEAN	Unit completely cleaned, all underlying JOINs were freed.

Constructor & Destructor Documentation

◆ Query_expression()

Query_expression::Query_expression ( enum_parsing_context parsing_context )

explicit

Construct and initialize Query_expression object.

Member Function Documentation

◆ accept()

bool Query_expression::accept ( Select_lex_visitor * visitor )

◆ accumulate_used_tables()

void Query_expression::accumulate_used_tables ( table_map map )

If unit is a subquery, which forms an object of the upper level (an Item_subselect, a derived Table_ref), adds to this object a map of tables of the upper level which the unit references.

◆ assert_not_fully_clean()

void Query_expression::assert_not_fully_clean ( )

Asserts that none of {this unit and its children units} is fully cleaned up.

◆ can_materialize_directly_into_result()

bool Query_expression::can_materialize_directly_into_result ( ) const

Whether there is a chance that optimize() is capable of materializing directly into a result table if given one.

Note that even if this function returns true, optimize() can choose later not to do so, since it depends on information (in particular, whether the query blocks can run under the iterator executor or not) that is not available before optimize time.

TODO(sgunders): Now that all query blocks can run under the iterator executor, the above may no longer be true. This needs investigation.

◆ change_query_result()

bool Query_expression::change_query_result	(	THD *	thd,
		Query_result_interceptor *	new_result,
		Query_result_interceptor *	old_result
	)

Change the query result object used to return the final result of the unit, replacing occurrences of old_result with new_result.

Parameters

thd	Thread handle
new_result	New query result object
old_result	Old query result object

Return values

false	Success
true	Error

◆ change_to_access_path_without_in2exists()

void Query_expression::change_to_access_path_without_in2exists ( THD * thd )

◆ check_materialized_derived_query_blocks()

bool Query_expression::check_materialized_derived_query_blocks ( THD * thd_arg )

Sets up query blocks belonging to the query expression of a materialized derived table.

Parameters

thd_arg THD pointer

Returns: false if successful, true if error

◆ cleanup()

void Query_expression::cleanup ( bool full )

Cleanup this query expression object after preparation or one round of execution.

After the cleanup, the object can be reused for a new round of execution, but a new optimization will be needed before the execution.

◆ clear_correlated_query_blocks()

bool Query_expression::clear_correlated_query_blocks ( )

Empties all correlated query blocks defined within the query expression; that is, correlated CTEs defined in the expression's WITH clause, and correlated derived tables.

◆ clear_execution()

void Query_expression::clear_execution ( )

inline

Clear execution state, needed before new execution of prepared statement.

◆ clear_root_access_path()

void Query_expression::clear_root_access_path ( )

inline

◆ ClearForExecution()

bool Query_expression::ClearForExecution ( )

Do everything that would be needed before running Init() on the root iterator.

In particular, clear out data from previous execution iterations, if needed.

◆ create_access_paths()

void Query_expression::create_access_paths ( THD * thd )

private

Convert the executor structures to a set of access paths, storing the result in m_root_access_path.

◆ create_post_processing_block()

Query_block * Query_expression::create_post_processing_block ( Query_term_set_op * term )

Create a block to be used for ORDERING and LIMIT/OFFSET processing of a query term, which isn't itself a query specification or table value constructor.

Such blocks are not included in the list starting in Query_Expression::first_query_block, and Query_block::next_query_block(). They blocks are accessed via Query_term::query_block().

Parameters

term	the term on behalf of which we are making a post processing block

Returns: a query block

◆ destroy()

void Query_expression::destroy ( )

Destroy contained objects, in particular temporary tables which may have their own mem_roots.

◆ exclude_level()

void Query_expression::exclude_level ( )

Exclude this unit and immediately contained query_block objects.

Exclude this query expression and its immediately contained query terms and query blocks from AST.

Note: Query expressions that belong to the query_block objects of the current query expression will be brought up one level and will replace the current query expression in the list inside the outer query block.

◆ exclude_tree()

void Query_expression::exclude_tree ( )

Exclude subtree of current unit from tree of SELECTs.

Exclude current query expression with all underlying query terms, query blocks and query expressions from AST.

◆ execute()

bool Query_expression::execute ( THD * thd )

Execute a query expression that may be a UNION and/or have an ordered result.

Parameters

thd	thread handle

Returns: false if success, true if error

◆ ExecuteIteratorQuery()

bool Query_expression::ExecuteIteratorQuery ( THD * thd )

◆ explain()

bool Query_expression::explain	(	THD *	explain_thd,
		const THD *	query_thd
	)

Explain query starting from this unit.

Parameters

explain_thd	thread handle for the connection doing explain
query_thd	thread handle for the connection being explained

Returns: false if success, true if error

◆ explain_query_term()

bool Query_expression::explain_query_term	(	THD *	explain_thd,
		const THD *	query_thd,
		Query_term *	qt
	)

◆ finalize()

bool Query_expression::finalize ( THD * thd )

For any non-finalized query block, finalize it so that we are allowed to create iterators.

Must be called after the final access path is chosen (ie., after any calls to change_to_access_path_without_in2exists()).

◆ find_blocks_query_term()

Query_term * Query_expression::find_blocks_query_term ( const Query_block * qb ) const

inline

◆ first_query_block()

Query_block * Query_expression::first_query_block ( ) const

inline

Returns: the first query block inside this query expression

◆ force_create_iterators()

bool Query_expression::force_create_iterators ( THD * thd )

Ensures that there are iterators created for the access paths created by optimize(), even if it was called with create_access_paths = false.

If there are already iterators, it is a no-op. optimize() must have been called earlier.

The use case for this is if we have a query block that's not top-level, but we figure out after the fact that we wanted to run it anyway. The typical case would be that we notice that the query block can return at most one row (a so-called const table), and want to run it during optimization.

◆ get_explain_marker()

enum_parsing_context Query_expression::get_explain_marker ( const THD * thd ) const

◆ get_field_list()

mem_root_deque< Item * > * Query_expression::get_field_list ( )

Get field list for this query expression.

For a UNION of query blocks, return the field list generated during prepare. For a single query block, return the field list after all possible intermediate query processing steps are done (optimization is complete).

Returns: List containing fields of the query expression.

◆ get_unit_column_types()

mem_root_deque< Item * > * Query_expression::get_unit_column_types ( )

Get column type information for this query expression.

For a single query block the column types are taken from the list of selected items of this block.

For a union this function assumes that the type holders were created for unioned column types of all query blocks, by Query_expression::prepare().

Note: The implementation of this function should be in sync with Query_expression::prepare()

Returns: List of items as specified in function description. May contain hidden fields (item->hidden = true), so the caller needs to be able to filter them out.

◆ global_parameters()

Query_block * Query_expression::global_parameters ( ) const

inline

Return the query block holding the top level ORDER BY, LIMIT and OFFSET.

If the query is not a set operation (UNION, INTERSECT or EXCEPT, and the query expression has no multi-level ORDER BY/LIMIT, this represents the single query block of the query itself, cf. documentation for class Query_term.

Returns: query block containing the global parameters

◆ has_any_limit()

bool Query_expression::has_any_limit ( ) const

Checks if this query expression has limit defined.

For a query expression with set operation it checks if any of the query blocks has limit defined.

Returns: true if the query expression has limit. false otherwise.

◆ has_top_level_distinct()

bool Query_expression::has_top_level_distinct ( ) const

inline

◆ include_down()

void Query_expression::include_down	(	LEX *	lex,
		Query_block *	outer
	)

Include a query expression below a query block.

Parameters

lex	Containing LEX object
outer	The query block that this query expression is included below.

◆ invalidate()

void Query_expression::invalidate ( )

Invalidate by nulling out pointers to other Query expressions and Query blocks.

◆ is_executed()

bool Query_expression::is_executed ( ) const

inline

Check state of execution of the contained query expression.

Should not be used to check the state of a complete statement, use LEX::is_exec_completed() instead.

◆ is_leaf_block()

bool Query_expression::is_leaf_block ( Query_block * qb )

◆ is_mergeable()

bool Query_expression::is_mergeable ( ) const

Return true if query expression can be merged into an outer query, based on technical constraints.

Returns: true if query expression can be merged into an outer query

Being mergeable also means that derived table/view is updatable.

A view/derived table is not mergeable if it is one of the following:

A set operation (implementation restriction).
An aggregated query, or has HAVING, or has DISTINCT (A general aggregated query cannot be merged with a non-aggregated one).
A table-less query (unimportant special case).
A query with a LIMIT (limit applies to subquery, so the implementation strategy is to materialize this subquery, including row count constraint).
It has windows

◆ is_optimized()

bool Query_expression::is_optimized ( ) const

inline

Check state of optimization of the contained query expression.

◆ is_prepared()

bool Query_expression::is_prepared ( ) const

inline

Check state of preparation of the contained query expression.

◆ is_recursive()

bool Query_expression::is_recursive ( ) const

inline

◆ is_simple()

bool Query_expression::is_simple ( ) const

inline

Returns: true for a query expression without UNION/INTERSECT/EXCEPT or multi-level ORDER, i.e. we have a "simple table".

◆ last_distinct()

Query_block * Query_expression::last_distinct ( ) const

inline

Return the Query_block of the last query term in a n-ary set operation that is the right side of the last DISTINCT set operation in that n_ary set operation: E.e.

for A UNION B UNION ALL C, B's block will be returned. If no DISTINCT is present or not a set operation, return nullptr.

Returns: query block of last distinct right operand

◆ merge_heuristic()

bool Query_expression::merge_heuristic ( const LEX * lex ) const

True if heuristics suggest to merge this query expression.

Returns: true if query expression is recommended to be merged

A view/derived table is not suggested for merging if it contains subqueries in the SELECT list that depend on columns from itself. Merging such objects is possible, but we assume they are made derived tables because the user wants them to be materialized, for performance reasons.

One possible case is a derived table with dependent subqueries in the select list, used as the inner table of a left outer join. Such tables will always be read as many times as there are qualifying rows in the outer table, and the select list subqueries are evaluated for each row combination. The select list subqueries are evaluated the same number of times also with join buffering enabled, even though the table then only will be read once.

Another case is, a query that modifies variables: then try to preserve the original structure of the query. This is less likely to cause changes in variable assignment order.

◆ next_query_expression()

Query_expression * Query_expression::next_query_expression ( ) const

inline

Returns: the next query expression within same query block (next subquery)

◆ non_simple_result_query_block()

Query_block * Query_expression::non_simple_result_query_block ( ) const

inline

Return the query block iff !is_simple() holds.

◆ num_visible_fields()

size_t Query_expression::num_visible_fields ( ) const

◆ optimize()

bool Query_expression::optimize	(	THD *	thd,
		TABLE *	materialize_destination,
		bool	create_iterators,
		bool	finalize_access_paths
	)

If and only if materialize_destination is non-nullptr, it means that the caller intends to materialize our result into the given table.

If it is advantageous (in particular, if this query expression is a UNION DISTINCT), optimize() will not create an iterator by itself, but rather do an unfinished materialize. This means that it will collect iterators for all the query blocks and prepare them for materializing into the given table, but not actually create a root iterator for this query expression; the caller is responsible for calling release_query_blocks_to_materialize() and creating the iterator itself.

Even if materialize_destination is non-nullptr, this function may choose to make a regular iterator. The caller is responsible for checking unfinished_materialization() if it has given a non-nullptr table.

Parameters

thd	Thread handle.
materialize_destination	What table to try to materialize into, or nullptr if the caller does not intend to materialize the result.
create_iterators	If false, only access paths are created, not iterators. Only top level query blocks (these that we are to call exec() on) should have iterators. See also force_create_iterators().
finalize_access_paths	Relevant for the hypergraph optimizer only. If false, the given access paths will not be finalized, so you cannot create iterators from it before finalize() is called (see FinalizePlanForQueryBlock()), and create_iterators must also be false. This is relevant only if you are potentially optimizing multiple times (see change_to_access_path_without_in2exists()), since you are only allowed to finalize a query block once. "Fake" query blocks (see query_term.h) are always finalized.

◆ outer_query_block()

Query_block * Query_expression::outer_query_block ( ) const

inline

Returns: the query block this query expression belongs to as subquery

◆ place()

enum_parsing_context Query_expression::place ( ) const

If unit is a subquery, which forms an object of the upper level (an Item_subselect, a derived Table_ref), returns the place of this object in the upper level query block.

◆ prepare()

bool Query_expression::prepare	(	THD *	thd,
		Query_result *	sel_result,
		mem_root_deque< Item * > *	insert_field_list,
		ulonglong	added_options,
		ulonglong	removed_options
	)

Prepares all query blocks of a query expression.

If a recursive query expression, this also creates the materialized temporary table.

Parameters

thd	Thread handler
sel_result	Result object where the unit's output should go.
insert_field_list	Pointer to field list if INSERT op, NULL otherwise.
added_options	These options will be added to the query blocks.
removed_options	Options that cannot be used for this query

Returns: false if success, true if error

◆ prepare_query_term()

bool Query_expression::prepare_query_term	(	THD *	thd,
		Query_term *	qt,
		Query_result *	common_result,
		ulonglong	added_options,
		ulonglong	create_options,
		int	level,
		Mem_root_array< bool > &	nullable
	)

Prepare the query term nodes and their associated post processing query blocks (i.e.

not the ones representing the query specifications), but rather ORDER BY/LIMIT processing (old "fake" query blocks). Also create temporary tables to consolidate set operations as needed, recursively.

Parameters

	thd	session context
	qt	the query term at the current level in the tree
	common_result	For the top node, this is not used: we use query_result() instead. Otherwise, if it is empty, we create one a query result behalf of this node and its siblings. This node is then the designated owning operand, and is responsible for releasing it after execution. The siblings will see that common_result is not empty and use that.
	added_options	options to add for the post processing query block
	create_options	options to use for creating tmp table
	level	the current level in the query expression's query term tree
[in,out]	nullable	computed nullability for the query's result set columns

Returns: false on success, true on error

We are part of upper level set op

◆ print()

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

◆ query_result()

Query_result * Query_expression::query_result ( ) const

inline

Returns: the query result object in use for this query expression

◆ query_term()

Query_term * Query_expression::query_term ( ) const

inline

Getter for m_query_term, q.v.

◆ query_terms()

template<Visit_order order = QTC_POST_ORDER, Visit_leaves visit_leaves = VL_VISIT_LEAVES>

Query_terms< order, visit_leaves > Query_expression::query_terms ( ) const

inline

Return iterator object over query terms rooted in m_query_term, using either post order visiting (default) or pre order, optionally skipping leaf nodes (query blocks corresponding to SELECTs or table constructors).

By default, we visit all nodes. Usage: for (auto qt : query_terms<..>() { ... } E.g. for (auto qt : query_terms<>()) { } Visit all nodes, post order for (auto qt : query_terms<QTC_PRE_ORDER, false>()) { } Skip leaves, pre order

Template Parameters

order	== QTC_POST_ORDER if post order traversal is desired;default == QTC_PRE_ORDER pre-order traversal
visit_leaves	== VL_VISIT_LEAVES: if we want the traversal to include leaf nodes i.e. the SELECTs or table constructors == VL_SKIP_LEAVES: leaves will be skipped

Returns: iterator object

◆ release_query_blocks_to_materialize()

Mem_root_array< MaterializePathParameters::QueryBlock > Query_expression::release_query_blocks_to_materialize ( )

inline

See optimize().

◆ release_root_iterator()

unique_ptr_destroy_only< RowIterator > Query_expression::release_root_iterator ( )

inline

◆ renumber_selects()

void Query_expression::renumber_selects ( LEX * lex )

Renumber query blocks of a query expression according to supplied LEX.

Renumber contained query_block objects.

Parameters

lex	Containing LEX object

◆ reset_executed()

void Query_expression::reset_executed ( )

inline

Reset this query expression for repeated evaluation within same execution.

◆ restore_cmd_properties()

void Query_expression::restore_cmd_properties ( )

Loop over all query blocks and restore information needed for optimization, including binding data for all associated tables.

◆ root_access_path()

AccessPath * Query_expression::root_access_path ( ) const

inline

◆ root_iterator()

RowIterator * Query_expression::root_iterator ( ) const

inline

◆ save_cmd_properties()

bool Query_expression::save_cmd_properties ( THD * thd )

Save prepared statement properties for a query expression and underlying query blocks.

Required for repeated optimizations of the command.

Parameters

thd	thread handler

Returns: false if success, true if error (out of memory)

◆ set_executed()

void Query_expression::set_executed ( )

inline

◆ set_explain_marker()

void Query_expression::set_explain_marker	(	THD *	thd,
		enum_parsing_context	m
	)

◆ set_explain_marker_from()

void Query_expression::set_explain_marker_from	(	THD *	thd,
		const Query_expression *	u
	)

◆ set_limit()

bool Query_expression::set_limit	(	THD *	thd,
		Query_block *	provider
	)

Set limit and offset for query expression object.

Parameters

thd	thread handler
provider	Query_block to get offset and limit from.

Returns: false if success, true if error

◆ set_operation()

Query_term_set_op * Query_expression::set_operation ( ) const

inline

Convenience method to avoid down casting, i.e.

interpret m_query_term as a Query_term_set_op.

Return values

a	non-null node iff !is_simple
nullptr	if is_simple() holds.

◆ set_optimized()

void Query_expression::set_optimized ( )

inline

◆ set_prepared()

void Query_expression::set_prepared ( )

inline

◆ set_query_result()

void Query_expression::set_query_result ( Query_result * res )

inline

Set new query result object for this query expression.

◆ set_query_term()

void Query_expression::set_query_term ( Query_term * qt )

inline

Setter for m_query_term, q.v.

◆ unfinished_materialization()

bool Query_expression::unfinished_materialization ( ) const

inline

See optimize().

◆ walk()

bool Query_expression::walk	(	Item_processor	processor,
		enum_walk	walk,
		uchar *	arg
	)

Friends And Related Function Documentation

◆ parse_view_definition

bool parse_view_definition	(	THD *	thd,
		Table_ref *	view_ref
	)

friend

Parse a view definition.

Among other effects, it adds underlying tables to the global list of tables, so the next iteration in open_tables() will open them.

Parameters

[in]	thd	Thread handler
[in,out]	view_ref	Table_ref structure for view reference

Returns: false-in case of success, true-in case of error.

Note: In case true value returned an error has been already set in DA.

◆ Query_block

friend class Query_block

friend

Member Data Documentation

◆ cleaned

enum_clean_state Query_expression::cleaned

cleanliness state

◆ derived_table

Table_ref* Query_expression::derived_table

If this query expression is underlying of a derived table, the derived table.

NULL if none.

◆ executed

bool Query_expression::executed

private

Query expression has been executed.

◆ explain_marker

enum_parsing_context Query_expression::explain_marker

private

Marker for subqueries in WHERE, HAVING, ORDER BY, GROUP BY and SELECT item lists.

Must be read/written when holding LOCK_query_plan.

See Item_subselect::explain_subquery_checker

◆ first_recursive

Query_block* Query_expression::first_recursive

First query block (in this UNION) which references the CTE.

NULL if not the query expression of a recursive CTE.

◆ item

Item_subselect* Query_expression::item

Points to subquery if this query expression is used in one, otherwise NULL.

◆ m_lateral_deps

table_map Query_expression::m_lateral_deps

If 'this' is body of lateral derived table: map of tables in the same FROM clause as this derived table, and to which the derived table's body makes references.

In pre-resolution stages, this is OUTER_REF_TABLE_BIT, just to indicate that this has LATERAL; after resolution, which has found references in the body, this is the proper map (with no PSEUDO_TABLE_BITS anymore).

◆ m_query_blocks_to_materialize

Mem_root_array<MaterializePathParameters::QueryBlock> Query_expression::m_query_blocks_to_materialize

private

If there is an unfinished materialization (see optimize()), contains one element for each query block in this query expression.

◆ m_query_result

Query_result* Query_expression::m_query_result

private

Object to which the result for this query expression is sent.

Not used if we materialize directly into a parent query expression's result table (see optimize()).

◆ m_query_term

Query_term* Query_expression::m_query_term {nullptr}

private

◆ m_reject_multiple_rows

bool Query_expression::m_reject_multiple_rows {false}

This query expression represents a scalar subquery and we need a run-time check that the cardinality doesn't exceed 1.

◆ m_root_access_path

AccessPath* Query_expression::m_root_access_path = nullptr

private

◆ m_root_iterator

unique_ptr_destroy_only<RowIterator> Query_expression::m_root_iterator

private

An iterator you can read from to get all records for this query.

May be nullptr even after create_access_paths(), or in the case of an unfinished materialization (see optimize()).

◆ m_with_clause

PT_with_clause* Query_expression::m_with_clause

The WITH clause which is the first part of this query expression.

NULL if none.

◆ master

Query_block* Query_expression::master

private

The query block wherein this query expression is contained, NULL if the query block is the outer-most one.

◆ next

Query_expression* Query_expression::next

private

Intrusive double-linked list of all query expressions immediately contained within the same query block.

◆ offset_limit_cnt

ha_rows Query_expression::offset_limit_cnt

◆ optimized

bool Query_expression::optimized

private

All query blocks in query expression are optimized.

◆ prepared

bool Query_expression::prepared

private

All query blocks in query expression are prepared.

◆ prev

Query_expression** Query_expression::prev

private

◆ select_limit_cnt

ha_rows Query_expression::select_limit_cnt

◆ send_records

ha_rows Query_expression::send_records

◆ slave

Query_block* Query_expression::slave

private

The first query block in this query expression.

◆ types

mem_root_deque<Item *> Query_expression::types

private

◆ uncacheable

uint8 Query_expression::uncacheable

result of this query can't be cached, bit field, can be : UNCACHEABLE_DEPENDENT UNCACHEABLE_RAND UNCACHEABLE_SIDEEFFECT

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

Public Types

Public Member Functions

Public Attributes

Private Member Functions

Private Attributes

Friends

Detailed Description

Member Enumeration Documentation

◆ enum_clean_state

Constructor & Destructor Documentation

◆ Query_expression()

Member Function Documentation

◆ accept()

◆ accumulate_used_tables()

◆ assert_not_fully_clean()

◆ can_materialize_directly_into_result()

◆ change_query_result()

◆ change_to_access_path_without_in2exists()

◆ check_materialized_derived_query_blocks()

◆ cleanup()

◆ clear_correlated_query_blocks()

◆ clear_execution()

◆ clear_root_access_path()

◆ ClearForExecution()

◆ create_access_paths()

◆ create_post_processing_block()

◆ destroy()

◆ exclude_level()

◆ exclude_tree()

◆ execute()

◆ ExecuteIteratorQuery()

◆ explain()

◆ explain_query_term()

◆ finalize()

◆ find_blocks_query_term()

◆ first_query_block()

◆ force_create_iterators()

◆ get_explain_marker()

◆ get_field_list()

◆ get_unit_column_types()

◆ global_parameters()

◆ has_any_limit()

◆ has_top_level_distinct()

◆ include_down()

◆ invalidate()

◆ is_executed()

◆ is_leaf_block()

◆ is_mergeable()

◆ is_optimized()

◆ is_prepared()

◆ is_recursive()

◆ is_simple()

◆ last_distinct()

◆ merge_heuristic()

◆ next_query_expression()

◆ non_simple_result_query_block()

◆ num_visible_fields()

◆ optimize()

◆ outer_query_block()

◆ place()

◆ prepare()

◆ prepare_query_term()

◆ print()

◆ query_result()

◆ query_term()

◆ query_terms()

◆ release_query_blocks_to_materialize()

◆ release_root_iterator()

◆ renumber_selects()

◆ reset_executed()

◆ restore_cmd_properties()

◆ root_access_path()

◆ root_iterator()

◆ save_cmd_properties()

◆ set_executed()

◆ set_explain_marker()

◆ set_explain_marker_from()

◆ set_limit()

◆ set_operation()

◆ set_optimized()