This struct implements a builder pattern for creating paths that do DISTINCT (sort with duplicate removal) and adding them as parent of the current candidate paths (except for candidate paths that do DISTINCT already). More...

Public Member Functions
AccessPathArray	ApplyDistinct () const
	Create new root paths as needed to do DISTINCT. More...

Public Attributes
THD *	thd
	The current thread. More...

const CostingReceiver *	receiver
	The planning context. More...

const LogicalOrderings *	orderings
	The set of interesting orders. More...

bool	aggregation_is_unordered
	Aggregation (GROUP BY and DISTINCT) do not require ordered inputs and create unordered outputs (. More...

int	order_by_ordering_idx
	The order by which the result should be ordered (or -1 if none). More...

int	distinct_ordering_idx
	The order by which the result should be grouped. More...

const Mem_root_array< SortAheadOrdering > *	sort_ahead_orderings
	The orders we may sort by. More...

FunctionalDependencySet	fd_set
	The functional dependencies that apply here. More...

Query_block *	query_block
	The enclosing query block. More...

bool	need_rowid
	True if we need rowids. More...

const AccessPathArray *	root_candidates
	The candidate paths. More...

Private Member Functions
std::optional< LogicalOrderings::StateIndex >	DistinctOrderingState (size_t grouping_size, const SortAheadOrdering &sort_ahead_ordering) const
	Check if 'sort_ahead_ordering' is a useful order to sort by. More...

AccessPath	MakeSortPathForDistinct (AccessPath *root_path, int ordering_idx, LogicalOrderings::StateIndex ordering_state, double output_rows) const
	Create a sort part on top of 'root_path'. More...

void	ProposeDistinctPaths (const Bounds_checked_array< Item * > group_items, AccessPath root_path, double output_rows, AccessPathArray new_root_candidates) const
	Add a parent path to root_path to ensure that the output is grouped (by distinct_ordering_idx) if this is not the case already. More...

Detailed Description

This struct implements a builder pattern for creating paths that do DISTINCT (sort with duplicate removal) and adding them as parent of the current candidate paths (except for candidate paths that do DISTINCT already).

The struct eliminates overly long parameter lists, and makes it easy to divide the task into a set of simpler functions.

Member Function Documentation

◆ ApplyDistinct()

AccessPathArray anonymous_namespace{join_optimizer.cc}::ApplyDistinctParameters::ApplyDistinct ( ) const

Create new root paths as needed to do DISTINCT.

Returns: The new root paths.

◆ DistinctOrderingState()

std::optional< LogicalOrderings::StateIndex > anonymous_namespace{join_optimizer.cc}::ApplyDistinctParameters::DistinctOrderingState	(	size_t	grouping_size,
		const SortAheadOrdering &	sort_ahead_ordering
	)		const

private

Check if 'sort_ahead_ordering' is a useful order to sort by.

Parameters

grouping_size	The size of the DISTINCT projection.
sort_ahead_ordering	The candidate ordering.

Returns: The ordering state if we should sort by this order, and an empty object otherwise.

◆ MakeSortPathForDistinct()

AccessPath anonymous_namespace{join_optimizer.cc}::ApplyDistinctParameters::MakeSortPathForDistinct	(	AccessPath *	root_path,
		int	ordering_idx,
		LogicalOrderings::StateIndex	ordering_state,
		double	output_rows
	)		const

private

Create a sort part on top of 'root_path'.

Parameters

root_path	The path that needs sorting.
ordering_idx	The order to sort by.
ordering_state	The ordering state of the new path.
output_rows	The number of (distinct) output row from the new path.

Returns: The sort path.

◆ ProposeDistinctPaths()

void anonymous_namespace{join_optimizer.cc}::ApplyDistinctParameters::ProposeDistinctPaths	(	const Bounds_checked_array< Item * >	group_items,
		AccessPath *	root_path,
		double	output_rows,
		AccessPathArray *	new_root_candidates
	)		const

private

Add a parent path to root_path to ensure that the output is grouped (by distinct_ordering_idx) if this is not the case already.

Note that we may add multiple alternative parent paths if there are several relevant sort-ahead orders.

Parameters

group_items	This items we group on.
root_path	The input path.
output_rows	The number of (distinct) output rows.
new_root_candidates	We add parent paths to this.

Member Data Documentation

◆ aggregation_is_unordered

bool anonymous_namespace{join_optimizer.cc}::ApplyDistinctParameters::aggregation_is_unordered

Aggregation (GROUP BY and DISTINCT) do not require ordered inputs and create unordered outputs (.

See also: SecondaryEngineFlag).

◆ distinct_ordering_idx

int anonymous_namespace{join_optimizer.cc}::ApplyDistinctParameters::distinct_ordering_idx

The order by which the result should be grouped.

◆ fd_set

FunctionalDependencySet anonymous_namespace{join_optimizer.cc}::ApplyDistinctParameters::fd_set

The functional dependencies that apply here.

◆ need_rowid

bool anonymous_namespace{join_optimizer.cc}::ApplyDistinctParameters::need_rowid

True if we need rowids.

◆ order_by_ordering_idx

int anonymous_namespace{join_optimizer.cc}::ApplyDistinctParameters::order_by_ordering_idx

The order by which the result should be ordered (or -1 if none).

◆ orderings

const LogicalOrderings* anonymous_namespace{join_optimizer.cc}::ApplyDistinctParameters::orderings

The set of interesting orders.

◆ query_block

Query_block* anonymous_namespace{join_optimizer.cc}::ApplyDistinctParameters::query_block

The enclosing query block.

◆ receiver

const CostingReceiver* anonymous_namespace{join_optimizer.cc}::ApplyDistinctParameters::receiver

The planning context.

◆ root_candidates

const AccessPathArray* anonymous_namespace{join_optimizer.cc}::ApplyDistinctParameters::root_candidates

The candidate paths.

◆ sort_ahead_orderings

const Mem_root_array<SortAheadOrdering>* anonymous_namespace{join_optimizer.cc}::ApplyDistinctParameters::sort_ahead_orderings

The orders we may sort by.

◆ thd

THD* anonymous_namespace{join_optimizer.cc}::ApplyDistinctParameters::thd

The current thread.

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

sql/join_optimizer/join_optimizer.cc

Public Member Functions

Public Attributes

Private Member Functions

Detailed Description

Member Function Documentation

◆ ApplyDistinct()

◆ DistinctOrderingState()

◆ MakeSortPathForDistinct()

◆ ProposeDistinctPaths()

Member Data Documentation

◆ aggregation_is_unordered

◆ distinct_ordering_idx

◆ fd_set

◆ need_rowid

◆ order_by_ordering_idx

◆ orderings

◆ query_block

◆ receiver

◆ root_candidates

◆ sort_ahead_orderings

◆ thd