build_interesting_orders.h File Reference

#include "sql/join_optimizer/interesting_orders.h"
#include "sql/join_optimizer/node_map.h"
#include <string>

Go to the source code of this file.

Classes
struct	SortAheadOrdering
struct	ActiveIndexInfo
struct	FullTextIndexInfo

Functions
void	BuildInterestingOrders (THD *thd, JoinHypergraph *graph, Query_block *query_block, LogicalOrderings *orderings, Mem_root_array< SortAheadOrdering > *sort_ahead_orderings, int *order_by_ordering_idx, int *group_by_ordering_idx, int *distinct_ordering_idx, Mem_root_array< ActiveIndexInfo > *active_indexes, Mem_root_array< FullTextIndexInfo > *fulltext_searches, std::string *trace)
	Build all structures we need for keeping track of interesting orders. More...
ORDER *	BuildSortAheadOrdering (THD *thd, const LogicalOrderings *orderings, Ordering ordering)
Ordering	ReduceFinalOrdering (THD *thd, const LogicalOrderings &orderings, int ordering_idx)
	Creates a reduced ordering for the ordering or grouping specified by "ordering_idx". More...

Function Documentation

BuildInterestingOrders()

void BuildInterestingOrders	(	THD *	thd,
		JoinHypergraph *	graph,
		Query_block *	query_block,
		LogicalOrderings *	orderings,
		Mem_root_array< SortAheadOrdering > *	sort_ahead_orderings,
		int *	order_by_ordering_idx,
		int *	group_by_ordering_idx,
		int *	distinct_ordering_idx,
		Mem_root_array< ActiveIndexInfo > *	active_indexes,
		Mem_root_array< FullTextIndexInfo > *	fulltext_searches,
		std::string *	trace
	)

Build all structures we need for keeping track of interesting orders.

We collect the actual relevant orderings (e.g. from ORDER BY) and any functional dependencies we can find, then ask LogicalOrderings to create its state machine (as defined in interesting_orders.h). The result is said state machine, a list of potential sort-ahead orderings, and a list of what indexes we can use to scan each table (including what orderings they yield, if they are interesting).

BuildSortAheadOrdering()

ORDER * BuildSortAheadOrdering	(	THD *	thd,
		const LogicalOrderings *	orderings,
		Ordering	ordering
	)

ReduceFinalOrdering()

Ordering ReduceFinalOrdering	(	THD *	thd,
		const LogicalOrderings &	orderings,
		int	ordering_idx
	)

Creates a reduced ordering for the ordering or grouping specified by "ordering_idx".

It is assumed that the ordering happens after all joins and filters, so that all functional dependencies are active. All parts of the ordering that are made redundant by functional dependencies, are removed.

The returned ordering may be empty if all elements are redundant. This happens if all elements are constants, or have predicates that ensure they are constant.