mirror of
https://github.com/postgres/postgres.git
synced 2026-02-17 09:42:54 -05:00
0452b461bc
When evaluating a query with a multi-column GROUP BY clause, we can minimize sort operations or avoid them if we synchronize the order of GROUP BY clauses with the ORDER BY sort clause or sort order, which comes from the underlying query tree. Grouping does not imply any ordering, so we can compare the keys in arbitrary order, and a Hash Agg leverages this. But for Group Agg, we simply compared keys in the order specified in the query. This commit explores alternative ordering of the keys, trying to find a cheaper one. The ordering of group keys may interact with other parts of the query, some of which may not be known while planning the grouping. For example, there may be an explicit ORDER BY clause or some other ordering-dependent operation higher up in the query, and using the same ordering may allow using either incremental sort or even eliminating the sort entirely. The patch always keeps the ordering specified in the query, assuming the user might have additional insights. This introduces a new GUC enable_group_by_reordering so that the optimization may be disabled if needed. Discussion: https://postgr.es/m/7c79e6a5-8597-74e8-0671-1c39d124c9d6%40sigaev.ru Author: Andrei Lepikhov, Teodor Sigaev Reviewed-by: Tomas Vondra, Claudio Freire, Gavin Flower, Dmitry Dolgov Reviewed-by: Robert Haas, Pavel Borisov, David Rowley, Zhihong Yu Reviewed-by: Tom Lane, Alexander Korotkov, Richard Guo, Alena Rybakina
267 lines
10 KiB
C
267 lines
10 KiB
C
/*-------------------------------------------------------------------------
|
|
*
|
|
* paths.h
|
|
* prototypes for various files in optimizer/path
|
|
*
|
|
*
|
|
* Portions Copyright (c) 1996-2024, PostgreSQL Global Development Group
|
|
* Portions Copyright (c) 1994, Regents of the University of California
|
|
*
|
|
* src/include/optimizer/paths.h
|
|
*
|
|
*-------------------------------------------------------------------------
|
|
*/
|
|
#ifndef PATHS_H
|
|
#define PATHS_H
|
|
|
|
#include "nodes/pathnodes.h"
|
|
|
|
|
|
/*
|
|
* allpaths.c
|
|
*/
|
|
extern PGDLLIMPORT bool enable_geqo;
|
|
extern PGDLLIMPORT int geqo_threshold;
|
|
extern PGDLLIMPORT int min_parallel_table_scan_size;
|
|
extern PGDLLIMPORT int min_parallel_index_scan_size;
|
|
extern PGDLLIMPORT bool enable_group_by_reordering;
|
|
|
|
/* Hook for plugins to get control in set_rel_pathlist() */
|
|
typedef void (*set_rel_pathlist_hook_type) (PlannerInfo *root,
|
|
RelOptInfo *rel,
|
|
Index rti,
|
|
RangeTblEntry *rte);
|
|
extern PGDLLIMPORT set_rel_pathlist_hook_type set_rel_pathlist_hook;
|
|
|
|
/* Hook for plugins to get control in add_paths_to_joinrel() */
|
|
typedef void (*set_join_pathlist_hook_type) (PlannerInfo *root,
|
|
RelOptInfo *joinrel,
|
|
RelOptInfo *outerrel,
|
|
RelOptInfo *innerrel,
|
|
JoinType jointype,
|
|
JoinPathExtraData *extra);
|
|
extern PGDLLIMPORT set_join_pathlist_hook_type set_join_pathlist_hook;
|
|
|
|
/* Hook for plugins to replace standard_join_search() */
|
|
typedef RelOptInfo *(*join_search_hook_type) (PlannerInfo *root,
|
|
int levels_needed,
|
|
List *initial_rels);
|
|
extern PGDLLIMPORT join_search_hook_type join_search_hook;
|
|
|
|
|
|
extern RelOptInfo *make_one_rel(PlannerInfo *root, List *joinlist);
|
|
extern RelOptInfo *standard_join_search(PlannerInfo *root, int levels_needed,
|
|
List *initial_rels);
|
|
|
|
extern void generate_gather_paths(PlannerInfo *root, RelOptInfo *rel,
|
|
bool override_rows);
|
|
extern void generate_useful_gather_paths(PlannerInfo *root, RelOptInfo *rel,
|
|
bool override_rows);
|
|
extern int compute_parallel_worker(RelOptInfo *rel, double heap_pages,
|
|
double index_pages, int max_workers);
|
|
extern void create_partial_bitmap_paths(PlannerInfo *root, RelOptInfo *rel,
|
|
Path *bitmapqual);
|
|
extern void generate_partitionwise_join_paths(PlannerInfo *root,
|
|
RelOptInfo *rel);
|
|
|
|
/*
|
|
* indxpath.c
|
|
* routines to generate index paths
|
|
*/
|
|
extern void create_index_paths(PlannerInfo *root, RelOptInfo *rel);
|
|
extern bool relation_has_unique_index_for(PlannerInfo *root, RelOptInfo *rel,
|
|
List *restrictlist,
|
|
List *exprlist, List *oprlist);
|
|
extern bool relation_has_unique_index_ext(PlannerInfo *root, RelOptInfo *rel,
|
|
List *restrictlist, List *exprlist,
|
|
List *oprlist, List **extra_clauses);
|
|
extern bool indexcol_is_bool_constant_for_query(PlannerInfo *root,
|
|
IndexOptInfo *index,
|
|
int indexcol);
|
|
extern bool match_index_to_operand(Node *operand, int indexcol,
|
|
IndexOptInfo *index);
|
|
extern void check_index_predicates(PlannerInfo *root, RelOptInfo *rel);
|
|
|
|
/*
|
|
* tidpath.h
|
|
* routines to generate tid paths
|
|
*/
|
|
extern void create_tidscan_paths(PlannerInfo *root, RelOptInfo *rel);
|
|
|
|
/*
|
|
* joinpath.c
|
|
* routines to create join paths
|
|
*/
|
|
extern void add_paths_to_joinrel(PlannerInfo *root, RelOptInfo *joinrel,
|
|
RelOptInfo *outerrel, RelOptInfo *innerrel,
|
|
JoinType jointype, SpecialJoinInfo *sjinfo,
|
|
List *restrictlist);
|
|
|
|
/*
|
|
* joinrels.c
|
|
* routines to determine which relations to join
|
|
*/
|
|
extern void join_search_one_level(PlannerInfo *root, int level);
|
|
extern RelOptInfo *make_join_rel(PlannerInfo *root,
|
|
RelOptInfo *rel1, RelOptInfo *rel2);
|
|
extern Relids add_outer_joins_to_relids(PlannerInfo *root, Relids input_relids,
|
|
SpecialJoinInfo *sjinfo,
|
|
List **pushed_down_joins);
|
|
extern bool have_join_order_restriction(PlannerInfo *root,
|
|
RelOptInfo *rel1, RelOptInfo *rel2);
|
|
extern bool have_dangerous_phv(PlannerInfo *root,
|
|
Relids outer_relids, Relids inner_params);
|
|
extern void mark_dummy_rel(RelOptInfo *rel);
|
|
|
|
/*
|
|
* equivclass.c
|
|
* routines for managing EquivalenceClasses
|
|
*/
|
|
typedef bool (*ec_matches_callback_type) (PlannerInfo *root,
|
|
RelOptInfo *rel,
|
|
EquivalenceClass *ec,
|
|
EquivalenceMember *em,
|
|
void *arg);
|
|
|
|
extern bool process_equivalence(PlannerInfo *root,
|
|
RestrictInfo **p_restrictinfo,
|
|
JoinDomain *jdomain);
|
|
extern Expr *canonicalize_ec_expression(Expr *expr,
|
|
Oid req_type, Oid req_collation);
|
|
extern void reconsider_outer_join_clauses(PlannerInfo *root);
|
|
extern EquivalenceClass *get_eclass_for_sort_expr(PlannerInfo *root,
|
|
Expr *expr,
|
|
List *opfamilies,
|
|
Oid opcintype,
|
|
Oid collation,
|
|
Index sortref,
|
|
Relids rel,
|
|
bool create_it);
|
|
extern EquivalenceMember *find_ec_member_matching_expr(EquivalenceClass *ec,
|
|
Expr *expr,
|
|
Relids relids);
|
|
extern EquivalenceMember *find_computable_ec_member(PlannerInfo *root,
|
|
EquivalenceClass *ec,
|
|
List *exprs,
|
|
Relids relids,
|
|
bool require_parallel_safe);
|
|
extern bool relation_can_be_sorted_early(PlannerInfo *root, RelOptInfo *rel,
|
|
EquivalenceClass *ec,
|
|
bool require_parallel_safe);
|
|
extern void generate_base_implied_equalities(PlannerInfo *root);
|
|
extern List *generate_join_implied_equalities(PlannerInfo *root,
|
|
Relids join_relids,
|
|
Relids outer_relids,
|
|
RelOptInfo *inner_rel,
|
|
SpecialJoinInfo *sjinfo);
|
|
extern List *generate_join_implied_equalities_for_ecs(PlannerInfo *root,
|
|
List *eclasses,
|
|
Relids join_relids,
|
|
Relids outer_relids,
|
|
RelOptInfo *inner_rel);
|
|
extern bool exprs_known_equal(PlannerInfo *root, Node *item1, Node *item2);
|
|
extern EquivalenceClass *match_eclasses_to_foreign_key_col(PlannerInfo *root,
|
|
ForeignKeyOptInfo *fkinfo,
|
|
int colno);
|
|
extern RestrictInfo *find_derived_clause_for_ec_member(EquivalenceClass *ec,
|
|
EquivalenceMember *em);
|
|
extern void add_child_rel_equivalences(PlannerInfo *root,
|
|
AppendRelInfo *appinfo,
|
|
RelOptInfo *parent_rel,
|
|
RelOptInfo *child_rel);
|
|
extern void add_child_join_rel_equivalences(PlannerInfo *root,
|
|
int nappinfos,
|
|
AppendRelInfo **appinfos,
|
|
RelOptInfo *parent_joinrel,
|
|
RelOptInfo *child_joinrel);
|
|
extern List *generate_implied_equalities_for_column(PlannerInfo *root,
|
|
RelOptInfo *rel,
|
|
ec_matches_callback_type callback,
|
|
void *callback_arg,
|
|
Relids prohibited_rels);
|
|
extern bool have_relevant_eclass_joinclause(PlannerInfo *root,
|
|
RelOptInfo *rel1, RelOptInfo *rel2);
|
|
extern bool has_relevant_eclass_joinclause(PlannerInfo *root,
|
|
RelOptInfo *rel1);
|
|
extern bool eclass_useful_for_merging(PlannerInfo *root,
|
|
EquivalenceClass *eclass,
|
|
RelOptInfo *rel);
|
|
extern bool is_redundant_derived_clause(RestrictInfo *rinfo, List *clauselist);
|
|
extern bool is_redundant_with_indexclauses(RestrictInfo *rinfo,
|
|
List *indexclauses);
|
|
|
|
/*
|
|
* pathkeys.c
|
|
* utilities for matching and building path keys
|
|
*/
|
|
typedef enum
|
|
{
|
|
PATHKEYS_EQUAL, /* pathkeys are identical */
|
|
PATHKEYS_BETTER1, /* pathkey 1 is a superset of pathkey 2 */
|
|
PATHKEYS_BETTER2, /* vice versa */
|
|
PATHKEYS_DIFFERENT, /* neither pathkey includes the other */
|
|
} PathKeysComparison;
|
|
|
|
extern PathKeysComparison compare_pathkeys(List *keys1, List *keys2);
|
|
extern bool pathkeys_contained_in(List *keys1, List *keys2);
|
|
extern bool pathkeys_count_contained_in(List *keys1, List *keys2, int *n_common);
|
|
extern List *get_useful_group_keys_orderings(PlannerInfo *root, Path *path);
|
|
extern Path *get_cheapest_path_for_pathkeys(List *paths, List *pathkeys,
|
|
Relids required_outer,
|
|
CostSelector cost_criterion,
|
|
bool require_parallel_safe);
|
|
extern Path *get_cheapest_fractional_path_for_pathkeys(List *paths,
|
|
List *pathkeys,
|
|
Relids required_outer,
|
|
double fraction);
|
|
extern Path *get_cheapest_parallel_safe_total_inner(List *paths);
|
|
extern List *build_index_pathkeys(PlannerInfo *root, IndexOptInfo *index,
|
|
ScanDirection scandir);
|
|
extern List *build_partition_pathkeys(PlannerInfo *root, RelOptInfo *partrel,
|
|
ScanDirection scandir, bool *partialkeys);
|
|
extern List *build_expression_pathkey(PlannerInfo *root, Expr *expr,
|
|
Oid opno,
|
|
Relids rel, bool create_it);
|
|
extern List *convert_subquery_pathkeys(PlannerInfo *root, RelOptInfo *rel,
|
|
List *subquery_pathkeys,
|
|
List *subquery_tlist);
|
|
extern List *build_join_pathkeys(PlannerInfo *root,
|
|
RelOptInfo *joinrel,
|
|
JoinType jointype,
|
|
List *outer_pathkeys);
|
|
extern List *make_pathkeys_for_sortclauses(PlannerInfo *root,
|
|
List *sortclauses,
|
|
List *tlist);
|
|
extern List *make_pathkeys_for_sortclauses_extended(PlannerInfo *root,
|
|
List **sortclauses,
|
|
List *tlist,
|
|
bool remove_redundant,
|
|
bool *sortable);
|
|
extern void initialize_mergeclause_eclasses(PlannerInfo *root,
|
|
RestrictInfo *restrictinfo);
|
|
extern void update_mergeclause_eclasses(PlannerInfo *root,
|
|
RestrictInfo *restrictinfo);
|
|
extern List *find_mergeclauses_for_outer_pathkeys(PlannerInfo *root,
|
|
List *pathkeys,
|
|
List *restrictinfos);
|
|
extern List *select_outer_pathkeys_for_merge(PlannerInfo *root,
|
|
List *mergeclauses,
|
|
RelOptInfo *joinrel);
|
|
extern List *make_inner_pathkeys_for_merge(PlannerInfo *root,
|
|
List *mergeclauses,
|
|
List *outer_pathkeys);
|
|
extern List *trim_mergeclauses_for_inner_pathkeys(PlannerInfo *root,
|
|
List *mergeclauses,
|
|
List *pathkeys);
|
|
extern List *truncate_useless_pathkeys(PlannerInfo *root,
|
|
RelOptInfo *rel,
|
|
List *pathkeys);
|
|
extern bool has_useful_pathkeys(PlannerInfo *root, RelOptInfo *rel);
|
|
extern List *append_pathkeys(List *target, List *source);
|
|
extern PathKey *make_canonical_pathkey(PlannerInfo *root,
|
|
EquivalenceClass *eclass, Oid opfamily,
|
|
int strategy, bool nulls_first);
|
|
extern void add_paths_to_append_rel(PlannerInfo *root, RelOptInfo *rel,
|
|
List *live_childrels);
|
|
|
|
#endif /* PATHS_H */
|