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107cbb2b90
cheapest-startup-cost innerjoin indexscans, and make joinpath.c consider both of these (when different) as the inside of a nestloop join. The original design was based on the assumption that indexscan paths always have negligible startup cost, and so total cost is the only important figure of merit; an assumption that's obviously broken by bitmap indexscans. This oversight could lead to choosing poor plans in cases where fast-start behavior is more important than total cost, such as LIMIT and IN queries. 8.1-vintage brain fade exposed by an example from Chuck D.
145 lines
4.8 KiB
C
145 lines
4.8 KiB
C
/*-------------------------------------------------------------------------
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*
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* paths.h
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* prototypes for various files in optimizer/path
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*
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*
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* Portions Copyright (c) 1996-2006, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* $PostgreSQL: pgsql/src/include/optimizer/paths.h,v 1.93.2.2 2007/05/22 01:40:42 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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#ifndef PATHS_H
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#define PATHS_H
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#include "nodes/relation.h"
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/*
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* allpaths.c
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*/
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extern bool enable_geqo;
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extern int geqo_threshold;
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extern RelOptInfo *make_one_rel(PlannerInfo *root, List *joinlist);
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#ifdef OPTIMIZER_DEBUG
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extern void debug_print_rel(PlannerInfo *root, RelOptInfo *rel);
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#endif
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/*
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* indxpath.c
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* routines to generate index paths
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*/
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typedef enum
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{
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/* Whether to use ScalarArrayOpExpr to build index qualifications */
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SAOP_FORBID, /* Do not use ScalarArrayOpExpr */
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SAOP_ALLOW, /* OK to use ScalarArrayOpExpr */
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SAOP_REQUIRE /* Require ScalarArrayOpExpr */
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} SaOpControl;
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extern void create_index_paths(PlannerInfo *root, RelOptInfo *rel);
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extern List *generate_bitmap_or_paths(PlannerInfo *root, RelOptInfo *rel,
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List *clauses, List *outer_clauses,
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RelOptInfo *outer_rel);
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extern void best_inner_indexscan(PlannerInfo *root, RelOptInfo *rel,
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RelOptInfo *outer_rel, JoinType jointype,
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Path **cheapest_startup, Path **cheapest_total);
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extern List *group_clauses_by_indexkey(IndexOptInfo *index,
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List *clauses, List *outer_clauses,
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Relids outer_relids,
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SaOpControl saop_control,
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bool *found_clause);
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extern bool match_index_to_operand(Node *operand, int indexcol,
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IndexOptInfo *index);
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extern List *expand_indexqual_conditions(IndexOptInfo *index,
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List *clausegroups);
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extern void check_partial_indexes(PlannerInfo *root, RelOptInfo *rel);
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extern List *flatten_clausegroups_list(List *clausegroups);
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/*
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* orindxpath.c
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* additional routines for indexable OR clauses
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*/
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extern bool create_or_index_quals(PlannerInfo *root, RelOptInfo *rel);
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/*
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* tidpath.h
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* routines to generate tid paths
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*/
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extern void create_tidscan_paths(PlannerInfo *root, RelOptInfo *rel);
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/*
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* joinpath.c
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* routines to create join paths
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*/
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extern void add_paths_to_joinrel(PlannerInfo *root, RelOptInfo *joinrel,
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RelOptInfo *outerrel,
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RelOptInfo *innerrel,
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JoinType jointype,
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List *restrictlist);
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/*
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* joinrels.c
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* routines to determine which relations to join
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*/
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extern List *make_rels_by_joins(PlannerInfo *root, int level, List **joinrels);
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extern RelOptInfo *make_join_rel(PlannerInfo *root,
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RelOptInfo *rel1, RelOptInfo *rel2);
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extern bool have_join_order_restriction(PlannerInfo *root,
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RelOptInfo *rel1, RelOptInfo *rel2);
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/*
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* pathkeys.c
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* utilities for matching and building path keys
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*/
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typedef enum
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{
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PATHKEYS_EQUAL, /* pathkeys are identical */
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PATHKEYS_BETTER1, /* pathkey 1 is a superset of pathkey 2 */
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PATHKEYS_BETTER2, /* vice versa */
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PATHKEYS_DIFFERENT /* neither pathkey includes the other */
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} PathKeysComparison;
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extern void add_equijoined_keys(PlannerInfo *root, RestrictInfo *restrictinfo);
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extern bool exprs_known_equal(PlannerInfo *root, Node *item1, Node *item2);
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extern void generate_implied_equalities(PlannerInfo *root);
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extern List *canonicalize_pathkeys(PlannerInfo *root, List *pathkeys);
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extern PathKeysComparison compare_pathkeys(List *keys1, List *keys2);
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extern bool pathkeys_contained_in(List *keys1, List *keys2);
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extern Path *get_cheapest_path_for_pathkeys(List *paths, List *pathkeys,
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CostSelector cost_criterion);
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extern Path *get_cheapest_fractional_path_for_pathkeys(List *paths,
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List *pathkeys,
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double fraction);
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extern List *build_index_pathkeys(PlannerInfo *root, IndexOptInfo *index,
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ScanDirection scandir, bool canonical);
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extern List *convert_subquery_pathkeys(PlannerInfo *root, RelOptInfo *rel,
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List *subquery_pathkeys);
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extern List *build_join_pathkeys(PlannerInfo *root,
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RelOptInfo *joinrel,
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JoinType jointype,
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List *outer_pathkeys);
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extern List *make_pathkeys_for_sortclauses(List *sortclauses,
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List *tlist);
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extern void cache_mergeclause_pathkeys(PlannerInfo *root,
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RestrictInfo *restrictinfo);
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extern List *find_mergeclauses_for_pathkeys(PlannerInfo *root,
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List *pathkeys,
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List *restrictinfos);
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extern List *make_pathkeys_for_mergeclauses(PlannerInfo *root,
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List *mergeclauses,
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RelOptInfo *rel);
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extern int pathkeys_useful_for_merging(PlannerInfo *root,
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RelOptInfo *rel,
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List *pathkeys);
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extern int pathkeys_useful_for_ordering(PlannerInfo *root, List *pathkeys);
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extern List *truncate_useless_pathkeys(PlannerInfo *root,
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RelOptInfo *rel,
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List *pathkeys);
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#endif /* PATHS_H */
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