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Formerly we only applied extended statistics to an OR clause as part of the clauselist_selectivity() code path for an OR clause appearing in an implicitly-ANDed list of clauses. This meant that it could only use extended statistics if all sub-clauses of the OR clause were covered by a single extended statistics object. Instead, teach clause_selectivity() how to apply extended statistics to an OR clause by handling its ORed list of sub-clauses in a similar manner to an implicitly-ANDed list of sub-clauses, but with different combination rules. This allows one or more extended statistics objects to be used to estimate all or part of the list of sub-clauses. Any remaining sub-clauses are then treated as if they are independent. Additionally, to avoid double-application of extended statistics, this introduces "extended" versions of clause_selectivity() and clauselist_selectivity(), which include an option to ignore extended statistics. This replaces the old clauselist_selectivity_simple() function which failed to completely ignore extended statistics when called from the extended statistics code. A known limitation of the current infrastructure is that an AND clause under an OR clause is not treated as compatible with extended statistics (because we don't build RestrictInfos for such sub-AND clauses). Thus, for example, "(a=1 AND b=1) OR (a=2 AND b=2)" will currently be treated as two independent AND clauses (each of which may be estimated using extended statistics), but extended statistics will not currently be used to account for any possible overlap between those clauses. Improving that is left as a task for the future. Original patch by Tomas Vondra, with additional improvements by me. Discussion: https://postgr.es/m/20200113230008.g67iyk4cs3xbnjju@development
197 lines
6.6 KiB
C
197 lines
6.6 KiB
C
/*-------------------------------------------------------------------------
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*
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* optimizer.h
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* External API for the Postgres planner.
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*
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* This header is meant to define everything that the core planner
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* exposes for use by non-planner modules.
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*
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* Note that there are files outside src/backend/optimizer/ that are
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* considered planner modules, because they're too much in bed with
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* planner operations to be treated otherwise. FDW planning code is an
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* example. For the most part, however, code outside the core planner
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* should not need to include any optimizer/ header except this one.
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*
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* Portions Copyright (c) 1996-2020, 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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* src/include/optimizer/optimizer.h
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*
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*-------------------------------------------------------------------------
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*/
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#ifndef OPTIMIZER_H
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#define OPTIMIZER_H
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#include "nodes/parsenodes.h"
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/*
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* We don't want to include nodes/pathnodes.h here, because non-planner
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* code should generally treat PlannerInfo as an opaque typedef.
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* But we'd like such code to use that typedef name, so define the
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* typedef either here or in pathnodes.h, whichever is read first.
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*/
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#ifndef HAVE_PLANNERINFO_TYPEDEF
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typedef struct PlannerInfo PlannerInfo;
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#define HAVE_PLANNERINFO_TYPEDEF 1
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#endif
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/* Likewise for IndexOptInfo and SpecialJoinInfo. */
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#ifndef HAVE_INDEXOPTINFO_TYPEDEF
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typedef struct IndexOptInfo IndexOptInfo;
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#define HAVE_INDEXOPTINFO_TYPEDEF 1
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#endif
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#ifndef HAVE_SPECIALJOININFO_TYPEDEF
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typedef struct SpecialJoinInfo SpecialJoinInfo;
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#define HAVE_SPECIALJOININFO_TYPEDEF 1
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#endif
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/* It also seems best not to include plannodes.h, params.h, or htup.h here */
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struct PlannedStmt;
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struct ParamListInfoData;
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struct HeapTupleData;
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/* in path/clausesel.c: */
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extern Selectivity clause_selectivity(PlannerInfo *root,
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Node *clause,
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int varRelid,
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JoinType jointype,
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SpecialJoinInfo *sjinfo);
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extern Selectivity clause_selectivity_ext(PlannerInfo *root,
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Node *clause,
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int varRelid,
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JoinType jointype,
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SpecialJoinInfo *sjinfo,
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bool use_extended_stats);
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extern Selectivity clauselist_selectivity(PlannerInfo *root,
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List *clauses,
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int varRelid,
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JoinType jointype,
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SpecialJoinInfo *sjinfo);
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extern Selectivity clauselist_selectivity_ext(PlannerInfo *root,
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List *clauses,
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int varRelid,
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JoinType jointype,
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SpecialJoinInfo *sjinfo,
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bool use_extended_stats);
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/* in path/costsize.c: */
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/* widely used cost parameters */
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extern PGDLLIMPORT double seq_page_cost;
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extern PGDLLIMPORT double random_page_cost;
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extern PGDLLIMPORT double cpu_tuple_cost;
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extern PGDLLIMPORT double cpu_index_tuple_cost;
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extern PGDLLIMPORT double cpu_operator_cost;
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extern PGDLLIMPORT double parallel_tuple_cost;
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extern PGDLLIMPORT double parallel_setup_cost;
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extern PGDLLIMPORT int effective_cache_size;
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extern double clamp_row_est(double nrows);
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/* in path/indxpath.c: */
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extern bool is_pseudo_constant_for_index(Node *expr, IndexOptInfo *index);
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/* in plan/planner.c: */
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/* possible values for force_parallel_mode */
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typedef enum
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{
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FORCE_PARALLEL_OFF,
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FORCE_PARALLEL_ON,
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FORCE_PARALLEL_REGRESS
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} ForceParallelMode;
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/* GUC parameters */
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extern int force_parallel_mode;
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extern bool parallel_leader_participation;
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extern struct PlannedStmt *planner(Query *parse, const char *query_string,
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int cursorOptions,
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struct ParamListInfoData *boundParams);
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extern Expr *expression_planner(Expr *expr);
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extern Expr *expression_planner_with_deps(Expr *expr,
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List **relationOids,
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List **invalItems);
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extern bool plan_cluster_use_sort(Oid tableOid, Oid indexOid);
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extern int plan_create_index_workers(Oid tableOid, Oid indexOid);
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/* in plan/setrefs.c: */
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extern void extract_query_dependencies(Node *query,
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List **relationOids,
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List **invalItems,
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bool *hasRowSecurity);
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/* in prep/prepqual.c: */
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extern Node *negate_clause(Node *node);
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extern Expr *canonicalize_qual(Expr *qual, bool is_check);
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/* in util/clauses.c: */
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extern bool contain_mutable_functions(Node *clause);
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extern bool contain_volatile_functions(Node *clause);
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extern bool contain_volatile_functions_not_nextval(Node *clause);
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extern Node *eval_const_expressions(PlannerInfo *root, Node *node);
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extern Node *estimate_expression_value(PlannerInfo *root, Node *node);
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extern Expr *evaluate_expr(Expr *expr, Oid result_type, int32 result_typmod,
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Oid result_collation);
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extern List *expand_function_arguments(List *args, Oid result_type,
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struct HeapTupleData *func_tuple);
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/* in util/predtest.c: */
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extern bool predicate_implied_by(List *predicate_list, List *clause_list,
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bool weak);
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extern bool predicate_refuted_by(List *predicate_list, List *clause_list,
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bool weak);
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/* in util/tlist.c: */
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extern int count_nonjunk_tlist_entries(List *tlist);
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extern TargetEntry *get_sortgroupref_tle(Index sortref,
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List *targetList);
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extern TargetEntry *get_sortgroupclause_tle(SortGroupClause *sgClause,
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List *targetList);
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extern Node *get_sortgroupclause_expr(SortGroupClause *sgClause,
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List *targetList);
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extern List *get_sortgrouplist_exprs(List *sgClauses,
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List *targetList);
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extern SortGroupClause *get_sortgroupref_clause(Index sortref,
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List *clauses);
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extern SortGroupClause *get_sortgroupref_clause_noerr(Index sortref,
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List *clauses);
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/* in util/var.c: */
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/* Bits that can be OR'd into the flags argument of pull_var_clause() */
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#define PVC_INCLUDE_AGGREGATES 0x0001 /* include Aggrefs in output list */
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#define PVC_RECURSE_AGGREGATES 0x0002 /* recurse into Aggref arguments */
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#define PVC_INCLUDE_WINDOWFUNCS 0x0004 /* include WindowFuncs in output list */
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#define PVC_RECURSE_WINDOWFUNCS 0x0008 /* recurse into WindowFunc arguments */
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#define PVC_INCLUDE_PLACEHOLDERS 0x0010 /* include PlaceHolderVars in
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* output list */
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#define PVC_RECURSE_PLACEHOLDERS 0x0020 /* recurse into PlaceHolderVar
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* arguments */
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extern Bitmapset *pull_varnos(Node *node);
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extern Bitmapset *pull_varnos_of_level(Node *node, int levelsup);
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extern void pull_varattnos(Node *node, Index varno, Bitmapset **varattnos);
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extern List *pull_vars_of_level(Node *node, int levelsup);
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extern bool contain_var_clause(Node *node);
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extern bool contain_vars_of_level(Node *node, int levelsup);
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extern int locate_var_of_level(Node *node, int levelsup);
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extern List *pull_var_clause(Node *node, int flags);
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extern Node *flatten_join_alias_vars(Query *query, Node *node);
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#endif /* OPTIMIZER_H */
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