131 lines
4.7 KiB
C
131 lines
4.7 KiB
C
/*-------------------------------------------------------------------------
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*
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* statistics.h
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* Extended statistics and selectivity estimation functions.
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*
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* Portions Copyright (c) 1996-2024, 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/statistics/statistics.h
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*
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*-------------------------------------------------------------------------
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*/
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#ifndef STATISTICS_H
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#define STATISTICS_H
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#include "commands/vacuum.h"
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#include "nodes/pathnodes.h"
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#define STATS_MAX_DIMENSIONS 8 /* max number of attributes */
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/* Multivariate distinct coefficients */
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#define STATS_NDISTINCT_MAGIC 0xA352BFA4 /* struct identifier */
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#define STATS_NDISTINCT_TYPE_BASIC 1 /* struct version */
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/* MVNDistinctItem represents a single combination of columns */
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typedef struct MVNDistinctItem
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{
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double ndistinct; /* ndistinct value for this combination */
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int nattributes; /* number of attributes */
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AttrNumber *attributes; /* attribute numbers */
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} MVNDistinctItem;
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/* A MVNDistinct object, comprising all possible combinations of columns */
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typedef struct MVNDistinct
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{
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uint32 magic; /* magic constant marker */
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uint32 type; /* type of ndistinct (BASIC) */
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uint32 nitems; /* number of items in the statistic */
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MVNDistinctItem items[FLEXIBLE_ARRAY_MEMBER];
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} MVNDistinct;
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/* Multivariate functional dependencies */
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#define STATS_DEPS_MAGIC 0xB4549A2C /* marks serialized bytea */
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#define STATS_DEPS_TYPE_BASIC 1 /* basic dependencies type */
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/*
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* Functional dependencies, tracking column-level relationships (values
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* in one column determine values in another one).
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*/
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typedef struct MVDependency
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{
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double degree; /* degree of validity (0-1) */
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AttrNumber nattributes; /* number of attributes */
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AttrNumber attributes[FLEXIBLE_ARRAY_MEMBER]; /* attribute numbers */
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} MVDependency;
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typedef struct MVDependencies
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{
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uint32 magic; /* magic constant marker */
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uint32 type; /* type of MV Dependencies (BASIC) */
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uint32 ndeps; /* number of dependencies */
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MVDependency *deps[FLEXIBLE_ARRAY_MEMBER]; /* dependencies */
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} MVDependencies;
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/* used to flag stats serialized to bytea */
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#define STATS_MCV_MAGIC 0xE1A651C2 /* marks serialized bytea */
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#define STATS_MCV_TYPE_BASIC 1 /* basic MCV list type */
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/* max items in MCV list */
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#define STATS_MCVLIST_MAX_ITEMS MAX_STATISTICS_TARGET
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/*
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* Multivariate MCV (most-common value) lists
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*
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* A straightforward extension of MCV items - i.e. a list (array) of
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* combinations of attribute values, together with a frequency and null flags.
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*/
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typedef struct MCVItem
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{
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double frequency; /* frequency of this combination */
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double base_frequency; /* frequency if independent */
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bool *isnull; /* NULL flags */
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Datum *values; /* item values */
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} MCVItem;
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/* multivariate MCV list - essentially an array of MCV items */
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typedef struct MCVList
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{
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uint32 magic; /* magic constant marker */
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uint32 type; /* type of MCV list (BASIC) */
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uint32 nitems; /* number of MCV items in the array */
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AttrNumber ndimensions; /* number of dimensions */
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Oid types[STATS_MAX_DIMENSIONS]; /* OIDs of data types */
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MCVItem items[FLEXIBLE_ARRAY_MEMBER]; /* array of MCV items */
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} MCVList;
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extern MVNDistinct *statext_ndistinct_load(Oid mvoid, bool inh);
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extern MVDependencies *statext_dependencies_load(Oid mvoid, bool inh);
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extern MCVList *statext_mcv_load(Oid mvoid, bool inh);
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extern void BuildRelationExtStatistics(Relation onerel, bool inh, double totalrows,
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int numrows, HeapTuple *rows,
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int natts, VacAttrStats **vacattrstats);
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extern int ComputeExtStatisticsRows(Relation onerel,
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int natts, VacAttrStats **vacattrstats);
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extern bool statext_is_kind_built(HeapTuple htup, char type);
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extern Selectivity dependencies_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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RelOptInfo *rel,
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Bitmapset **estimatedclauses);
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extern Selectivity statext_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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RelOptInfo *rel,
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Bitmapset **estimatedclauses,
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bool is_or);
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extern bool has_stats_of_kind(List *stats, char requiredkind);
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extern StatisticExtInfo *choose_best_statistics(List *stats, char requiredkind,
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bool inh,
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Bitmapset **clause_attnums,
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List **clause_exprs,
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int nclauses);
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extern HeapTuple statext_expressions_load(Oid stxoid, bool inh, int idx);
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#endif /* STATISTICS_H */
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