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/*-------------------------------------------------------------------------
*
* statistics.h
* Extended statistics and selectivity estimation functions.
*
* Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* src/include/statistics/statistics.h
*
*-------------------------------------------------------------------------
*/
#ifndef STATISTICS_H
#define STATISTICS_H
#include "commands/vacuum.h"
#include "nodes/pathnodes.h"
#define STATS_MAX_DIMENSIONS 8 /* max number of attributes */
/* Multivariate distinct coefficients */
#define STATS_NDISTINCT_MAGIC 0xA352BFA4 /* struct identifier */
#define STATS_NDISTINCT_TYPE_BASIC 1 /* struct version */
/* MVNDistinctItem represents a single combination of columns */
typedef struct MVNDistinctItem
{
double ndistinct; /* ndistinct value for this combination */
Bitmapset *attrs; /* attr numbers of items */
} MVNDistinctItem;
/* A MVNDistinct object, comprising all possible combinations of columns */
typedef struct MVNDistinct
{
uint32 magic; /* magic constant marker */
uint32 type; /* type of ndistinct (BASIC) */
uint32 nitems; /* number of items in the statistic */
MVNDistinctItem items[FLEXIBLE_ARRAY_MEMBER];
} MVNDistinct;
/* Multivariate functional dependencies */
#define STATS_DEPS_MAGIC 0xB4549A2C /* marks serialized bytea */
#define STATS_DEPS_TYPE_BASIC 1 /* basic dependencies type */
/*
* Functional dependencies, tracking column-level relationships (values
* in one column determine values in another one).
*/
typedef struct MVDependency
{
double degree; /* degree of validity (0-1) */
AttrNumber nattributes; /* number of attributes */
AttrNumber attributes[FLEXIBLE_ARRAY_MEMBER]; /* attribute numbers */
} MVDependency;
typedef struct MVDependencies
{
uint32 magic; /* magic constant marker */
uint32 type; /* type of MV Dependencies (BASIC) */
uint32 ndeps; /* number of dependencies */
MVDependency *deps[FLEXIBLE_ARRAY_MEMBER]; /* dependencies */
} MVDependencies;
/* used to flag stats serialized to bytea */
#define STATS_MCV_MAGIC 0xE1A651C2 /* marks serialized bytea */
#define STATS_MCV_TYPE_BASIC 1 /* basic MCV list type */
/* max items in MCV list (should be equal to max default_statistics_target) */
#define STATS_MCVLIST_MAX_ITEMS 10000
/*
* Multivariate MCV (most-common value) lists
*
* A straightforward extension of MCV items - i.e. a list (array) of
* combinations of attribute values, together with a frequency and null flags.
*/
typedef struct MCVItem
{
double frequency; /* frequency of this combination */
double base_frequency; /* frequency if independent */
bool *isnull; /* NULL flags */
Datum *values; /* item values */
} MCVItem;
/* multivariate MCV list - essentially an array of MCV items */
typedef struct MCVList
{
uint32 magic; /* magic constant marker */
uint32 type; /* type of MCV list (BASIC) */
uint32 nitems; /* number of MCV items in the array */
AttrNumber ndimensions; /* number of dimensions */
Oid types[STATS_MAX_DIMENSIONS]; /* OIDs of data types */
MCVItem items[FLEXIBLE_ARRAY_MEMBER]; /* array of MCV items */
} MCVList;
extern MVNDistinct *statext_ndistinct_load(Oid mvoid);
extern MVDependencies *statext_dependencies_load(Oid mvoid);
extern MCVList *statext_mcv_load(Oid mvoid);
extern void BuildRelationExtStatistics(Relation onerel, double totalrows,
int numrows, HeapTuple *rows,
int natts, VacAttrStats **vacattrstats);
extern int ComputeExtStatisticsRows(Relation onerel,
int natts, VacAttrStats **stats);
extern bool statext_is_kind_built(HeapTuple htup, char kind);
extern Selectivity dependencies_clauselist_selectivity(PlannerInfo *root,
List *clauses,
int varRelid,
JoinType jointype,
SpecialJoinInfo *sjinfo,
RelOptInfo *rel,
Bitmapset **estimatedclauses);
extern Selectivity statext_clauselist_selectivity(PlannerInfo *root,
List *clauses,
int varRelid,
JoinType jointype,
SpecialJoinInfo *sjinfo,
RelOptInfo *rel,
Bitmapset **estimatedclauses);
extern bool has_stats_of_kind(List *stats, char requiredkind);
extern StatisticExtInfo *choose_best_statistics(List *stats, char requiredkind,
Bitmapset **clause_attnums,
int nclauses);
#endif /* STATISTICS_H */
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