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/*-------------------------------------------------------------------------
*
* statistics.h
* Extended statistics and selectivity estimation functions.
*
* Portions Copyright (c) 1996-2017, 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"
#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 */
/* MVDistinctItem 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;
extern MVNDistinct *statext_ndistinct_load(Oid mvoid);
extern void BuildRelationExtStatistics(Relation onerel, double totalrows,
int numrows, HeapTuple *rows,
int natts, VacAttrStats **vacattrstats);
extern bool statext_is_kind_built(HeapTuple htup, char kind);
#endif /* STATISTICS_H */
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