/*-------------------------------------------------------------------------
 *
 * statistics.h
 *	  Extended statistics and selectivity estimation functions.
 *
 * Portions Copyright (c) 1996-2019, 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 */

/* MVDistinctItem represents a single combination of columns */
typedef struct MVNDistinctItem
{
	double		ndistinct;		/* ndistinct value for this combination */
	Bitmapset  *attrs;			/* attr numbers of items */
} MVNDistinctItem;

/* size of the struct, excluding attribute list */
#define SizeOfMVNDistinctItem \
	(offsetof(MVNDistinctItem, ndistinct) + sizeof(double))

/* 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;

/* size of the struct excluding the items array */
#define SizeOfMVNDistinct	(offsetof(MVNDistinct, nitems) + sizeof(uint32))


/* size of the struct excluding the items array */
#define SizeOfMVNDistinct	(offsetof(MVNDistinct, nitems) + sizeof(uint32))

#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;

/* size of the struct excluding the deps array */
#define SizeOfDependency \
	(offsetof(MVDependency, nattributes) + sizeof(AttrNumber))

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;

/* size of the struct excluding the deps array */
#define SizeOfDependencies	(offsetof(MVDependencies, ndeps) + sizeof(uint32))

extern MVNDistinct *statext_ndistinct_load(Oid mvoid);
extern MVDependencies *statext_dependencies_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);
extern Selectivity dependencies_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,
					   Bitmapset *attnums, char requiredkind);

#endif							/* STATISTICS_H */
