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/*-------------------------------------------------------------------------
*
* selfuncs.h
* Selectivity functions and index cost estimation functions for
* standard operators and index access methods.
*
*
* Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $PostgreSQL: pgsql/src/include/utils/selfuncs.h,v 1.43 2008/01/01 19:45:59 momjian Exp $
*
*-------------------------------------------------------------------------
*/
#ifndef SELFUNCS_H
#define SELFUNCS_H
#include "fmgr.h"
#include "access/htup.h"
#include "nodes/relation.h"
/*
* Note: the default selectivity estimates are not chosen entirely at random.
* We want them to be small enough to ensure that indexscans will be used if
* available, for typical table densities of ~100 tuples/page. Thus, for
* example, 0.01 is not quite small enough, since that makes it appear that
* nearly all pages will be hit anyway. Also, since we sometimes estimate
* eqsel as 1/num_distinct, we probably want DEFAULT_NUM_DISTINCT to equal
* 1/DEFAULT_EQ_SEL.
*/
/* default selectivity estimate for equalities such as "A = b" */
#define DEFAULT_EQ_SEL 0.005
/* default selectivity estimate for inequalities such as "A < b" */
#define DEFAULT_INEQ_SEL 0.3333333333333333
/* default selectivity estimate for range inequalities "A > b AND A < c" */
#define DEFAULT_RANGE_INEQ_SEL 0.005
/* default selectivity estimate for pattern-match operators such as LIKE */
#define DEFAULT_MATCH_SEL 0.005
/* default number of distinct values in a table */
#define DEFAULT_NUM_DISTINCT 200
/* default selectivity estimate for boolean and null test nodes */
#define DEFAULT_UNK_SEL 0.005
#define DEFAULT_NOT_UNK_SEL (1.0 - DEFAULT_UNK_SEL)
/*
* Clamp a computed probability estimate (which may suffer from roundoff or
* estimation errors) to valid range. Argument must be a float variable.
*/
#define CLAMP_PROBABILITY(p) \
do { \
if (p < 0.0) \
p = 0.0; \
else if (p > 1.0) \
p = 1.0; \
} while (0)
/* Return data from examine_variable and friends */
typedef struct
{
Node *var; /* the Var or expression tree */
RelOptInfo *rel; /* Relation, or NULL if not identifiable */
HeapTuple statsTuple; /* pg_statistic tuple, or NULL if none */
/* NB: if statsTuple!=NULL, it must be freed when caller is done */
Oid vartype; /* exposed type of expression */
Oid atttype; /* type to pass to get_attstatsslot */
int32 atttypmod; /* typmod to pass to get_attstatsslot */
bool isunique; /* true if matched to a unique index */
} VariableStatData;
#define ReleaseVariableStats(vardata) \
do { \
if (HeapTupleIsValid((vardata).statsTuple)) \
ReleaseSysCache((vardata).statsTuple); \
} while(0)
typedef enum
{
Pattern_Type_Like, Pattern_Type_Like_IC,
Pattern_Type_Regex, Pattern_Type_Regex_IC
} Pattern_Type;
typedef enum
{
Pattern_Prefix_None, Pattern_Prefix_Partial, Pattern_Prefix_Exact
} Pattern_Prefix_Status;
/* selfuncs.c */
extern void examine_variable(PlannerInfo *root, Node *node, int varRelid,
VariableStatData *vardata);
extern bool get_restriction_variable(PlannerInfo *root, List *args,
int varRelid,
VariableStatData *vardata, Node **other,
bool *varonleft);
extern void get_join_variables(PlannerInfo *root, List *args,
VariableStatData *vardata1,
VariableStatData *vardata2);
extern double get_variable_numdistinct(VariableStatData *vardata);
extern double mcv_selectivity(VariableStatData *vardata, FmgrInfo *opproc,
Datum constval, bool varonleft,
double *sumcommonp);
extern double histogram_selectivity(VariableStatData *vardata, FmgrInfo *opproc,
Datum constval, bool varonleft,
int min_hist_size, int n_skip);
extern Pattern_Prefix_Status pattern_fixed_prefix(Const *patt,
Pattern_Type ptype,
Const **prefix,
Const **rest);
extern Const *make_greater_string(const Const *str_const, FmgrInfo *ltproc);
extern Datum eqsel(PG_FUNCTION_ARGS);
extern Datum neqsel(PG_FUNCTION_ARGS);
extern Datum scalarltsel(PG_FUNCTION_ARGS);
extern Datum scalargtsel(PG_FUNCTION_ARGS);
extern Datum regexeqsel(PG_FUNCTION_ARGS);
extern Datum icregexeqsel(PG_FUNCTION_ARGS);
extern Datum likesel(PG_FUNCTION_ARGS);
extern Datum iclikesel(PG_FUNCTION_ARGS);
extern Datum regexnesel(PG_FUNCTION_ARGS);
extern Datum icregexnesel(PG_FUNCTION_ARGS);
extern Datum nlikesel(PG_FUNCTION_ARGS);
extern Datum icnlikesel(PG_FUNCTION_ARGS);
extern Datum eqjoinsel(PG_FUNCTION_ARGS);
extern Datum neqjoinsel(PG_FUNCTION_ARGS);
extern Datum scalarltjoinsel(PG_FUNCTION_ARGS);
extern Datum scalargtjoinsel(PG_FUNCTION_ARGS);
extern Datum regexeqjoinsel(PG_FUNCTION_ARGS);
extern Datum icregexeqjoinsel(PG_FUNCTION_ARGS);
extern Datum likejoinsel(PG_FUNCTION_ARGS);
extern Datum iclikejoinsel(PG_FUNCTION_ARGS);
extern Datum regexnejoinsel(PG_FUNCTION_ARGS);
extern Datum icregexnejoinsel(PG_FUNCTION_ARGS);
extern Datum nlikejoinsel(PG_FUNCTION_ARGS);
extern Datum icnlikejoinsel(PG_FUNCTION_ARGS);
extern Selectivity booltestsel(PlannerInfo *root, BoolTestType booltesttype,
Node *arg, int varRelid, JoinType jointype);
extern Selectivity nulltestsel(PlannerInfo *root, NullTestType nulltesttype,
Node *arg, int varRelid, JoinType jointype);
extern Selectivity scalararraysel(PlannerInfo *root,
ScalarArrayOpExpr *clause,
bool is_join_clause,
int varRelid, JoinType jointype);
extern int estimate_array_length(Node *arrayexpr);
extern Selectivity rowcomparesel(PlannerInfo *root,
RowCompareExpr *clause,
int varRelid, JoinType jointype);
extern void mergejoinscansel(PlannerInfo *root, Node *clause,
Oid opfamily, int strategy, bool nulls_first,
Selectivity *leftstart, Selectivity *leftend,
Selectivity *rightstart, Selectivity *rightend);
extern double estimate_num_groups(PlannerInfo *root, List *groupExprs,
double input_rows);
extern Selectivity estimate_hash_bucketsize(PlannerInfo *root, Node *hashkey,
double nbuckets);
extern Datum btcostestimate(PG_FUNCTION_ARGS);
extern Datum hashcostestimate(PG_FUNCTION_ARGS);
extern Datum gistcostestimate(PG_FUNCTION_ARGS);
extern Datum gincostestimate(PG_FUNCTION_ARGS);
#endif /* SELFUNCS_H */