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208
pg_include/utils/selfuncs.h
Executable file
208
pg_include/utils/selfuncs.h
Executable file
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/*-------------------------------------------------------------------------
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*
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* selfuncs.h
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* Selectivity functions and index cost estimation functions for
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* standard operators and index access methods.
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*
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*
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* Portions Copyright (c) 1996-2012, 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/utils/selfuncs.h
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*
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*-------------------------------------------------------------------------
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*/
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#ifndef SELFUNCS_H
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#define SELFUNCS_H
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#include "fmgr.h"
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#include "access/htup.h"
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#include "nodes/relation.h"
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/*
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* Note: the default selectivity estimates are not chosen entirely at random.
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* We want them to be small enough to ensure that indexscans will be used if
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* available, for typical table densities of ~100 tuples/page. Thus, for
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* example, 0.01 is not quite small enough, since that makes it appear that
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* nearly all pages will be hit anyway. Also, since we sometimes estimate
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* eqsel as 1/num_distinct, we probably want DEFAULT_NUM_DISTINCT to equal
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* 1/DEFAULT_EQ_SEL.
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*/
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/* default selectivity estimate for equalities such as "A = b" */
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#define DEFAULT_EQ_SEL 0.005
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/* default selectivity estimate for inequalities such as "A < b" */
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#define DEFAULT_INEQ_SEL 0.3333333333333333
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/* default selectivity estimate for range inequalities "A > b AND A < c" */
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#define DEFAULT_RANGE_INEQ_SEL 0.005
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/* default selectivity estimate for pattern-match operators such as LIKE */
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#define DEFAULT_MATCH_SEL 0.005
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/* default number of distinct values in a table */
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#define DEFAULT_NUM_DISTINCT 200
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/* default selectivity estimate for boolean and null test nodes */
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#define DEFAULT_UNK_SEL 0.005
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#define DEFAULT_NOT_UNK_SEL (1.0 - DEFAULT_UNK_SEL)
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/*
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* Clamp a computed probability estimate (which may suffer from roundoff or
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* estimation errors) to valid range. Argument must be a float variable.
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*/
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#define CLAMP_PROBABILITY(p) \
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do { \
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if (p < 0.0) \
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p = 0.0; \
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else if (p > 1.0) \
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p = 1.0; \
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} while (0)
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/* Return data from examine_variable and friends */
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typedef struct VariableStatData
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{
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Node *var; /* the Var or expression tree */
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RelOptInfo *rel; /* Relation, or NULL if not identifiable */
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HeapTuple statsTuple; /* pg_statistic tuple, or NULL if none */
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/* NB: if statsTuple!=NULL, it must be freed when caller is done */
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void (*freefunc) (HeapTuple tuple); /* how to free statsTuple */
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Oid vartype; /* exposed type of expression */
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Oid atttype; /* type to pass to get_attstatsslot */
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int32 atttypmod; /* typmod to pass to get_attstatsslot */
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bool isunique; /* matches unique index or DISTINCT clause */
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} VariableStatData;
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#define ReleaseVariableStats(vardata) \
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do { \
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if (HeapTupleIsValid((vardata).statsTuple)) \
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(* (vardata).freefunc) ((vardata).statsTuple); \
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} while(0)
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typedef enum
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{
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Pattern_Type_Like, Pattern_Type_Like_IC,
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Pattern_Type_Regex, Pattern_Type_Regex_IC
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} Pattern_Type;
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typedef enum
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{
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Pattern_Prefix_None, Pattern_Prefix_Partial, Pattern_Prefix_Exact
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} Pattern_Prefix_Status;
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/* Hooks for plugins to get control when we ask for stats */
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typedef bool (*get_relation_stats_hook_type) (PlannerInfo *root,
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RangeTblEntry *rte,
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AttrNumber attnum,
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VariableStatData *vardata);
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extern PGDLLIMPORT get_relation_stats_hook_type get_relation_stats_hook;
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typedef bool (*get_index_stats_hook_type) (PlannerInfo *root,
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Oid indexOid,
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AttrNumber indexattnum,
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VariableStatData *vardata);
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extern PGDLLIMPORT get_index_stats_hook_type get_index_stats_hook;
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/* Functions in selfuncs.c */
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extern void examine_variable(PlannerInfo *root, Node *node, int varRelid,
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VariableStatData *vardata);
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extern bool get_restriction_variable(PlannerInfo *root, List *args,
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int varRelid,
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VariableStatData *vardata, Node **other,
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bool *varonleft);
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extern void get_join_variables(PlannerInfo *root, List *args,
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SpecialJoinInfo *sjinfo,
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VariableStatData *vardata1,
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VariableStatData *vardata2,
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bool *join_is_reversed);
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extern double get_variable_numdistinct(VariableStatData *vardata,
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bool *isdefault);
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extern double mcv_selectivity(VariableStatData *vardata, FmgrInfo *opproc,
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Datum constval, bool varonleft,
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double *sumcommonp);
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extern double histogram_selectivity(VariableStatData *vardata, FmgrInfo *opproc,
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Datum constval, bool varonleft,
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int min_hist_size, int n_skip,
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int *hist_size);
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extern Pattern_Prefix_Status pattern_fixed_prefix(Const *patt,
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Pattern_Type ptype,
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Oid collation,
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Const **prefix,
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Selectivity *rest_selec);
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extern Const *make_greater_string(const Const *str_const, FmgrInfo *ltproc,
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Oid collation);
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extern Datum eqsel(PG_FUNCTION_ARGS);
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extern Datum neqsel(PG_FUNCTION_ARGS);
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extern Datum scalarltsel(PG_FUNCTION_ARGS);
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extern Datum scalargtsel(PG_FUNCTION_ARGS);
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extern Datum regexeqsel(PG_FUNCTION_ARGS);
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extern Datum icregexeqsel(PG_FUNCTION_ARGS);
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extern Datum likesel(PG_FUNCTION_ARGS);
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extern Datum iclikesel(PG_FUNCTION_ARGS);
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extern Datum regexnesel(PG_FUNCTION_ARGS);
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extern Datum icregexnesel(PG_FUNCTION_ARGS);
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extern Datum nlikesel(PG_FUNCTION_ARGS);
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extern Datum icnlikesel(PG_FUNCTION_ARGS);
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extern Datum eqjoinsel(PG_FUNCTION_ARGS);
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extern Datum neqjoinsel(PG_FUNCTION_ARGS);
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extern Datum scalarltjoinsel(PG_FUNCTION_ARGS);
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extern Datum scalargtjoinsel(PG_FUNCTION_ARGS);
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extern Datum regexeqjoinsel(PG_FUNCTION_ARGS);
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extern Datum icregexeqjoinsel(PG_FUNCTION_ARGS);
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extern Datum likejoinsel(PG_FUNCTION_ARGS);
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extern Datum iclikejoinsel(PG_FUNCTION_ARGS);
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extern Datum regexnejoinsel(PG_FUNCTION_ARGS);
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extern Datum icregexnejoinsel(PG_FUNCTION_ARGS);
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extern Datum nlikejoinsel(PG_FUNCTION_ARGS);
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extern Datum icnlikejoinsel(PG_FUNCTION_ARGS);
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extern Selectivity booltestsel(PlannerInfo *root, BoolTestType booltesttype,
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Node *arg, int varRelid,
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JoinType jointype, SpecialJoinInfo *sjinfo);
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extern Selectivity nulltestsel(PlannerInfo *root, NullTestType nulltesttype,
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Node *arg, int varRelid,
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JoinType jointype, SpecialJoinInfo *sjinfo);
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extern Selectivity scalararraysel(PlannerInfo *root,
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ScalarArrayOpExpr *clause,
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bool is_join_clause,
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int varRelid, JoinType jointype, SpecialJoinInfo *sjinfo);
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extern int estimate_array_length(Node *arrayexpr);
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extern Selectivity rowcomparesel(PlannerInfo *root,
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RowCompareExpr *clause,
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int varRelid, JoinType jointype, SpecialJoinInfo *sjinfo);
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extern void mergejoinscansel(PlannerInfo *root, Node *clause,
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Oid opfamily, int strategy, bool nulls_first,
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Selectivity *leftstart, Selectivity *leftend,
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Selectivity *rightstart, Selectivity *rightend);
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extern double estimate_num_groups(PlannerInfo *root, List *groupExprs,
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double input_rows);
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extern Selectivity estimate_hash_bucketsize(PlannerInfo *root, Node *hashkey,
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double nbuckets);
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extern Datum btcostestimate(PG_FUNCTION_ARGS);
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extern Datum hashcostestimate(PG_FUNCTION_ARGS);
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extern Datum gistcostestimate(PG_FUNCTION_ARGS);
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extern Datum spgcostestimate(PG_FUNCTION_ARGS);
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extern Datum gincostestimate(PG_FUNCTION_ARGS);
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/* Functions in array_selfuncs.c */
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extern Selectivity scalararraysel_containment(PlannerInfo *root,
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Node *leftop, Node *rightop,
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Oid elemtype, bool isEquality, bool useOr,
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int varRelid);
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extern Datum arraycontsel(PG_FUNCTION_ARGS);
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extern Datum arraycontjoinsel(PG_FUNCTION_ARGS);
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#endif /* SELFUNCS_H */
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