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Viewing changes to src/include/utils/selfuncs.h

  • Committer: Bazaar Package Importer
  • Author(s): Martin Pitt
  • Date: 2009-03-20 12:00:13 UTC
  • Revision ID: james.westby@ubuntu.com-20090320120013-hogj7egc5mjncc5g
Tags: upstream-8.4~0cvs20090328
Import upstream version 8.4~0cvs20090328

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src/include/utils/selfuncs.h
 
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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) 1996-2009, 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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 * $PostgreSQL$
 
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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;               /* true if matched to a unique index */
 
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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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/* selfuncs.c */
 
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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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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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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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                                         Const **prefix,
 
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                                         Const **rest);
 
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extern Const *make_greater_string(const Const *str_const, FmgrInfo *ltproc);
 
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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);
 
179
 
 
180
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);
 
190
 
 
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extern Datum btcostestimate(PG_FUNCTION_ARGS);
 
192
extern Datum hashcostestimate(PG_FUNCTION_ARGS);
 
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extern Datum gistcostestimate(PG_FUNCTION_ARGS);
 
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extern Datum gincostestimate(PG_FUNCTION_ARGS);
 
195
 
 
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#endif   /* SELFUNCS_H */