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00001 /*------------------------------------------------------------------------- 00002 * 00003 * selfuncs.h 00004 * Selectivity functions and index cost estimation functions for 00005 * standard operators and index access methods. 00006 * 00007 * 00008 * Portions Copyright (c) 1996-2013, PostgreSQL Global Development Group 00009 * Portions Copyright (c) 1994, Regents of the University of California 00010 * 00011 * src/include/utils/selfuncs.h 00012 * 00013 *------------------------------------------------------------------------- 00014 */ 00015 #ifndef SELFUNCS_H 00016 #define SELFUNCS_H 00017 00018 #include "fmgr.h" 00019 #include "access/htup.h" 00020 #include "nodes/relation.h" 00021 00022 00023 /* 00024 * Note: the default selectivity estimates are not chosen entirely at random. 00025 * We want them to be small enough to ensure that indexscans will be used if 00026 * available, for typical table densities of ~100 tuples/page. Thus, for 00027 * example, 0.01 is not quite small enough, since that makes it appear that 00028 * nearly all pages will be hit anyway. Also, since we sometimes estimate 00029 * eqsel as 1/num_distinct, we probably want DEFAULT_NUM_DISTINCT to equal 00030 * 1/DEFAULT_EQ_SEL. 00031 */ 00032 00033 /* default selectivity estimate for equalities such as "A = b" */ 00034 #define DEFAULT_EQ_SEL 0.005 00035 00036 /* default selectivity estimate for inequalities such as "A < b" */ 00037 #define DEFAULT_INEQ_SEL 0.3333333333333333 00038 00039 /* default selectivity estimate for range inequalities "A > b AND A < c" */ 00040 #define DEFAULT_RANGE_INEQ_SEL 0.005 00041 00042 /* default selectivity estimate for pattern-match operators such as LIKE */ 00043 #define DEFAULT_MATCH_SEL 0.005 00044 00045 /* default number of distinct values in a table */ 00046 #define DEFAULT_NUM_DISTINCT 200 00047 00048 /* default selectivity estimate for boolean and null test nodes */ 00049 #define DEFAULT_UNK_SEL 0.005 00050 #define DEFAULT_NOT_UNK_SEL (1.0 - DEFAULT_UNK_SEL) 00051 00052 00053 /* 00054 * Clamp a computed probability estimate (which may suffer from roundoff or 00055 * estimation errors) to valid range. Argument must be a float variable. 00056 */ 00057 #define CLAMP_PROBABILITY(p) \ 00058 do { \ 00059 if (p < 0.0) \ 00060 p = 0.0; \ 00061 else if (p > 1.0) \ 00062 p = 1.0; \ 00063 } while (0) 00064 00065 00066 /* Return data from examine_variable and friends */ 00067 typedef struct VariableStatData 00068 { 00069 Node *var; /* the Var or expression tree */ 00070 RelOptInfo *rel; /* Relation, or NULL if not identifiable */ 00071 HeapTuple statsTuple; /* pg_statistic tuple, or NULL if none */ 00072 /* NB: if statsTuple!=NULL, it must be freed when caller is done */ 00073 void (*freefunc) (HeapTuple tuple); /* how to free statsTuple */ 00074 Oid vartype; /* exposed type of expression */ 00075 Oid atttype; /* type to pass to get_attstatsslot */ 00076 int32 atttypmod; /* typmod to pass to get_attstatsslot */ 00077 bool isunique; /* matches unique index or DISTINCT clause */ 00078 } VariableStatData; 00079 00080 #define ReleaseVariableStats(vardata) \ 00081 do { \ 00082 if (HeapTupleIsValid((vardata).statsTuple)) \ 00083 (* (vardata).freefunc) ((vardata).statsTuple); \ 00084 } while(0) 00085 00086 00087 typedef enum 00088 { 00089 Pattern_Type_Like, Pattern_Type_Like_IC, 00090 Pattern_Type_Regex, Pattern_Type_Regex_IC 00091 } Pattern_Type; 00092 00093 typedef enum 00094 { 00095 Pattern_Prefix_None, Pattern_Prefix_Partial, Pattern_Prefix_Exact 00096 } Pattern_Prefix_Status; 00097 00098 /* Hooks for plugins to get control when we ask for stats */ 00099 typedef bool (*get_relation_stats_hook_type) (PlannerInfo *root, 00100 RangeTblEntry *rte, 00101 AttrNumber attnum, 00102 VariableStatData *vardata); 00103 extern PGDLLIMPORT get_relation_stats_hook_type get_relation_stats_hook; 00104 typedef bool (*get_index_stats_hook_type) (PlannerInfo *root, 00105 Oid indexOid, 00106 AttrNumber indexattnum, 00107 VariableStatData *vardata); 00108 extern PGDLLIMPORT get_index_stats_hook_type get_index_stats_hook; 00109 00110 /* Functions in selfuncs.c */ 00111 00112 extern void examine_variable(PlannerInfo *root, Node *node, int varRelid, 00113 VariableStatData *vardata); 00114 extern bool get_restriction_variable(PlannerInfo *root, List *args, 00115 int varRelid, 00116 VariableStatData *vardata, Node **other, 00117 bool *varonleft); 00118 extern void get_join_variables(PlannerInfo *root, List *args, 00119 SpecialJoinInfo *sjinfo, 00120 VariableStatData *vardata1, 00121 VariableStatData *vardata2, 00122 bool *join_is_reversed); 00123 extern double get_variable_numdistinct(VariableStatData *vardata, 00124 bool *isdefault); 00125 extern double mcv_selectivity(VariableStatData *vardata, FmgrInfo *opproc, 00126 Datum constval, bool varonleft, 00127 double *sumcommonp); 00128 extern double histogram_selectivity(VariableStatData *vardata, FmgrInfo *opproc, 00129 Datum constval, bool varonleft, 00130 int min_hist_size, int n_skip, 00131 int *hist_size); 00132 00133 extern Pattern_Prefix_Status pattern_fixed_prefix(Const *patt, 00134 Pattern_Type ptype, 00135 Oid collation, 00136 Const **prefix, 00137 Selectivity *rest_selec); 00138 extern Const *make_greater_string(const Const *str_const, FmgrInfo *ltproc, 00139 Oid collation); 00140 00141 extern Datum eqsel(PG_FUNCTION_ARGS); 00142 extern Datum neqsel(PG_FUNCTION_ARGS); 00143 extern Datum scalarltsel(PG_FUNCTION_ARGS); 00144 extern Datum scalargtsel(PG_FUNCTION_ARGS); 00145 extern Datum regexeqsel(PG_FUNCTION_ARGS); 00146 extern Datum icregexeqsel(PG_FUNCTION_ARGS); 00147 extern Datum likesel(PG_FUNCTION_ARGS); 00148 extern Datum iclikesel(PG_FUNCTION_ARGS); 00149 extern Datum regexnesel(PG_FUNCTION_ARGS); 00150 extern Datum icregexnesel(PG_FUNCTION_ARGS); 00151 extern Datum nlikesel(PG_FUNCTION_ARGS); 00152 extern Datum icnlikesel(PG_FUNCTION_ARGS); 00153 00154 extern Datum eqjoinsel(PG_FUNCTION_ARGS); 00155 extern Datum neqjoinsel(PG_FUNCTION_ARGS); 00156 extern Datum scalarltjoinsel(PG_FUNCTION_ARGS); 00157 extern Datum scalargtjoinsel(PG_FUNCTION_ARGS); 00158 extern Datum regexeqjoinsel(PG_FUNCTION_ARGS); 00159 extern Datum icregexeqjoinsel(PG_FUNCTION_ARGS); 00160 extern Datum likejoinsel(PG_FUNCTION_ARGS); 00161 extern Datum iclikejoinsel(PG_FUNCTION_ARGS); 00162 extern Datum regexnejoinsel(PG_FUNCTION_ARGS); 00163 extern Datum icregexnejoinsel(PG_FUNCTION_ARGS); 00164 extern Datum nlikejoinsel(PG_FUNCTION_ARGS); 00165 extern Datum icnlikejoinsel(PG_FUNCTION_ARGS); 00166 00167 extern Selectivity booltestsel(PlannerInfo *root, BoolTestType booltesttype, 00168 Node *arg, int varRelid, 00169 JoinType jointype, SpecialJoinInfo *sjinfo); 00170 extern Selectivity nulltestsel(PlannerInfo *root, NullTestType nulltesttype, 00171 Node *arg, int varRelid, 00172 JoinType jointype, SpecialJoinInfo *sjinfo); 00173 extern Selectivity scalararraysel(PlannerInfo *root, 00174 ScalarArrayOpExpr *clause, 00175 bool is_join_clause, 00176 int varRelid, JoinType jointype, SpecialJoinInfo *sjinfo); 00177 extern int estimate_array_length(Node *arrayexpr); 00178 extern Selectivity rowcomparesel(PlannerInfo *root, 00179 RowCompareExpr *clause, 00180 int varRelid, JoinType jointype, SpecialJoinInfo *sjinfo); 00181 00182 extern void mergejoinscansel(PlannerInfo *root, Node *clause, 00183 Oid opfamily, int strategy, bool nulls_first, 00184 Selectivity *leftstart, Selectivity *leftend, 00185 Selectivity *rightstart, Selectivity *rightend); 00186 00187 extern double estimate_num_groups(PlannerInfo *root, List *groupExprs, 00188 double input_rows); 00189 00190 extern Selectivity estimate_hash_bucketsize(PlannerInfo *root, Node *hashkey, 00191 double nbuckets); 00192 00193 extern Datum btcostestimate(PG_FUNCTION_ARGS); 00194 extern Datum hashcostestimate(PG_FUNCTION_ARGS); 00195 extern Datum gistcostestimate(PG_FUNCTION_ARGS); 00196 extern Datum spgcostestimate(PG_FUNCTION_ARGS); 00197 extern Datum gincostestimate(PG_FUNCTION_ARGS); 00198 00199 /* Functions in array_selfuncs.c */ 00200 00201 extern Selectivity scalararraysel_containment(PlannerInfo *root, 00202 Node *leftop, Node *rightop, 00203 Oid elemtype, bool isEquality, bool useOr, 00204 int varRelid); 00205 extern Datum arraycontsel(PG_FUNCTION_ARGS); 00206 extern Datum arraycontjoinsel(PG_FUNCTION_ARGS); 00207 00208 #endif /* SELFUNCS_H */
1.7.1