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Diffstat (limited to 'src/include/utils/selfuncs.h')
| -rw-r--r-- | src/include/utils/selfuncs.h | 223 |
1 files changed, 223 insertions, 0 deletions
diff --git a/src/include/utils/selfuncs.h b/src/include/utils/selfuncs.h new file mode 100644 index 0000000..7ac4a06 --- /dev/null +++ b/src/include/utils/selfuncs.h @@ -0,0 +1,223 @@ +/*------------------------------------------------------------------------- + * + * selfuncs.h + * Selectivity functions for standard operators, and assorted + * infrastructure for selectivity and cost estimation. + * + * + * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group + * Portions Copyright (c) 1994, Regents of the University of California + * + * src/include/utils/selfuncs.h + * + *------------------------------------------------------------------------- + */ +#ifndef SELFUNCS_H +#define SELFUNCS_H + +#include "access/htup.h" +#include "fmgr.h" +#include "nodes/pathnodes.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 selectivity estimate for other matching operators */ +#define DEFAULT_MATCHING_SEL 0.010 + +/* 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 VariableStatData +{ + 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 */ + void (*freefunc) (HeapTuple tuple); /* how to free statsTuple */ + Oid vartype; /* exposed type of expression */ + Oid atttype; /* actual type (after stripping relabel) */ + int32 atttypmod; /* actual typmod (after stripping relabel) */ + bool isunique; /* matches unique index or DISTINCT clause */ + bool acl_ok; /* result of ACL check on table or column */ +} VariableStatData; + +#define ReleaseVariableStats(vardata) \ + do { \ + if (HeapTupleIsValid((vardata).statsTuple)) \ + (vardata).freefunc((vardata).statsTuple); \ + } while(0) + + +/* + * genericcostestimate is a general-purpose estimator that can be used for + * most index types. In some cases we use genericcostestimate as the base + * code and then incorporate additional index-type-specific knowledge in + * the type-specific calling function. To avoid code duplication, we make + * genericcostestimate return a number of intermediate values as well as + * its preliminary estimates of the output cost values. The GenericCosts + * struct includes all these values. + * + * Callers should initialize all fields of GenericCosts to zero. In addition, + * they can set numIndexTuples to some positive value if they have a better + * than default way of estimating the number of leaf index tuples visited. + */ +typedef struct +{ + /* These are the values the cost estimator must return to the planner */ + Cost indexStartupCost; /* index-related startup cost */ + Cost indexTotalCost; /* total index-related scan cost */ + Selectivity indexSelectivity; /* selectivity of index */ + double indexCorrelation; /* order correlation of index */ + + /* Intermediate values we obtain along the way */ + double numIndexPages; /* number of leaf pages visited */ + double numIndexTuples; /* number of leaf tuples visited */ + double spc_random_page_cost; /* relevant random_page_cost value */ + double num_sa_scans; /* # indexscans from ScalarArrayOpExprs */ +} GenericCosts; + +/* Hooks for plugins to get control when we ask for stats */ +typedef bool (*get_relation_stats_hook_type) (PlannerInfo *root, + RangeTblEntry *rte, + AttrNumber attnum, + VariableStatData *vardata); +extern PGDLLIMPORT get_relation_stats_hook_type get_relation_stats_hook; +typedef bool (*get_index_stats_hook_type) (PlannerInfo *root, + Oid indexOid, + AttrNumber indexattnum, + VariableStatData *vardata); +extern PGDLLIMPORT get_index_stats_hook_type get_index_stats_hook; + +/* Functions in selfuncs.c */ + +extern void examine_variable(PlannerInfo *root, Node *node, int varRelid, + VariableStatData *vardata); +extern bool statistic_proc_security_check(VariableStatData *vardata, Oid func_oid); +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, + SpecialJoinInfo *sjinfo, + VariableStatData *vardata1, + VariableStatData *vardata2, + bool *join_is_reversed); +extern double get_variable_numdistinct(VariableStatData *vardata, + bool *isdefault); +extern double mcv_selectivity(VariableStatData *vardata, + FmgrInfo *opproc, Oid collation, + Datum constval, bool varonleft, + double *sumcommonp); +extern double histogram_selectivity(VariableStatData *vardata, + FmgrInfo *opproc, Oid collation, + Datum constval, bool varonleft, + int min_hist_size, int n_skip, + int *hist_size); +extern double generic_restriction_selectivity(PlannerInfo *root, + Oid oproid, Oid collation, + List *args, int varRelid, + double default_selectivity); +extern double ineq_histogram_selectivity(PlannerInfo *root, + VariableStatData *vardata, + Oid opoid, FmgrInfo *opproc, + bool isgt, bool iseq, + Oid collation, + Datum constval, Oid consttype); +extern double var_eq_const(VariableStatData *vardata, + Oid oproid, Oid collation, + Datum constval, bool constisnull, + bool varonleft, bool negate); +extern double var_eq_non_const(VariableStatData *vardata, + Oid oproid, Oid collation, + Node *other, + bool varonleft, bool negate); + +extern Selectivity boolvarsel(PlannerInfo *root, Node *arg, int varRelid); +extern Selectivity booltestsel(PlannerInfo *root, BoolTestType booltesttype, + Node *arg, int varRelid, + JoinType jointype, SpecialJoinInfo *sjinfo); +extern Selectivity nulltestsel(PlannerInfo *root, NullTestType nulltesttype, + Node *arg, int varRelid, + JoinType jointype, SpecialJoinInfo *sjinfo); +extern Selectivity scalararraysel(PlannerInfo *root, + ScalarArrayOpExpr *clause, + bool is_join_clause, + int varRelid, JoinType jointype, SpecialJoinInfo *sjinfo); +extern int estimate_array_length(Node *arrayexpr); +extern Selectivity rowcomparesel(PlannerInfo *root, + RowCompareExpr *clause, + int varRelid, JoinType jointype, SpecialJoinInfo *sjinfo); + +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, List **pgset); + +extern void estimate_hash_bucket_stats(PlannerInfo *root, + Node *hashkey, double nbuckets, + Selectivity *mcv_freq, + Selectivity *bucketsize_frac); +extern double estimate_hashagg_tablesize(Path *path, + const AggClauseCosts *agg_costs, + double dNumGroups); + +extern List *get_quals_from_indexclauses(List *indexclauses); +extern Cost index_other_operands_eval_cost(PlannerInfo *root, + List *indexquals); +extern List *add_predicate_to_index_quals(IndexOptInfo *index, + List *indexQuals); +extern void genericcostestimate(PlannerInfo *root, IndexPath *path, + double loop_count, + GenericCosts *costs); + +/* Functions in array_selfuncs.c */ + +extern Selectivity scalararraysel_containment(PlannerInfo *root, + Node *leftop, Node *rightop, + Oid elemtype, bool isEquality, bool useOr, + int varRelid); + +#endif /* SELFUNCS_H */ |