diff options
Diffstat (limited to 'contrib/intarray/_int_selfuncs.c')
| -rw-r--r-- | contrib/intarray/_int_selfuncs.c | 333 |
1 files changed, 333 insertions, 0 deletions
diff --git a/contrib/intarray/_int_selfuncs.c b/contrib/intarray/_int_selfuncs.c new file mode 100644 index 0000000..a3a538a --- /dev/null +++ b/contrib/intarray/_int_selfuncs.c @@ -0,0 +1,333 @@ +/*------------------------------------------------------------------------- + * + * _int_selfuncs.c + * Functions for selectivity estimation of intarray operators + * + * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group + * Portions Copyright (c) 1994, Regents of the University of California + * + * + * IDENTIFICATION + * contrib/intarray/_int_selfuncs.c + * + *------------------------------------------------------------------------- + */ +#include "postgres.h" + +#include "_int.h" +#include "access/htup_details.h" +#include "catalog/pg_operator.h" +#include "catalog/pg_statistic.h" +#include "catalog/pg_type.h" +#include "miscadmin.h" +#include "utils/builtins.h" +#include "utils/lsyscache.h" +#include "utils/selfuncs.h" +#include "utils/syscache.h" + +PG_FUNCTION_INFO_V1(_int_overlap_sel); +PG_FUNCTION_INFO_V1(_int_contains_sel); +PG_FUNCTION_INFO_V1(_int_contained_sel); +PG_FUNCTION_INFO_V1(_int_overlap_joinsel); +PG_FUNCTION_INFO_V1(_int_contains_joinsel); +PG_FUNCTION_INFO_V1(_int_contained_joinsel); +PG_FUNCTION_INFO_V1(_int_matchsel); + + +static Selectivity int_query_opr_selec(ITEM *item, Datum *values, float4 *freqs, + int nmncelems, float4 minfreq); +static int compare_val_int4(const void *a, const void *b); + +/* + * Wrappers around the default array selectivity estimation functions. + * + * The default array selectivity operators for the @>, && and @< operators + * work fine for integer arrays. However, if we tried to just use arraycontsel + * and arraycontjoinsel directly as the cost estimator functions for our + * operators, they would not work as intended, because they look at the + * operator's OID. Our operators behave exactly like the built-in anyarray + * versions, but we must tell the cost estimator functions which built-in + * operators they correspond to. These wrappers just replace the operator + * OID with the corresponding built-in operator's OID, and call the built-in + * function. + */ + +Datum +_int_overlap_sel(PG_FUNCTION_ARGS) +{ + PG_RETURN_DATUM(DirectFunctionCall4(arraycontsel, + PG_GETARG_DATUM(0), + ObjectIdGetDatum(OID_ARRAY_OVERLAP_OP), + PG_GETARG_DATUM(2), + PG_GETARG_DATUM(3))); +} + +Datum +_int_contains_sel(PG_FUNCTION_ARGS) +{ + PG_RETURN_DATUM(DirectFunctionCall4(arraycontsel, + PG_GETARG_DATUM(0), + ObjectIdGetDatum(OID_ARRAY_CONTAINS_OP), + PG_GETARG_DATUM(2), + PG_GETARG_DATUM(3))); +} + +Datum +_int_contained_sel(PG_FUNCTION_ARGS) +{ + PG_RETURN_DATUM(DirectFunctionCall4(arraycontsel, + PG_GETARG_DATUM(0), + ObjectIdGetDatum(OID_ARRAY_CONTAINED_OP), + PG_GETARG_DATUM(2), + PG_GETARG_DATUM(3))); +} + +Datum +_int_overlap_joinsel(PG_FUNCTION_ARGS) +{ + PG_RETURN_DATUM(DirectFunctionCall5(arraycontjoinsel, + PG_GETARG_DATUM(0), + ObjectIdGetDatum(OID_ARRAY_OVERLAP_OP), + PG_GETARG_DATUM(2), + PG_GETARG_DATUM(3), + PG_GETARG_DATUM(4))); +} + +Datum +_int_contains_joinsel(PG_FUNCTION_ARGS) +{ + PG_RETURN_DATUM(DirectFunctionCall5(arraycontjoinsel, + PG_GETARG_DATUM(0), + ObjectIdGetDatum(OID_ARRAY_CONTAINS_OP), + PG_GETARG_DATUM(2), + PG_GETARG_DATUM(3), + PG_GETARG_DATUM(4))); +} + +Datum +_int_contained_joinsel(PG_FUNCTION_ARGS) +{ + PG_RETURN_DATUM(DirectFunctionCall5(arraycontjoinsel, + PG_GETARG_DATUM(0), + ObjectIdGetDatum(OID_ARRAY_CONTAINED_OP), + PG_GETARG_DATUM(2), + PG_GETARG_DATUM(3), + PG_GETARG_DATUM(4))); +} + + +/* + * _int_matchsel -- restriction selectivity function for intarray @@ query_int + */ +Datum +_int_matchsel(PG_FUNCTION_ARGS) +{ + PlannerInfo *root = (PlannerInfo *) PG_GETARG_POINTER(0); + + List *args = (List *) PG_GETARG_POINTER(2); + int varRelid = PG_GETARG_INT32(3); + VariableStatData vardata; + Node *other; + bool varonleft; + Selectivity selec; + QUERYTYPE *query; + Datum *mcelems = NULL; + float4 *mcefreqs = NULL; + int nmcelems = 0; + float4 minfreq = 0.0; + float4 nullfrac = 0.0; + AttStatsSlot sslot; + + /* + * If expression is not "variable @@ something" or "something @@ variable" + * then punt and return a default estimate. + */ + if (!get_restriction_variable(root, args, varRelid, + &vardata, &other, &varonleft)) + PG_RETURN_FLOAT8(DEFAULT_EQ_SEL); + + /* + * Variable should be int[]. We don't support cases where variable is + * query_int. + */ + if (vardata.vartype != INT4ARRAYOID) + PG_RETURN_FLOAT8(DEFAULT_EQ_SEL); + + /* + * Can't do anything useful if the something is not a constant, either. + */ + if (!IsA(other, Const)) + { + ReleaseVariableStats(vardata); + PG_RETURN_FLOAT8(DEFAULT_EQ_SEL); + } + + /* + * The "@@" operator is strict, so we can cope with NULL right away. + */ + if (((Const *) other)->constisnull) + { + ReleaseVariableStats(vardata); + PG_RETURN_FLOAT8(0.0); + } + + /* The caller made sure the const is a query, so get it now */ + query = DatumGetQueryTypeP(((Const *) other)->constvalue); + + /* Empty query matches nothing */ + if (query->size == 0) + { + ReleaseVariableStats(vardata); + return (Selectivity) 0.0; + } + + /* + * Get the statistics for the intarray column. + * + * We're interested in the Most-Common-Elements list, and the NULL + * fraction. + */ + if (HeapTupleIsValid(vardata.statsTuple)) + { + Form_pg_statistic stats; + + stats = (Form_pg_statistic) GETSTRUCT(vardata.statsTuple); + nullfrac = stats->stanullfrac; + + /* + * For an int4 array, the default array type analyze function will + * collect a Most Common Elements list, which is an array of int4s. + */ + if (get_attstatsslot(&sslot, vardata.statsTuple, + STATISTIC_KIND_MCELEM, InvalidOid, + ATTSTATSSLOT_VALUES | ATTSTATSSLOT_NUMBERS)) + { + Assert(sslot.valuetype == INT4OID); + + /* + * There should be three more Numbers than Values, because the + * last three (for intarray) cells are taken for minimal, maximal + * and nulls frequency. Punt if not. + */ + if (sslot.nnumbers == sslot.nvalues + 3) + { + /* Grab the lowest frequency. */ + minfreq = sslot.numbers[sslot.nnumbers - (sslot.nnumbers - sslot.nvalues)]; + + mcelems = sslot.values; + mcefreqs = sslot.numbers; + nmcelems = sslot.nvalues; + } + } + } + else + memset(&sslot, 0, sizeof(sslot)); + + /* Process the logical expression in the query, using the stats */ + selec = int_query_opr_selec(GETQUERY(query) + query->size - 1, + mcelems, mcefreqs, nmcelems, minfreq); + + /* MCE stats count only non-null rows, so adjust for null rows. */ + selec *= (1.0 - nullfrac); + + free_attstatsslot(&sslot); + ReleaseVariableStats(vardata); + + CLAMP_PROBABILITY(selec); + + PG_RETURN_FLOAT8((float8) selec); +} + +/* + * Estimate selectivity of single intquery operator + */ +static Selectivity +int_query_opr_selec(ITEM *item, Datum *mcelems, float4 *mcefreqs, + int nmcelems, float4 minfreq) +{ + Selectivity selec; + + /* since this function recurses, it could be driven to stack overflow */ + check_stack_depth(); + + if (item->type == VAL) + { + Datum *searchres; + + if (mcelems == NULL) + return (Selectivity) DEFAULT_EQ_SEL; + + searchres = (Datum *) bsearch(&item->val, mcelems, nmcelems, + sizeof(Datum), compare_val_int4); + if (searchres) + { + /* + * The element is in MCELEM. Return precise selectivity (or at + * least as precise as ANALYZE could find out). + */ + selec = mcefreqs[searchres - mcelems]; + } + else + { + /* + * The element is not in MCELEM. Punt, but assume that the + * selectivity cannot be more than minfreq / 2. + */ + selec = Min(DEFAULT_EQ_SEL, minfreq / 2); + } + } + else if (item->type == OPR) + { + /* Current query node is an operator */ + Selectivity s1, + s2; + + s1 = int_query_opr_selec(item - 1, mcelems, mcefreqs, nmcelems, + minfreq); + switch (item->val) + { + case (int32) '!': + selec = 1.0 - s1; + break; + + case (int32) '&': + s2 = int_query_opr_selec(item + item->left, mcelems, mcefreqs, + nmcelems, minfreq); + selec = s1 * s2; + break; + + case (int32) '|': + s2 = int_query_opr_selec(item + item->left, mcelems, mcefreqs, + nmcelems, minfreq); + selec = s1 + s2 - s1 * s2; + break; + + default: + elog(ERROR, "unrecognized operator: %d", item->val); + selec = 0; /* keep compiler quiet */ + break; + } + } + else + { + elog(ERROR, "unrecognized int query item type: %u", item->type); + selec = 0; /* keep compiler quiet */ + } + + /* Clamp intermediate results to stay sane despite roundoff error */ + CLAMP_PROBABILITY(selec); + + return selec; +} + +/* + * Comparison function for binary search in mcelem array. + */ +static int +compare_val_int4(const void *a, const void *b) +{ + int32 key = *(int32 *) a; + const Datum *t = (const Datum *) b; + + return key - DatumGetInt32(*t); +} |