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This supports the triconsistent function for pg_trgm GIN opclass

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to make it faster to implement indexed queries where some keys are
common and some are rare.

Patch by Jeff Janes
This commit is contained in:
Teodor Sigaev
2015-07-20 18:18:48 +03:00
parent 1a51180080
commit 97f3014647
5 changed files with 117 additions and 3 deletions
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92
contrib/pg_trgm/trgm_gin.c
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@ -14,6 +14,7 @@ PG_FUNCTION_INFO_V1(gin_extract_trgm);
PG_FUNCTION_INFO_V1(gin_extract_value_trgm);
PG_FUNCTION_INFO_V1(gin_extract_query_trgm);
PG_FUNCTION_INFO_V1(gin_trgm_consistent);
PG_FUNCTION_INFO_V1(gin_trgm_triconsistent);
/*
* This function can only be called if a pre-9.1 version of the GIN operator
@ -235,3 +236,94 @@ gin_trgm_consistent(PG_FUNCTION_ARGS)
PG_RETURN_BOOL(res);
}
/*
* In all cases, GIN_TRUE is at least as favorable to inclusion as
* GIN_MAYBE. If no better option is available, simply treat
* GIN_MAYBE as if it were GIN_TRUE and apply the same test as the binary
* consistent function.
*/
Datum
gin_trgm_triconsistent(PG_FUNCTION_ARGS)
{
GinTernaryValue *check = (GinTernaryValue *) PG_GETARG_POINTER(0);
StrategyNumber strategy = PG_GETARG_UINT16(1);
/* text *query = PG_GETARG_TEXT_P(2); */
int32 nkeys = PG_GETARG_INT32(3);
Pointer *extra_data = (Pointer *) PG_GETARG_POINTER(4);
GinTernaryValue res = GIN_MAYBE;
int32 i,
ntrue;
bool *boolcheck;
switch (strategy)
{
case SimilarityStrategyNumber:
/* Count the matches */
ntrue = 0;
for (i = 0; i < nkeys; i++)
{
if (check[i] != GIN_FALSE)
ntrue++;
}
#ifdef DIVUNION
res = (nkeys == ntrue) ? GIN_MAYBE : (((((float4) ntrue) / ((float4) (nkeys - ntrue))) >= trgm_limit) ? GIN_MAYBE : GIN_FALSE);
#else
res = (nkeys == 0) ? GIN_FALSE : (((((float4) ntrue) / ((float4) nkeys)) >= trgm_limit) ? GIN_MAYBE : GIN_FALSE);
#endif
break;
case ILikeStrategyNumber:
#ifndef IGNORECASE
elog(ERROR, "cannot handle ~~* with case-sensitive trigrams");
#endif
/* FALL THRU */
case LikeStrategyNumber:
/* Check if all extracted trigrams are presented. */
res = GIN_MAYBE;
for (i = 0; i < nkeys; i++)
{
if (check[i] == GIN_FALSE)
{
res = GIN_FALSE;
break;
}
}
break;
case RegExpICaseStrategyNumber:
#ifndef IGNORECASE
elog(ERROR, "cannot handle ~* with case-sensitive trigrams");
#endif
/* FALL THRU */
case RegExpStrategyNumber:
if (nkeys < 1)
{
/* Regex processing gave no result: do full index scan */
res = GIN_MAYBE;
}
else
{
/*
* As trigramsMatchGraph implements a montonic boolean function,
* promoting all GIN_MAYBE keys to GIN_TRUE will give a
* conservative result.
*/
boolcheck = (bool *) palloc(sizeof(bool) * nkeys);
for (i = 0; i < nkeys; i++)
boolcheck[i] = (check[i] != GIN_FALSE);
if (!trigramsMatchGraph((TrgmPackedGraph *) extra_data[0],
boolcheck))
res = GIN_FALSE;
pfree(boolcheck);
}
break;
default:
elog(ERROR, "unrecognized strategy number: %d", strategy);
res = GIN_FALSE; /* keep compiler quiet */
break;
}
/* All cases served by this function are inexact */
Assert(res != GIN_TRUE);
PG_RETURN_GIN_TERNARY_VALUE(res);
}