diff options
| -rw-r--r-- | contrib/pg_trgm/trgm_gist.c | 20 |
1 files changed, 13 insertions, 7 deletions
diff --git a/contrib/pg_trgm/trgm_gist.c b/contrib/pg_trgm/trgm_gist.c index 178f073755b..c572d0f90f7 100644 --- a/contrib/pg_trgm/trgm_gist.c +++ b/contrib/pg_trgm/trgm_gist.c @@ -401,18 +401,24 @@ gtrgm_consistent(PG_FUNCTION_ARGS) len = ARRNELEM(qtrg); trgm *ptr = GETARR(qtrg); BITVECP sign = GETSIGN(key); + bool *check; - /* descend only if at least one trigram is present */ - res = false; + /* + * GETBIT() tests may give false positives, due to limited + * size of the sign array. But since trigramsMatchGraph() + * implements a monotone boolean function, false positives + * in the check array can't lead to false negative answer. + * So we can apply trigramsMatchGraph despite uncertainty, + * and that usefully improves the quality of the search. + */ + check = (bool *) palloc(len * sizeof(bool)); for (k = 0; k < len; k++) { CPTRGM(((char *) &tmp), ptr + k); - if (GETBIT(sign, HASHVAL(tmp))) - { - res = true; - break; - } + check[k] = GETBIT(sign, HASHVAL(tmp)); } + res = trigramsMatchGraph(cache->graph, check); + pfree(check); } } else |