if (check[i])
ntrue++;
}
-#ifdef DIVUNION
- res = (nkeys == ntrue) ? true : ((((((float4) ntrue) / ((float4) (nkeys - ntrue)))) >= trgm_limit) ? true : false);
-#else
+
+ /*--------------------
+ * If DIVUNION is defined then similarity formula is:
+ * c / (len1 + len2 - c)
+ * where c is number of common trigrams and it stands as ntrue in
+ * this code. Here we don't know value of len2 but we can assume
+ * that c (ntrue) is a lower bound of len2, so upper bound of
+ * similarity is:
+ * c / (len1 + c - c) => c / len1
+ * If DIVUNION is not defined then similarity formula is:
+ * c / max(len1, len2)
+ * And again, c (ntrue) is a lower bound of len2, but c <= len1
+ * just by definition and, consequently, upper bound of
+ * similarity is just c / len1.
+ * So, independly on DIVUNION the upper bound formula is the same.
+ */
res = (nkeys == 0) ? false : ((((((float4) ntrue) / ((float4) nkeys))) >= trgm_limit) ? true : false);
-#endif
break;
case ILikeStrategyNumber:
#ifndef IGNORECASE
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
+
+ /*
+ * See comment in gin_trgm_consistent() about * upper bound formula
+ */
res = (nkeys == 0) ? GIN_FALSE : (((((float4) ntrue) / ((float4) nkeys)) >= trgm_limit) ? GIN_MAYBE : GIN_FALSE);
-#endif
break;
case ILikeStrategyNumber:
#ifndef IGNORECASE