diff options
| -rw-r--r-- | src/backend/utils/adt/selfuncs.c | 13 |
1 files changed, 11 insertions, 2 deletions
diff --git a/src/backend/utils/adt/selfuncs.c b/src/backend/utils/adt/selfuncs.c index b7313687169..e128dccb04b 100644 --- a/src/backend/utils/adt/selfuncs.c +++ b/src/backend/utils/adt/selfuncs.c @@ -6087,9 +6087,18 @@ regex_selectivity(const char *patt, int pattlen, bool case_insensitive, sel *= FULL_WILDCARD_SEL; } - /* If there's a fixed prefix, discount its selectivity */ + /* + * If there's a fixed prefix, discount its selectivity. We have to be + * careful here since a very long prefix could result in pow's result + * underflowing to zero (in which case "sel" probably has as well). + */ if (fixed_prefix_len > 0) - sel /= pow(FIXED_CHAR_SEL, fixed_prefix_len); + { + double prefixsel = pow(FIXED_CHAR_SEL, fixed_prefix_len); + + if (prefixsel > 0.0) + sel /= prefixsel; + } /* Make sure result stays in range */ CLAMP_PROBABILITY(sel); |