diff options
Diffstat (limited to 'src/backend/utils/adt/like_support.c')
| -rw-r--r-- | src/backend/utils/adt/like_support.c | 13 |
1 files changed, 11 insertions, 2 deletions
diff --git a/src/backend/utils/adt/like_support.c b/src/backend/utils/adt/like_support.c index c746592cbca..241e6f0f598 100644 --- a/src/backend/utils/adt/like_support.c +++ b/src/backend/utils/adt/like_support.c @@ -1442,9 +1442,18 @@ 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); |