mirror of
https://github.com/postgres/postgres.git
synced 2026-02-20 08:20:55 -05:00
3a02d68a96
Given a regex pattern with a very long fixed prefix (approaching 500 characters), the result of pow(FIXED_CHAR_SEL, fixed_prefix_len) can underflow to zero. Typically the preceding selectivity calculation would have underflowed as well, so that we compute 0/0 and get NaN. In released branches this leads to an assertion failure later on. That doesn't happen in HEAD, for reasons I've not explored yet, but it's surely still a bug. To fix, just skip the division when the pow() result is zero, so that we'll (most likely) return a zero selectivity estimate. In the edge cases where "sel" didn't yet underflow, perhaps this isn't desirable, but I'm not sure that the case is worth spending a lot of effort on. The results of regex_selectivity_sub() are barely worth the electrons they're written on anyway :-( Per report from Alexander Lakhin. Back-patch to all supported versions. Discussion: https://postgr.es/m/6de0a0c3-ada9-cd0c-3e4e-2fa9964b41e3@gmail.com |
||
|---|---|---|
| .. | ||
| backend | ||
| bin | ||
| common | ||
| fe_utils | ||
| include | ||
| interfaces | ||
| makefiles | ||
| pl | ||
| port | ||
| template | ||
| test | ||
| timezone | ||
| tools | ||
| tutorial | ||
| .gitignore | ||
| DEVELOPERS | ||
| Makefile | ||
| Makefile.global.in | ||
| Makefile.shlib | ||
| nls-global.mk | ||