Re: Strange choice of general index over partial index
| От | Mark Kirkwood |
|---|---|
| Тема | Re: Strange choice of general index over partial index |
| Дата | |
| Msg-id | 54B88CEC.9080009@catalyst.net.nz обсуждение исходный текст |
| Ответ на | Re: Strange choice of general index over partial index (Josh Berkus <josh@agliodbs.com>) |
| Список | pgsql-performance |
On 16/01/15 16:28, Josh Berkus wrote: > On 01/16/2015 04:17 PM, Mark Kirkwood wrote: >> On 16/01/15 16:06, Mark Kirkwood wrote: >> >>> A bit more poking about shows that the major factor (which this fake >>> dataset anyway) is the default for effective_cache_size (changes from >>> 128MB to 4GB in 9.4). Increasing this makes 9.2 start using the >>> files_in_flight index in a plain index scan too. >>> >> >> Arrg - misread the planner output....in 9.2 what changes is a plan that >> uses an index scan on the *file_state* index (not >> files_in_flight)...which appears much faster than the bitmap scan on >> file_state. Apologies for the confusion. >> >> I'm thinking that I'm seeing the effect Tom has just mentioned. > > It's not using a bitmapscan in either case; it's a straight indexscan. > > Right, I suspect that bloating is possibly the significant factor then - can you REINDEX? Cheers Mark
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