Re: Question about indexes
От | Greg Stark |
---|---|
Тема | Re: Question about indexes |
Дата | |
Msg-id | 87vfmwrtxt.fsf@stark.xeocode.com обсуждение исходный текст |
Ответ на | Question about indexes (Greg Stark <gsstark@mit.edu>) |
Ответы |
Re: Question about indexes
Re: Question about indexes |
Список | pgsql-hackers |
Tom Lane <tgl@sss.pgh.pa.us> writes: > In any case, this discussion is predicated on the assumption that the > operations involving the bitmap are a significant fraction of the total > time, which I think is quite uncertain. Until we build it and profile > it, we won't know that. The other thought I had was that it would be difficult to tell when to follow this path. Since the main case where it wins is when the individual indexes aren't very selective but the combination is very selective, and we don't have inter-column correlation statistics ... -- greg
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