| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Fabien COELHO <coelho(at)cri(dot)ensmp(dot)fr> |
| Cc: | Michael Paquier <michael(at)paquier(dot)xyz>, hellojo180(at)yahoo(dot)es, PostgreSQL Bugs <pgsql-bugs(at)lists(dot)postgresql(dot)org> |
| Subject: | Re: BUG #15987: Improve REINDEX of all indexes of a table at once |
| Date: | 2019-09-01 15:36:25 |
| Message-ID: | 31841.1567352185@sss.pgh.pa.us |
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| Lists: | pgsql-bugs |
Fabien COELHO <coelho(at)cri(dot)ensmp(dot)fr> writes:
>> I don't quite understand your request. You have REINDEX TABLE which
>> is able to reindex all the indexes of a table one by one, […]
> I understood the request as the scan should be factored out, so that
> reindexing a table with multiple indexes would cost only one seq scan.
I'm not totally convinced that that would be an improvement.
For starters, one would presumably have to divide up maintenance_work_mem
per index, which would be a substantial penalty for some index types.
Also, you'd be creating more randomized I/O on the index-writing side
of the equation (for those index types that write the index during the
scan).
It might net out as a win anyway depending on context, but I don't
think it's as clear-cut as the OP seems to think.
regards, tom lane
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