| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Andres Freund <andres(at)anarazel(dot)de> |
| Cc: | Tiffany Thang <tiffanythang(at)gmail(dot)com>, "pgsql-generallists(dot)postgresql(dot)org" <pgsql-general(at)lists(dot)postgresql(dot)org> |
| Subject: | Re: multiple indexes on the same column |
| Date: | 2019-04-12 17:07:36 |
| Message-ID: | 2157.1555088856@sss.pgh.pa.us |
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| Thread: | |
| Lists: | pgsql-general |
Andres Freund <andres(at)anarazel(dot)de> writes:
> On 2019-04-12 09:51:51 -0400, Tom Lane wrote:
>> Tiffany Thang <tiffanythang(at)gmail(dot)com> writes:
>>> Can someone explain the use of creating multiple indexes on the same
>>> column?
>> There is none, unless the indexes have different properties (e.g.
>> different opclasses and/or index AMs).
> Well, it can be beneficial to create a new index concurrently, and then
> drop the old one concurrently.
Right, but in that situation there's no intent to keep both indexes
in place. You're just putting up with extra overhead temporarily
as a means to avoid taking an exclusive lock.
regards, tom lane
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