Re: partial indexes and bitmap scans

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Stephen Frost <sfrost(at)snowman(dot)net>
Cc: pgsql-hackers(at)postgresql(dot)org
Subject: Re: partial indexes and bitmap scans
Date: 2017-03-09 16:44:24
Message-ID: 22932.1489077864@sss.pgh.pa.us
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Stephen Frost <sfrost(at)snowman(dot)net> writes:
> Perhaps I'm missing something obvious, but isn't it a bit redundant to
> have both a Recheck condition (which is the predicate of the index) and
> a Filter condition (which is the user's predicate) when we've already
> decided that the user's predicate must result in a subset of the
> index's, as, otherwise, we wouldn't be able to use the index in the
> first place?

Yeah, I think this is just something that the planner doesn't see fit
to expend cycles on detecting.

regards, tom lane

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