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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Stephen Frost <sfrost@snowman.net>
Cc: David G. Johnston <david.g.johnston@gmail.com>
Cc: Thomas Kellerer <shammat@gmx.net>
Cc: pgsql-performance@lists.postgresql.org <pgsql-performance@lists.postgresql.org>
Subject: Re: PostgreSQL does not choose my indexes well
Date: Thu, 23 Apr 2020 16:33:07 -0400
Message-ID: <12000.1587673987@sss.pgh.pa.us> (raw)
In-Reply-To: <20200423200143.GK13712@tamriel.snowman.net>
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	<1bb37a19-77f6-8c49-073e-ed6251c98583@gmx.net>
	<CAKFQuwY9twbudMDvmuo+9Mjy0y-cJcvzPazD07-oB+WV1qOMnA@mail.gmail.com>
	<4315.1587655779@sss.pgh.pa.us>
	<20200423171858.GE13712@tamriel.snowman.net>
	<18681.1587664601@sss.pgh.pa.us>
	<20200423200143.GK13712@tamriel.snowman.net>

Stephen Frost <sfrost@snowman.net> writes:
> I'm pretty suspicious that they've made some odd planner configuration
> changes or something along those lines to end up with the plan they got,
> or there's some reason we don't think we can use the partial index.

Yeah, the latter is definitely a possibility.  I find the apparently
unnecessary cast in the partial-index predicate to be suspicious ---
maybe that's blocking matching to the WHERE clause?  In principle
the useless cast should have gotten thrown away, but maybe what we
were shown isn't quite exactly the real DDL.

			regards, tom lane

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