Re: failing to use index on UNION of matviews (Re: postgresql 10.1 wrong plan in when using partitions bug)

From: Justin Pryzby <pryzby(at)telsasoft(dot)com>
To: Rick Otten <rottenwindfish(at)gmail(dot)com>
Cc: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, PostgreSQL mailing lists <pgsql-performance(at)postgresql(dot)org>
Subject: Re: failing to use index on UNION of matviews (Re: postgresql 10.1 wrong plan in when using partitions bug)
Date: 2018-02-06 18:18:07
Message-ID: 20180206181807.GC32634@telsasoft.com
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On Sun, Feb 04, 2018 at 11:04:56AM -0500, Rick Otten wrote:
> On Sun, Feb 4, 2018 at 10:35 AM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>
> > Rick Otten <rottenwindfish(at)gmail(dot)com> writes:
> > > I'm wrestling with a very similar problem too - except instead of
> > official
> > > partitions I have a views on top of a bunch (50+) of unioned materialized
> > > views, each "partition" with 10M - 100M rows. On 9.6.6 the queries would
> > > use the indexes on each materialized view. On 10.1, every materialized
> > > view is sequence scanned.

I think it'd be useful to see the plan from explain analyze, on both the
"parent" view and a child, with and without SET enable_seqscan=off,

Justin

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