Re: failing to use index on UNION of matviews (Re: postgresql 10.1 wrong plan in when using partitions bug)
Rick Otten <rottenwindfish@gmail.com>
From: Rick Otten <rottenwindfish@gmail.com>
To: Justin Pryzby <pryzby@telsasoft.com>
Cc: Tom Lane <tgl@sss.pgh.pa.us>, PostgreSQL mailing lists <pgsql-performance@postgresql.org>
Date: 2018-02-08T11:04:36Z
Lists: pgsql-performance
> > >> >> Setting enable_seqscan=off takes one of the shorter queries I was working >> with from about 3 minutes to 300ms. This is a comparable performance >> improvement to where I put a materialized view (with indexes) on top of the >> materialized views instead of using a simple view on top of the >> materialized views. I'll have to try it with the query that takes 12 hours. >> >> > The query that takes 12 hours and won't use indexes when I feel it should is a materialized view refresh. When I set it before testing the plan with a simple explain on the query it definitely gets it to use all of the indexes. Does setting something like "enable_seqscan=off" work when I follow it with a "refresh materialized view concurrently" instead of a simple select? I'll try it to see if it helps the refresh time, but I thought I'd ask. (I got pulled into another problem since my last email, so I haven't had a chance to follow up.)