Received: from malur.postgresql.org ([217.196.149.56])
	by arkaria.postgresql.org with esmtps
 (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA384:256)
	(Exim 4.89)
	(envelope-from <pgsql-performance-owner+archive@lists.postgresql.org>)
	id 1exwoV-000426-MC
	for pgsql-performance@arkaria.postgresql.org; Mon, 19 Mar 2018 15:35:07 +0000
Received: from localhost ([127.0.0.1] helo=malur.postgresql.org)
	by malur.postgresql.org with esmtp (Exim 4.89)
	(envelope-from <pgsql-performance-owner+archive@lists.postgresql.org>)
	id 1exwoU-0002zp-BJ
	for pgsql-performance@arkaria.postgresql.org; Mon, 19 Mar 2018 15:35:06 +0000
Received: from magus.postgresql.org ([2a02:c0:301:0:ffff::29])
	by malur.postgresql.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA384:256)
	(Exim 4.89)
	(envelope-from <tgl@sss.pgh.pa.us>)
	id 1exwoU-0002ze-3i
	for pgsql-performance@lists.postgresql.org; Mon, 19 Mar 2018 15:35:06 +0000
Received: from sss.pgh.pa.us ([66.207.139.130])
	by magus.postgresql.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA384:256)
	(Exim 4.89)
	(envelope-from <tgl@sss.pgh.pa.us>)
	id 1exwoQ-0000cn-Vm
	for pgsql-performance@postgresql.org; Mon, 19 Mar 2018 15:35:05 +0000
Received: from sss1.sss.pgh.pa.us (localhost [127.0.0.1])
	by sss.pgh.pa.us (8.14.4/8.14.4) with ESMTP id w2JFZ0Z3031891;
	Mon, 19 Mar 2018 11:35:00 -0400
From: Tom Lane <tgl@sss.pgh.pa.us>
To: David Osborne <david@qcode.co.uk>
cc: pgsql-performance@postgresql.org
Subject: Re: Slow performance after restoring a dump
In-reply-to: 
 <CAKmpXCfZUyTwOT3m0HF+uAGbjHt9GHHvhP4jty6QJQLU4Ag8Dw@mail.gmail.com>
References: 
 <CAKmpXCfZUyTwOT3m0HF+uAGbjHt9GHHvhP4jty6QJQLU4Ag8Dw@mail.gmail.com>
Comments: In-reply-to David Osborne <david@qcode.co.uk>
	message dated "Mon, 19 Mar 2018 15:13:37 -0000"
MIME-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-ID: <31889.1521473700.1@sss.pgh.pa.us>
Date: Mon, 19 Mar 2018 11:35:00 -0400
Message-ID: <31890.1521473700@sss.pgh.pa.us>
List-Id: <pgsql-performance.lists.postgresql.org>
List-Help: <https://lists.postgresql.org/manage/>
List-Subscribe: <https://lists.postgresql.org/manage/>
List-Post: <mailto:pgsql-performance@lists.postgresql.org>
List-Owner: <mailto:pgsql-performance-owner@lists.postgresql.org>
List-Archive: <https://www.postgresql.org/list/pgsql-performance>
Precedence: bulk

David Osborne <david@qcode.co.uk> writes:
> Hi, I was wondering if someone could help us work out why this query is so
> slow.
> We've just dumped a database (Postgresql 9.1) and restored it to a new
> instance (AWS RDS 9.6) (via pg_dump, restored to psql)

The first question people will ask is did you re-ANALYZE the new
database?  pg_dump doesn't take care of that for you, and auto-analyze
might not think it needs to process the smaller tables.

			regards, tom lane