Received: from malur.postgresql.org ([217.196.149.56])
	by arkaria.postgresql.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256)
	(Exim 4.92)
	(envelope-from <pgsql-sql-owner+archive@lists.postgresql.org>)
	id 1j85K0-0000LV-Hc
	for pgsql-sql@arkaria.postgresql.org; Sat, 29 Feb 2020 16:50:36 +0000
Received: from localhost ([127.0.0.1] helo=malur.postgresql.org)
	by malur.postgresql.org with esmtp (Exim 4.89)
	(envelope-from <pgsql-sql-owner+archive@lists.postgresql.org>)
	id 1j85Jx-0006Hy-O6
	for pgsql-sql@arkaria.postgresql.org; Sat, 29 Feb 2020 16:50:33 +0000
Received: from makus.postgresql.org ([2001:4800:3e1:1::229])
	by malur.postgresql.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256)
	(Exim 4.89)
	(envelope-from <lists-pgsql@useunix.net>)
	id 1j85Jx-0006Hr-Av
	for pgsql-sql@lists.postgresql.org; Sat, 29 Feb 2020 16:50:33 +0000
Received: from li1929-156.members.linode.com ([172.104.219.156]
 helo=ln-1.useunix.net)
	by makus.postgresql.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256)
	(Exim 4.92)
	(envelope-from <lists-pgsql@useunix.net>)
	id 1j85Jq-0002oD-8V
	for pgsql-sql@lists.postgresql.org; Sat, 29 Feb 2020 16:50:31 +0000
Received: from wcuddy by ln-1.useunix.net with local (Exim 4.92.3)
	(envelope-from <lists-pgsql@useunix.net>)
	id 1j85Jo-0008K0-Uh
	for pgsql-sql@lists.postgresql.org; Sat, 29 Feb 2020 16:50:24 +0000
Date: Sat, 29 Feb 2020 16:50:24 +0000
From: Wayne <lists-pgsql@useunix.net>
To: pgsql-sql@lists.postgresql.org
Subject: min()/max() with BRIN indexes
Message-ID: <20200229165024.GD20190@ln-1.useunix.net>
Mail-Followup-To: pgsql-sql@lists.postgresql.org
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
User-Agent: Mutt/1.10.1 (2018-07-13)
List-Id: <pgsql-sql.lists.postgresql.org>
List-Help: <https://lists.postgresql.org/manage/>
List-Subscribe: <https://lists.postgresql.org/manage/>
List-Post: <mailto:pgsql-sql@lists.postgresql.org>
List-Owner: <mailto:pgsql-sql-owner@lists.postgresql.org>
List-Archive: <https://www.postgresql.org/list/pgsql-sql>
Precedence: bulk

I have rather large tables that use a time stamp as an index. New entries
are continuously added to the table with the current time. If I convert
from BTREE to BRIN indexes and select records with specific date ranges
the BRIN is used and performance is acceptable. However I often want to
get the latest time stamp using the max() function. I didn't expect that
this would result in a sequential scan of the table and skip the BRIN
index.

Is this expected behavior?

Thanks,
Wayne