Received: from malur.postgresql.org ([217.196.149.56])
	by arkaria.postgresql.org with esmtp (Exim 4.84_2)
	(envelope-from
 <pgsql-performance-owner+M54322=pgsql-performance-ar@postgresql.org>)
	id 1bXqNU-0004JE-41
	for pgsql-performance@arkaria.postgresql.org; Thu, 11 Aug 2016 13:50:32 +0000
Received: from localhost ([127.0.0.1] helo=postgresql.org)
	by malur.postgresql.org with smtp (Exim 4.84_2)
	(envelope-from
 <pgsql-performance-owner+M54322=pgsql-performance-ar@postgresql.org>)
	id 1bXqNT-0006YS-IF
	for pgsql-performance@arkaria.postgresql.org; Thu, 11 Aug 2016 13:50:31 +0000
Received: from makus.postgresql.org ([2001:4800:1501:1::229])
	by malur.postgresql.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA384:256)
	(Exim 4.84_2)
	(envelope-from <tgl@sss.pgh.pa.us>)
	id 1bXqNT-0006YM-4O
	for pgsql-performance@postgresql.org; Thu, 11 Aug 2016 13:50:31 +0000
Received: from sss.pgh.pa.us ([66.207.139.130])
	by makus.postgresql.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA384:256)
	(Exim 4.84_2)
	(envelope-from <tgl@sss.pgh.pa.us>)
	id 1bXqNQ-0003Ab-RI
	for pgsql-performance@postgresql.org; Thu, 11 Aug 2016 13:50:29 +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 u7BDoRri029013;
	Thu, 11 Aug 2016 09:50:27 -0400
From: Tom Lane <tgl@sss.pgh.pa.us>
To: Andrey Zhidenkov <andrey.zhidenkov@gmail.com>
cc: pgsql-performance@postgresql.org
Subject: Re: Planner do seq scan on empty master partitioned table
In-reply-to: 
 <CAJw4d1XeSzDVNta2-Omgu5Dp5O50e7D_mUvynsvmn=n+_KdhVw@mail.gmail.com>
References: 
 <CAJw4d1XeSzDVNta2-Omgu5Dp5O50e7D_mUvynsvmn=n+_KdhVw@mail.gmail.com>
Comments: In-reply-to Andrey Zhidenkov <andrey.zhidenkov@gmail.com>
	message dated "Thu, 11 Aug 2016 13:46:47 +0300"
Date: Thu, 11 Aug 2016 09:50:27 -0400
Message-ID: <29012.1470923427@sss.pgh.pa.us>
X-Pg-Spam-Score: -2.4 (--)
List-Archive: <http://archives.postgresql.org/pgsql-performance>
List-Help: <mailto:majordomo@postgresql.org?body=help>
List-ID: <pgsql-performance.postgresql.org>
List-Owner: <mailto:pgsql-performance-owner@postgresql.org>
List-Post: <mailto:pgsql-performance@postgresql.org>
List-Subscribe: <mailto:majordomo@postgresql.org?body=sub%20pgsql-performance>
List-Unsubscribe: 
 <mailto:majordomo@postgresql.org?body=unsub%20pgsql-performance>
X-Mailing-List: pgsql-performance
Precedence: bulk
Sender: pgsql-performance-owner@postgresql.org

Andrey Zhidenkov <andrey.zhidenkov@gmail.com> writes:
> I have a table (registry.entry) which has ~ 100 inherited tables. This
> is a master table and it's empty:

As long as it's empty, a seqscan should be essentially free.  Don't
worry about it.  And definitely don't create indexes, that will just
add cost.

			regards, tom lane


-- 
Sent via pgsql-performance mailing list (pgsql-performance@postgresql.org)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-performance