Received: from magus.postgresql.org ([2a02:c0:301:0:ffff::29]) by malur.postgresql.org with esmtp (Exim 4.72) (envelope-from ) id 1T22ql-000454-Sn for pgsql-performance@postgresql.org; Thu, 16 Aug 2012 16:23:11 +0000 Received: from momjian.us ([72.94.173.45]) by magus.postgresql.org with esmtp (Exim 4.72) (envelope-from ) id 1T22qf-0002QE-Uw for pgsql-performance@postgresql.org; Thu, 16 Aug 2012 16:23:11 +0000 Received: from bruce by momjian.us with local (Exim 4.72) (envelope-from ) id 1T22qd-0000zz-VY; Thu, 16 Aug 2012 12:23:03 -0400 Date: Thu, 16 Aug 2012 12:23:03 -0400 From: Bruce Momjian To: "anarazel@anarazel.de" Cc: Ondrej =?utf-8?Q?Ivani=C4=8D?= , J Ramesh Kumar , pgsql-performance@postgresql.org Subject: Re: High Disk write and space taken by PostgreSQL Message-ID: <20120816162303.GC8359@momjian.us> References: <502C6AD5.4070407@oneit.com.au> <20120816145321.GA8359@momjian.us> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/1.5.20 (2009-06-14) X-Pg-Spam-Score: -1.9 (-) X-Archive-Number: 201208/108 X-Sequence-Number: 47646 On Thu, Aug 16, 2012 at 06:07:26PM +0200, anarazel@anarazel.de wrote: > > > Bruce Momjian schrieb: > > >On Thu, Aug 16, 2012 at 03:48:57PM +1000, Ondrej Ivanič wrote: > >> Hi, > >> > >> On 16 August 2012 15:40, J Ramesh Kumar > >wrote: > >> > As you said, MySQL with MyISAM is better choice for my app. Because > >I don't > >> > need transaction/backup. May be I'll try with InnoDB and find the > >disk > >> > write/space difference. Is there any similar methods available in > >postgresql > >> > like MyISAM engine ? > >> > >> You can try unlogged tables: > >> http://www.postgresql.org/docs/9.1/static/sql-createtable.html > >> > >> If specified, the table is created as an unlogged table. Data written > >> to unlogged tables is not written to the write-ahead log (see Chapter > >> 29), which makes them considerably faster than ordinary tables. > >> However, they are not crash-safe: an unlogged table is automatically > >> truncated after a crash or unclean shutdown. The contents of an > >> unlogged table are also not replicated to standby servers. Any > >indexes > >> created on an unlogged table are automatically unlogged as well; > >> however, unlogged GiST indexes are currently not supported and cannot > >> be created on an unlogged table. > > > >I would set full_page_writes = off too. > Why? There shouldn't be any such writes on unlogged tables. True. I was thinking more of the logged tables, and the system tables. -- Bruce Momjian http://momjian.us EnterpriseDB http://enterprisedb.com + It's impossible for everything to be true. +