Received: from malur.postgresql.org ([217.196.149.56]) by arkaria.postgresql.org with esmtp (Exim 4.84_2) (envelope-from ) id 1bXW0r-0002sZ-T7 for pgsql-hackers@arkaria.postgresql.org; Wed, 10 Aug 2016 16:05:50 +0000 Received: from localhost ([127.0.0.1] helo=postgresql.org) by malur.postgresql.org with smtp (Exim 4.84_2) (envelope-from ) id 1bXW0r-00036b-CX for pgsql-hackers@arkaria.postgresql.org; Wed, 10 Aug 2016 16:05:49 +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 4.84_2) (envelope-from ) id 1bXVzU-0001VD-RA for pgsql-hackers@postgresql.org; Wed, 10 Aug 2016 16:04:24 +0000 Received: from tamriel.snowman.net ([2001:4830:167b::11]) by magus.postgresql.org with esmtp (Exim 4.84_2) (envelope-from ) id 1bXVzR-0007kr-5L for pgsql-hackers@postgresql.org; Wed, 10 Aug 2016 16:04:24 +0000 Received: by tamriel.snowman.net (Postfix, from userid 1000) id AEF135F7A0; Wed, 10 Aug 2016 12:04:19 -0400 (EDT) Date: Wed, 10 Aug 2016 12:04:19 -0400 From: Stephen Frost To: "Joshua D. Drake" Cc: Robert Haas , Heikki Linnakangas , Tom Lane , Alexander Korotkov , Simon Riggs , Dilip Kumar , Jeff Davis , PostgreSQL-development , Alvaro Herrera , Greg Stark , Andres Freund , Rajeev rastogi , Markus Wanner , Ants Aasma , Bruce Momjian , obartunov , Teodor Sigaev Subject: Re: Proposal for CSN based snapshots Message-ID: <20160810160419.GH4028@tamriel.snowman.net> References: <69041c5a-ec60-3c54-49d0-5df071b27f52@iki.fi> <79213506-4c9c-7e7a-44c6-ae94484c1159@iki.fi> <6906.1470840684@sss.pgh.pa.us> <8c150c9d-6ba2-69fd-e908-ed2fc2775c05@iki.fi> <3406288c-9989-5c95-4445-5443b7a7b66f@commandprompt.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="aSoblPWN/K2Aktn9" Content-Disposition: inline In-Reply-To: <3406288c-9989-5c95-4445-5443b7a7b66f@commandprompt.com> X-Editor: Vim http://www.vim.org/ X-Info: http://www.snowman.net X-Operating-System: Linux/3.13.0-91-generic (x86_64) X-Uptime: 11:59:35 up 32 days, 17:23, 9 users, load average: 0.00, 0.04, 0.05 User-Agent: Mutt/1.5.21 (2010-09-15) X-Pg-Spam-Score: -2.4 (--) List-Archive: List-Help: List-ID: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: X-Mailing-List: pgsql-hackers Precedence: bulk Sender: pgsql-hackers-owner@postgresql.org --aSoblPWN/K2Aktn9 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline * Joshua D. Drake (jd@commandprompt.com) wrote: > +1 for Robert here, removing async commit is a non-starter. It is > PostgreSQL performance 101 that you disable synchronous commit > unless you have a specific data/business requirement that needs it. > Specifically because of how much faster Pg is with async commit. I agree that we don't want to get rid of async commit, but, for the archive, I wouldn't recommend using it unless you specifically understand and accept that trade-off, so I wouldn't lump it into a "PostgreSQL performance 101" group- that's increasing work_mem, shared_buffers, WAL size, etc. Accepting that you're going to lose *committed* transactions on a crash requires careful thought and consideration of what you're going to do when that happens, not the other way around. Thanks! Stephen --aSoblPWN/K2Aktn9 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQIcBAEBCgAGBQJXq1CDAAoJEO1sijiDR2RVpjEQALRn2du04gAMUoBEShwFEXH7 4aaWW2OTveAAliKJ8pDSS/oF63kpuUheuKiqrnuCGGg24JIXg6v3uJofJ7neyt6r we/+Me0HlTfe4eCII9hQcqfS7Szb3Jhpr6RG8MZPuiRST47UVDj59mz7zGQKR033 AAecC7ju5W5cIHR+VGpWUsxKlA8S0sVZxxkbX0L47R+zr+UtvUxpJPvUPTobfTt2 gra7+R6uUM9NClQFCm+5KadO5/bXFlJpCd1iYqXww+70SnG2ElREYvoF7++Rdloh wxZyeAOtb4C8xXkWkKEkgEO7hRQeJG0iGyx0p4dnm6+4qOnSho+bTj+Wt4kbRVIe NV1RiHP/VqqMsTsWo1egkkDCiCef/RbHAfJ1HmRG6CgL4DOLCO64yOph6p+Q8y+R +FPHwUEHvjicW2ePyaOt7d6rywRhMcbIXGVY/IUIVbSmOFs4HkxTFJYrkmqxrRsp i8KuSDeH9wNRdP3n2PmePk6U0b8wMvXcM4gQg1Lvra0N+tAcd8Vq85/ToNy6TJoG LoaT7IImxmY+Zy4QrkBXSFeJoKFr/bdaB4IsH7MYwONXrq4LjUurIxdVAZpQ4vb6 O4FdFar8t11MWf5M8RZVblYUxNuzPtu/WEkGtZU9QZNs4+IZbYebHwdQ6YufbZ+v gC6wyPdAHm7xnJ4ZEn0x =yOev -----END PGP SIGNATURE----- --aSoblPWN/K2Aktn9--