Received: from malur.postgresql.org ([217.196.149.56]) by arkaria.postgresql.org with esmtp (Exim 4.84_2) (envelope-from ) id 1b3ADQ-0005un-Qh for pgsql-hackers@arkaria.postgresql.org; Wed, 18 May 2016 22:45:20 +0000 Received: from localhost ([127.0.0.1] helo=postgresql.org) by malur.postgresql.org with smtp (Exim 4.84_2) (envelope-from ) id 1b3ADP-0000Um-VE for pgsql-hackers@arkaria.postgresql.org; Wed, 18 May 2016 22:45:20 +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 ) id 1b3AC3-0007LF-Mw for pgsql-hackers@postgresql.org; Wed, 18 May 2016 22:43:55 +0000 Received: from out5-smtp.messagingengine.com ([66.111.4.29]) by makus.postgresql.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA384:256) (Exim 4.84_2) (envelope-from ) id 1b3AC0-00005B-WD for pgsql-hackers@postgresql.org; Wed, 18 May 2016 22:43:54 +0000 Received: from compute3.internal (compute3.nyi.internal [10.202.2.43]) by mailout.nyi.internal (Postfix) with ESMTP id 586EE21EBC for ; Wed, 18 May 2016 18:43:51 -0400 (EDT) Received: from frontend2 ([10.202.2.161]) by compute3.internal (MEProxy); Wed, 18 May 2016 18:43:51 -0400 DKIM-Signature: v=1; a=rsa-sha1; c=relaxed/relaxed; d= messagingengine.com; h=cc:content-type:date:from:in-reply-to :message-id:mime-version:references:subject:to:x-sasl-enc :x-sasl-enc; s=smtpout; bh=mQKDzg8NnI0/iGtL0PMNbLsP8Gw=; b=re/+o X2401ow8wYON92o8vFgHtn2fppJS7x1CHJvYSwE1MbD5EK14NIHdhxyDyAUNcYOk EoTgcMcChUJv6eoQmpVT/oa21Uk3bfUP5GUcF6eta0myqEUEO7pa1/ILUGcVw2wZ cq2E59LrwV0x33KO1L5qLS+iuFYqdts15uJtjs= X-Sasl-enc: RWXkh0nIWm+pBfgiJv3U0Cgc9eK3tOoiQvhwe65c88// 1463611430 Received: from intern.anarazel.de (cpe940c6db3bcf1-cm84948c2dbb10.cpe.net.cable.rogers.com [99.241.201.91]) by mail.messagingengine.com (Postfix) with ESMTPA id EC49F6800BD; Wed, 18 May 2016 18:43:50 -0400 (EDT) Date: Wed, 18 May 2016 15:43:48 -0700 From: Andres Freund To: Tom Lane Cc: Josh berkus , Peter Geoghegan , Jeff Janes , Joe Conway , Victor Yegorov , Robert Haas , "pgsql-hackers@postgresql.org" Subject: Re: Reviewing freeze map code Message-ID: <20160518224348.2psbzfen2xqros3a@alap3.anarazel.de> References: <573C77AF.8030201@joeconway.com> <573CCB9C.50705@agliodbs.com> <15044.1463610339@sss.pgh.pa.us> <20160518223436.w32fzgoui6gaaj4p@alap3.anarazel.de> <15161.1463611336@sss.pgh.pa.us> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <15161.1463611336@sss.pgh.pa.us> X-Pg-Spam-Score: -2.6 (--) 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 On 2016-05-18 18:42:16 -0400, Tom Lane wrote: > Andres Freund writes: > > On 2016-05-18 18:25:39 -0400, Tom Lane wrote: > >> Yes, I've been wondering that too. VACUUM is not meant as a corruption > >> checker, and should not be made into one, so what is the point of this > >> flag exactly? > > > Well, so far a VACUUM FREEZE (or just setting vacuum_freeze_table_age = > > 0) verified the correctness of the visibility map; and that found a > > number of bugs. Now visibilitymap grew additional responsibilities, > > with a noticeable risk of data eating bugs, and there's no way to verify > > whether visibilitymap's frozen bits are set correctly. > > Meh. I'm not sure we should grow a rather half-baked feature we'll never > be able to remove as a substitute for a separate sanity checker. The > latter is really the right place for this kind of thing. It's not a new feature, it's a feature we removed as a side effect. And one that allows us to evaluate whether the new feature actually works. -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers