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[78.45.216.26]) by smtp.gmail.com with ESMTPSA id u202sm17512071wmd.24.2016.03.22.06.49.18 (version=TLSv1/SSLv3 cipher=OTHER); Tue, 22 Mar 2016 06:49:19 -0700 (PDT) Subject: Re: multivariate statistics v14 To: Tatsuo Ishii References: <89341a68-4729-ad28-bb39-cef31849aedb@2ndquadrant.com> <20160322.194101.1823396309134293700.t-ishii@sraoss.co.jp> <10036d4a-f52d-6366-1251-367ba2cf51e9@2ndquadrant.com> <20160322.214615.1524680563827969904.t-ishii@sraoss.co.jp> Cc: jeff.janes@gmail.com, alvherre@2ndquadrant.com, pgsql-hackers@postgresql.org From: Tomas Vondra Message-ID: Date: Tue, 22 Mar 2016 14:49:15 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:46.0) Gecko/20100101 Thunderbird/46.0a2 MIME-Version: 1.0 In-Reply-To: <20160322.214615.1524680563827969904.t-ishii@sraoss.co.jp> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit 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 Hi, On 03/22/2016 01:46 PM, Tatsuo Ishii wrote: ... > Sorry, maybe I did not explain clearly. My question is, if put > patches only 0002 to 0005 into 9.6, does it still give any visible > benefit to users? The users will be able to define statistics with the limitation that only a single one (the one covering the most columns referenced by the clauses) can be used when estimating a query. Which is not perfect, but I think it's a valuable improvement. It might also be possible to split 0006 into smaller pieces, for example implementing the "non-overlapping statistics" case first and then extending it to more complicated cases. That might increase the change of getting at least some of that into 9.6 ... But considering it's not clear whether the initial chunks are likely to make it into 9.6 - I kinda expect a fair amount of comments from TL about the preceding parts, who mentioned he might look at the patch this week. So I'm not sure splitting 0006 into smaller pieces makes sense at this point. regards -- Tomas Vondra http://www.2ndQuadrant.com PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers