Received: from maia.hub.org (maia-2.hub.org [200.46.204.251]) by mail.postgresql.org (Postfix) with ESMTP id 2BD091337B53 for ; Tue, 28 Sep 2010 16:15:01 -0300 (ADT) Received: from mail.postgresql.org ([200.46.204.86]) by maia.hub.org (mx1.hub.org [200.46.204.251]) (amavisd-maia, port 10024) with ESMTP id 73077-01 for ; Tue, 28 Sep 2010 19:14:54 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.7.6 Received: from exprod7og124.obsmtp.com (exprod7og124.obsmtp.com [64.18.2.26]) by mail.postgresql.org (Postfix) with SMTP id 5EC321337B3E for ; Tue, 28 Sep 2010 16:14:52 -0300 (ADT) Received: from source ([209.85.215.51]) by exprod7ob124.postini.com ([64.18.6.12]) with SMTP ID DSNKTKI+lIUQ5NduPHR2/s8WA8k7iWyFMNiV@postini.com; Tue, 28 Sep 2010 12:14:54 PDT Received: by mail-ew0-f51.google.com with SMTP id 21so2687150ewy.24 for ; Tue, 28 Sep 2010 12:14:28 -0700 (PDT) Received: by 10.213.42.72 with SMTP id r8mr605016ebe.86.1285701267676; Tue, 28 Sep 2010 12:14:27 -0700 (PDT) Received: from [192.168.1.113] (dsl-hkibrasgw2-ff7ac300-240.dhcp.inet.fi [88.195.122.240]) by mx.google.com with ESMTPS id z55sm10937942eeh.21.2010.09.28.12.14.23 (version=TLSv1/SSLv3 cipher=RC4-MD5); Tue, 28 Sep 2010 12:14:24 -0700 (PDT) Message-ID: <4CA23E8E.6070309@enterprisedb.com> Date: Tue, 28 Sep 2010 22:14:22 +0300 From: Heikki Linnakangas User-Agent: Mozilla/5.0 (X11; U; Linux i686; fi-FI; rv:1.9.1.10) Gecko/20100619 Iceowl/1.0b1 Icedove/3.0.5 MIME-Version: 1.0 To: Robert Haas CC: SAKAMOTO Masahiko , Itagaki Takahiro , pgsql-hackers@postgresql.org Subject: Re: patch: SQL/MED(FDW) DDL References: <4C905DB0.6040302@oss.ntt.co.jp> <4C934741.4070102@oss.ntt.co.jp> <4C9C6B86.3040102@enterprisedb.com> <4CA03EBA.4010203@oss.ntt.co.jp> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Virus-Scanned: Maia Mailguard 1.0.1 X-Spam-Status: No, hits=-4.2 tagged_above=-5 required=5 tests=BAYES_00=-1.9, RCVD_IN_DNSWL_MED=-2.3 X-Spam-Level: X-Archive-Number: 201009/1990 X-Sequence-Number: 170854 On 09/28/10 17:26, Robert Haas wrote: > First, it seems totally wrong to assume that the same functions and > operators will be defined on the remote side as you have locally; > indeed, for CSV files, you won't have anything defined on the remote > side at all. You need some kind of a discovery mechanism here to > figure out which quals are push-downable. And it should probably be > something generic, not a bunch of hard-wired rules that may or may not > be correct in any particular case. What if the remote side is a > competing database product that doesn't understand X = ANY(Y)? > Second, even if a functions or operators does exist on both sides of > the link, how do you know whether they have compatible semantics? Or side-effects. The SQL/MED specification has "routine mappings" for this purpose. We will need that or something similar. -- Heikki Linnakangas EnterpriseDB http://www.enterprisedb.com