X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org Received: from localhost (av.hub.org [200.46.204.144]) by svr1.postgresql.org (Postfix) with ESMTP id D3EF4D8DB3 for ; Tue, 13 Sep 2005 19:50:44 -0300 (ADT) Received: from svr1.postgresql.org ([200.46.204.71]) by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) with ESMTP id 02446-02 for ; Tue, 13 Sep 2005 22:50:40 +0000 (GMT) Received: from xproxy.gmail.com (xproxy.gmail.com [66.249.82.201]) by svr1.postgresql.org (Postfix) with ESMTP id 2FAC8D8DA0 for ; Tue, 13 Sep 2005 19:50:39 -0300 (ADT) Received: by xproxy.gmail.com with SMTP id h27so9623wxd for ; Tue, 13 Sep 2005 15:50:42 -0700 (PDT) DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=beta; d=gmail.com; h=received:message-id:date:from:reply-to:to:subject:mime-version:content-type; b=QEj7U1VA6+ivOGz8h+YSEsgSov6pLPheLIf697WX3Qlt/Xr6yOQ412BPH7nqXUqbedIPXKQoOLCn2aNUMJuNRgEXyf01JrmRwAMn0MIT6FFW1mmi05+3trg5bXW7pk4xlzkug5CYyOV9WgbX54PsFjm8eFpHn+zGD61cG7+Djao= Received: by 10.70.30.9 with SMTP id d9mr41716wxd; Tue, 13 Sep 2005 15:50:42 -0700 (PDT) Received: by 10.70.18.3 with HTTP; Tue, 13 Sep 2005 15:50:42 -0700 (PDT) Message-ID: Date: Tue, 13 Sep 2005 19:50:42 -0300 From: Pryscila B Guttoski Reply-To: pryscila.lista@gmail.com To: pgsql-performance@postgresql.org Subject: About method of PostgreSQL's Optimizer Mime-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_Part_28033_21851233.1126651842832" X-Virus-Scanned: by amavisd-new at hub.org X-Spam-Status: No, hits=1.995 required=5 tests=[HTML_00_10=0.138, HTML_MESSAGE=0.001, RCVD_BY_IP=0.024, RCVD_IN_BL_SPAMCOP_NET=1.832] X-Spam-Level: * X-Archive-Number: 200509/176 X-Sequence-Number: 14484 ------=_Part_28033_21851233.1126651842832 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Content-Disposition: inline Hello all! On my master course, I'm studying the PostgreSQL's optimizer. I don't know if anyone in this list have been participated from the=20 PostgreSQL's Optimizer development, but maybe someone can help me on this= =20 question. PostgreSQL generates all possible plans of executing the query (using an=20 almost exhaustive search), then gives a cost to each plan and finally the= =20 cheapest one is selected for execution. There are other methods for query optimization, one of them is based on pla= n=20 transformations (for example, using A-Star algorithm) instead of plan=20 constructions used by PostgreSQL.=20 Does anyone know why this method was choosen? Are there any papers or=20 researches about it? Thank's a lot, Pryscila. ------=_Part_28033_21851233.1126651842832 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Content-Disposition: inline Hello all!

On my master course, I'm studying the PostgreSQL's optimizer.
I don't know if anyone in this list have been participated from the PostgreSQL's Optimizer development, but maybe someone can help me on this question.
PostgreSQL generates all possible plans of executing the query (using an almost exhaustive search), then gives a cost to each plan and finally the cheapest one is selected for execution.
There are other methods for query optimization, one of them is based on plan transformations (for example, using A-Star algorithm) instead of plan constructions used by PostgreSQL.
Does anyone know why this method was choosen? Are there any papers or resea= rches about it?

Thank's a lot,
Pryscila.
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