X-Original-To: pgsql-hackers-postgresql.org@localhost.postgresql.org Received: from localhost (av.hub.org [200.46.204.144]) by svr1.postgresql.org (Postfix) with ESMTP id 21DFBD8377 for ; Tue, 13 Sep 2005 21:42:00 -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 28988-01 for ; Wed, 14 Sep 2005 00:41:50 +0000 (GMT) Received: from xproxy.gmail.com (xproxy.gmail.com [66.249.82.192]) by svr1.postgresql.org (Postfix) with ESMTP id 70D43D81CE for ; Tue, 13 Sep 2005 21:41:51 -0300 (ADT) Received: by xproxy.gmail.com with SMTP id i27so24234wxd for ; Tue, 13 Sep 2005 17:41:56 -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:in-reply-to:mime-version:content-type:references; b=EAtBBrHTUQCCewm9OsCp30wO1WYJlopr3scMH+LwOb94uT+wxVDvGA915kK/JXPT8BHX27HEcVJe+HA0FP4qwqyNtQ6mfOxi8q7FHB2Cd+dVhFeJXnmwCMqKkjNnoOF+yn+E4rGCDcLp8y79qCJxGBsqrF9UFbpO9lgVxfOW3yg= Received: by 10.70.40.14 with SMTP id n14mr6030wxn; Tue, 13 Sep 2005 17:41:56 -0700 (PDT) Received: by 10.70.18.3 with HTTP; Tue, 13 Sep 2005 17:41:55 -0700 (PDT) Message-ID: Date: Tue, 13 Sep 2005 21:41:56 -0300 From: Pryscila B Guttoski Reply-To: pryscila.lista@gmail.com To: pgsql-hackers@postgresql.org Subject: About method of PostgreSQL's Optimizer In-Reply-To: Mime-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_Part_28551_10923804.1126658516010" References: X-Virus-Scanned: by amavisd-new at hub.org X-Spam-Status: No, hits=0.835 required=5 tests=[AWL=0.672, HTML_00_10=0.138, HTML_MESSAGE=0.001, RCVD_BY_IP=0.024] X-Spam-Level: X-Archive-Number: 200509/632 X-Sequence-Number: 73029 ------=_Part_28551_10923804.1126658516010 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_28551_10923804.1126658516010 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.
 ------=_Part_28551_10923804.1126658516010--