[Pgpool-general] Multi-statement queries

[Tatsuo Ishii]

Problme is, pgpool-II parses only "statement1" in the case.
Thus if statement1 is a plane SELECT, statement1 to statementN will be
load balanced which will cause problem if one of statements are not
SELECT. This is just an example.
--
Tatsuo Ishii
SRA OSS, Inc. Japan
English: http://www.sraoss.co.jp/index_en.php
Japanese: http://www.sraoss.co.jp

> My experience is also that multi-statement queries ("statement1; statement2; ...; statementN;") work in pgpool-II, so now I'm confused with "pgpool-II cannot process multi-statement query". Also, why wouldn't it work if PostgreSQL itself does? I think the idea is pgpool-II to work transparently as connecting directly to PostgreSQL.
> 
> Daniel
> 
> > -----Original Message-----
> > From: pgpool-general-bounces at pgfoundry.org [mailto:pgpool-general-
> > bounces at pgfoundry.org] On Behalf Of Matthias Tief
> > Sent: Tuesday, March 09, 2010 4:11 AM
> > To: pgpool-general at pgfoundry.org
> > Subject: Re: [Pgpool-general] Multi-statement queries
> > 
> > Thank you for your rapid answer.
> > 
> > But for me it is still not clear. What you describe seems to be a
> > collection of statements transmitted as a single transaction. But this
> > is done very well by pgpool-II in my tests. I am wrong with that?
> > 
> > So than my question is: What is the difference between "multi-statement
> > queries" and a single transaction of multiple statements?
> > 
> > As I understand pgadmin implicitly wrapps a BEGIN/COMMIT block around
> > all statements, that it becomes a single transaction.
> > 
> > Looking forward to your answer.
> > 
> > Matthias
> > 
> > Guillaume Lelarge schrieb:
> > > Le 05/03/2010 09:45, Matthias Tief a écrit :
> > >> Hallo,
> > >>
> > >> we are planning to use pgpool-II as replication solution for our
> > >> PostgeSQL application. Currently we evaluate, whether the
> > restriction of
> > >> pgpool-II affect our application. In the documentation you say:
> > >> "pgpool-II cannot process multi-statement query." What do you
> > exactly
> > >> mean with "multi-statement queries". As I found out you don't mean
> > >> transactions that contain multiple statments, like BEGIN - COMMIT
> > >> blocks. These blocks are "committed" or in case of a failure are
> > "rolled
> > >> back" correctly. I would appreciate if you could give me an example
> > of
> > >> multi-statement queries.
> > >>
> > >
> > > "statement1; statement2; statement3;" in a single trip to the
> > backend.
> > >
> > > For example:
> > >
> > > "INSERT INTO t1 VALUES (1); INSERT INTO t1 VALUES (2); INSERT INTO t1
> > > VALUES (3);"
> > >
> > > is a multi-statement query, whereas
> > >
> > > "INSERT INTO t1 VALUES (1);"
> > > then
> > > "INSERT INTO t1 VALUES (2);"
> > > then
> > > "INSERT INTO t1 VALUES (3);"
> > >
> > > are three one-statement queries.
> > >
> > > pgAdmin uses this quite a lot ("SET client_encoding TO utf8; SELECT *
> > > FROM...").
> > >
> > >
> > 
> > --
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> > Fax: +49 (030) 220791-55
> > Email: matthias.tief at itso-berlin.de
> > Internet: www.itso.de
> > Amtsgericht Berlin Charlottenburg HRB 21013
> > 
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