Message-ID: <43A7EDD5.1080400@p0f.net>
Date: Tue, 20 Dec 2005 12:41:09 +0100
From: Grega Bremec <gregab@p0f.net>
Organization: P0F
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To: PostgreSQL Performance List <pgsql-performance@postgresql.org>
Subject: Re: Read only transactions - Commit or Rollback
References: 
 <16F953410A0F1346848DCB476A989CFE01D6AF@swtexchange2.technology.de>
In-Reply-To: 
 <16F953410A0F1346848DCB476A989CFE01D6AF@swtexchange2.technology.de>
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Nörder-Tuitje wrote:
|> We have a database containing PostGIS MAP data, it is accessed
|> mainly via JDBC. There are multiple simultaneous read-only
|> connections taken from the JBoss connection pooling, and there
|> usually are no active writers. We use connection.setReadOnly(true).
|>
|> Now my question is what is best performance-wise, if it does make
|> any difference at all:
|>
|> Having autocommit on or off? (I presume "off")
|>
|> Using commit or rollback?
|>
|> Committing / rolling back occasionally (e. G. when returning the
|> connection to the pool) or not at all (until the pool closes the
|> connection)?
|>
| afaik, this should be completely neglectable.
|
| starting a transaction implies write access. if there is none, You do
| not need to think about transactions, because there are none.
|
| postgres needs to schedule the writing transactions with the reading
| ones, anyway.
|
| But I am not that performance profession anyway ;-)

Hello, Marcus, Nörder, list.

What about isolation? For several dependent calculations, MVCC doesn't
happen a bit with autocommit turned on, right?

Cheers,
- --
~    Grega Bremec
~    gregab at p0f dot net
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