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Re: Implicit autocommit?

From: Eric Faulhaber <ecf(at)goldencode(dot)com>
To: Oliver Jowett <oliver(at)opencloud(dot)com>
Cc: pgsql-jdbc(at)postgresql(dot)org
Subject: Re: Implicit autocommit?
Date: 2007-07-15 17:34:30
Message-ID: 469A5AA6.3090005@goldencode.com (view raw or flat)
Thread:
Lists: pgsql-jdbc
Oliver Jowett wrote:
> Eric Faulhaber wrote:
>
>> I debugged into the driver and found it was issuing a "BEGIN" to the 
>> backend just before each statement.  Why would it do this with 
>> autocommit disabled?
>
> autocommit on = implicit transaction wrapping each individual 
> statement. In the postgres world, this means "don't use BEGIN/COMMIT 
> at all".
>
> autocommit off = explicit transaction demarcation, the first statement 
> executed starts a new transaction that lasts until rollback()/commit() 
> are called. In the postgres world, this means "use 
> BEGIN/ROLLBACK/COMMIT to demarcate the transaction". So the driver 
> issues a BEGIN to start a new transaction as necessary.
>
> -O
Unless I misunderstand your answer, this suggests that vacuum cannot be 
run via JDBC, since it cannot be run within a transaction block.  It is 
my understanding that autovacuum skips temp tables:

http://archives.postgresql.org/pgsql-general/2007-06/msg01645.php

This is consistent with my experience.  So, how can I vacuum a 
long-lived temp table created with a JDBC connection?

Thanks,
Eric Faulhaber


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