DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.com;
	h=Message-ID:Date:From:Subject:To:MIME-Version:Content-Type;
	b=KyCMrMmnuVFi+XFExxTj1/Glen8tDhwFcLtRG4VVKX1WW04jCItH5osbs5K0nM1KI1j9ekMXiPyNvhhLB5SSbyrBrhRIVbzpslsYlZilZN3xldw7SYEnEvjZZl6N12+njWHtdPvYd0hoM/9Q2mPh5OsQFm88XhXlUi6tpIDLV3A=
	;
Message-ID: <20060311010855.4341.qmail@web50314.mail.yahoo.com>
Date: Fri, 10 Mar 2006 17:08:55 -0800 (PST)
From: <ogjunk-pgjedan@yahoo.com>
Subject: READ COMMITTE without START TRANSACTION?
To: pgsql-sql@postgresql.org
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii

Hello,

I need to run some SELECT queries that take a while (10+ minutes) to complete, and I'm wondering about the isolation about the results I get.  More precisely, while my SELECT is running, the DB is being updated by another application, and I am wondering which, if any, data changes my SELECT will see.

Example:
If I start my SELECT at 10:00, and it finishes at 10:10, will my results include data that was inserted between 10:00 and 10:10?
Similarly, will my result include data that was updated between 10:00 and 10:10?
The same question for data that was deleted during that period.

If it matters, my SELECT runs from psql client, while concurrent inserts, updates, and deletes are executed from a separate application (webapp).

For my purposes in this case I need the SELECT to get the results that represent data right at the beginning of the query - a snapshot.  I read this: http://www.postgresql.org/docs/8.1/static/transaction-iso.html  and it looks like this is the default PG behaviour (READ COMMITTED)

Question:
If I do not explicitly START TRANSACTION before the SELECT, will this READ COMMITTED XA behaviour still be in effect?

Thanks,
Otis