Andrew Sullivan <ajs@crankycanuck.ca> writes:
> On Wed, Dec 26, 2007 at 05:48:14PM -0800, ivan.hou wrote:
>> if i executed "select * from mydb" twice, the XID wil be increased by 2
> Yep. Whereas if you did
> BEGIN;
> SELECT 1;
> SELECT 1;
> COMMIT;
> the xid would be increased by 1.
But note that as of 8.3, SELECT-only transactions won't acquire an
XID and hence won't advance the counter. So if you're thinking of
writing code that depends on that behavior, don't.
regards, tom lane