From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
---|---|
To: | Jeff Frost <jeff(at)frostconsultingllc(dot)com> |
Cc: | Andrew Sullivan <ajs(at)crankycanuck(dot)ca>, pgsql-admin(at)postgresql(dot)org |
Subject: | Re: What's the XID? |
Date: | 2007-12-27 17:55:24 |
Message-ID: | 17845.1198778124@sss.pgh.pa.us |
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Lists: | pgsql-admin |
Jeff Frost <jeff(at)frostconsultingllc(dot)com> writes:
> On Thu, 27 Dec 2007, Tom Lane wrote:
>> 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.
> So, the new XID counter won't advance unless there's at least one
> INSERT/UPDATE/DELETE in the transaction? Does it also update for SELECTs that
> call a function which does some write activity?
Any "write" activity causes an XID to be acquired.
> Is there a new counter (or old one that I don't know about) that keeps track
> of the SELECT-only transactions?
There's no global counter. There's a backend-local "virtual transaction
id" counter.
regards, tom lane
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