Re: What's the XID?

On Thu, 27 Dec 2007, Tom Lane wrote:

> 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.

>
Tom,

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?

Is there a new counter (or old one that I don't know about) that keeps track
of the SELECT-only transactions?


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