Tom Lane wrote:
> Heikki Linnakangas <heikki(at)enterprisedb(dot)com> writes:
>> I was about to resubmit the phantom command ids patch for review, as I
>> noticed a little problem.
>> In fmgr.c in record_C_func, we cache the xmin and cmin, and later in
>> lookup_C_func we check that they match to determine if the cached
>> information is still valid. With phantom command ids, the cmin is not
>> valid outside the inserting transaction, which makes it unusable for
>> that purpose.
> I think that actually that's just belt-and-suspenders programming;
> it should be sufficient to compare tuple TID and xmin. AFAICS a single
> transaction cannot fill the same TID twice, since VACUUM would never
> dare remove a tuple entered by a still-in-progress transaction. So the
> cmin check doesn't seem necessary.
We don't currently use tid in the up-to-dateness check. Just Oid, xmin
and cmin. Good point, tid would work. I'll change it do that in the patch.
In response to
pgsql-hackers by date
|Next:||From: korryd||Date: 2007-01-29 16:25:48|
|Subject: shared_preload_libraries support on Win32?|
|Previous:||From: Tom Lane||Date: 2007-01-29 15:42:59|
|Subject: Re: Phantom command ids again |