Re: Compressing the AFTER TRIGGER queue

On Mon, Aug 1, 2011 at 1:31 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> Dean Rasheed <dean.a.rasheed@gmail.com> writes:
>> On 1 August 2011 17:49, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>>> Ummm ... I only read the data structure comments, not the code, but I
>>> don't see where you store the second CTID for an update event?
>
>> Ah yes, I forgot to mention that bit. I'm using
>> &(tuple1.t_data->t_ctid) to get the second CTID from the old tuple. Is
>> that safe?
>
> Hmmmm ... not sure.  It seems a bit scary, but on the other hand we
> should be able to assume that the updating subtransaction hasn't been
> rolled back (else surely we shouldn't be firing the trigger).  So in
> principle it seems like the t_ctid link can't have been replaced.
> This will foreclose any ideas about collapsing t_ctid link chains,
> if anyone had it in mind to do that.

Don't we already do that when pruning HOT chains?

--
Robert Haas
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