Re: Compressing the AFTER TRIGGER queue

On Mon, Aug 1, 2011 at 1:42 PM, Dean Rasheed <dean(dot)a(dot)rasheed(at)gmail(dot)com> wrote:
>>> 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?
>
> I thought that only happens after the transaction is committed, and
> old enough, whereas the trigger code only needs to follow the chain in
> the updating transaction.

Hmm, true.

I worry a bit that this might foreclose possible future optimization
of the "self update" case, which is a known pain point. Am I wrong to
worry?

--
Robert Haas
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