Re: delta relations in AFTER triggers

On Mon, Jun 30, 2014 at 11:03:06AM -0400, Robert Haas wrote:
> On Sat, Jun 28, 2014 at 10:35 AM, Kevin Grittner <kgrittn(at)ymail(dot)com> wrote:
> > David Fetter <david(at)fetter(dot)org> wrote:
> >> On Sat, Jun 21, 2014 at 11:06:26AM -0700, Kevin Grittner wrote:
> >
> >>> Here is v2.
> >
> >> I've taken the liberty of making an extension that uses this.
> >> Preliminary tests indicate a 10x performance improvement over the
> >> user-space hack I did that's similar in functionality.
> >
> > Wow, this goes well beyond what I expected for a review! Thanks!
> >
> > As I said in an earlier post, I think that this is best committed
> > as a series of patches, one for the core portion and one for each
> > PL which implements the ability to use the transition (delta)
> > relations in AFTER triggers. Your extension covers the C trigger
> > angle, and it seems to me to be worth committing to contrib as a
> > sample of how to use this feature in C.
> >
> > It is very encouraging that you were able to use this without
> > touching what I did in core, and that it runs 10x faster than the
> > alternatives before the patch.
> >
> > Because this review advances the patch so far, it may be feasible
> > to get it committed in this CF. I'll see what is needed to get
> > there and maybe have a patch toward that end in a few days. The
> > minimum that would require, IMV, is a plpgsql implementation,
> > moving the new pg_trigger columns to the variable portion of the
> > record so they can be null capable, more docs, and regression
> > tests.
>
> Not to rain on your parade, but this patch hasn't really had a serious
> code review yet. Performance testing is good, but it's not the same
> thing.

Happy to help with that, too.

What I wanted to start with is whether there was even rudimentary
functionality, which I established by writing that extension. I
happened to notice, basically as a sanity check, that doing this via
tuplestores happened, at least in one case, to be quicker than doing
it in user space with temp tables.

Cheers,
David.
--
David Fetter <david(at)fetter(dot)org> http://fetter.org/
Phone: +1 415 235 3778 AIM: dfetter666 Yahoo!: dfetter
Skype: davidfetter XMPP: david(dot)fetter(at)gmail(dot)com
iCal: webcal://www.tripit.com/feed/ical/people/david74/tripit.ics

Remember to vote!
Consider donating to Postgres: http://www.postgresql.org/about/donate