| From: | Noah Misch <noah(at)leadboat(dot)com> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | Andrew Gierth <andrew(at)tao11(dot)riddles(dot)org(dot)uk>, Heikki Linnakangas <hlinnakangas(at)vmware(dot)com>, Josh Berkus <josh(at)agliodbs(dot)com>, Andres Freund <andres(at)2ndquadrant(dot)com>, Greg Sabino Mullane <greg(at)turnstep(dot)com>, Marti Raudsepp <marti(at)juffo(dot)org>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>, Tomas Vondra <tv(at)fuzzy(dot)cz>, Atri Sharma <atri(dot)jiit(at)gmail(dot)com> |
| Subject: | Re: Final Patch for GROUPING SETS |
| Date: | 2014-12-23 07:29:58 |
| Message-ID: | 20141223072958.GB1900132@tornado.leadboat.com |
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| Lists: | pgsql-hackers |
On Mon, Dec 22, 2014 at 10:46:16AM -0500, Tom Lane wrote:
> I still find the ChainAggregate approach too ugly at a system structural
> level to accept, regardless of Noah's argument about number of I/O cycles
> consumed. We'll be paying for that in complexity and bugs into the
> indefinite future, and I wonder if it isn't going to foreclose some other
> "performance opportunities" as well.
Among GROUPING SETS GroupAggregate implementations, I bet there's a nonempty
intersection between those having maintainable design and those having optimal
I/O usage, optimal memory usage, and optimal number of sorts. Let's put more
effort into finding it. I'm hearing that the shared tuplestore is
ChainAggregate's principal threat to system structure; is that right?
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