Re: Uh, I change my mind about commit_delay + commit_siblings (sort of)

On Thu, May 31, 2012 at 6:19 AM, Simon Riggs <simon(at)2ndquadrant(dot)com> wrote:
> I've looked at this more closely now and I can see that the call to
> XLogFlush() that is made from xact_redo_commit_internal() doesn't ever
> actually flush WAL, so whether we delay or not is completely
> irrelevant.
>
> So un-agreed. No change required to patch there.

I think Peter's suggestion of forcibly setting the delay to 0 in the
startup process is a good one, though. It's one line of code, and if
it isn't strictly necessary today, it still seems like good
future-proofing.

I am not very happy about the idea of renaming commit_* to
group_commit_*. It's basically a cosmetic renaming, and breaking
existing configuration files for cosmetic purposes does not seem
warranted to me, especially when the old and new names are so close.
I certainly don't think we can do that in 9.2, now that beta1 has
already shipped. Modifying the default contents of postgresql.conf
after we've shipped beta has been a historical no-no for reasons that
escape me at the moment, but IIRC they're not stupid reasons.

Frankly, I think this whole thing should be pushed to 9.3. The
commit_delay and commit_siblings knobs suck, but they've sucked for a
long time, and it won't kill anybody to wait another release cycle to
fix them. We have plenty of more important things queued up for 9.3
already, and I don't believe there's any compelling reason to think
that this particular thing needs preferential treatment.

--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company