| From: | Andres Freund <andres(at)anarazel(dot)de> |
|---|---|
| To: | Kevin Grittner <kgrittn(at)gmail(dot)com> |
| Cc: | Robert Haas <robertmhaas(at)gmail(dot)com>, Kevin Grittner <kgrittn(at)postgresql(dot)org>, "pgsql-hackers(at)postgresql(dot)org" <pgsql-hackers(at)postgresql(dot)org>, "pgsql-committers(at)postgresql(dot)org" <pgsql-committers(at)postgresql(dot)org> |
| Subject: | Re: [HACKERS] Re: pgsql: Avoid extra locks in GetSnapshotData if old_snapshot_threshold < |
| Date: | 2016-04-13 21:23:56 |
| Message-ID: | 20160413212356.uv4velailmivnihh@alap3.anarazel.de |
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| Lists: | pgsql-committers pgsql-hackers |
On 2016-04-13 16:05:25 -0500, Kevin Grittner wrote:
> OK, thanks. I can't think of anything else to ask for at this
> point. If you feel that you have enough to press for some
> particular course of action, go for it.
I think we, at the very least, need a clear proposal how to resolve the
scalability issue around OldSnapshotTimeMapLock in 9.6. Personally I
think we shouldn't release with such a large regression due to a
performance oriented feature; but if we do, we need to be confident that
we can easily resolve it for 9.7. In contrast to the spinlock issue I
don't see an easy way unfortunately. Without such a plan it seems too
likely to go unfixed for a long time otherwise.
> Personally, I want to do some more investigation on those big
> machines.
Sounds good, especially around the regression with the feature disabled.
Andres
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