Re: Proposal for CSN based snapshots - Mailing list pgsql-hackers

From Jeff Davis
Subject Re: Proposal for CSN based snapshots
Date
Msg-id 1409116988.2335.463.camel@jeff-desktop
Whole thread Raw
In response to Re: Proposal for CSN based snapshots  (Heikki Linnakangas <hlinnakangas@vmware.com>)
Responses Re: Proposal for CSN based snapshots
List pgsql-hackers
On Tue, 2014-08-26 at 13:45 +0300, Heikki Linnakangas wrote:
> Yeah. This patch in the current state is likely much much slower than 
> unpatched master, except in extreme cases where you have thousands of 
> connections and short transactions so that without the patch, you spend 
> most of the time acquiring snapshots.

What else are you looking to accomplish with this patch during this
'fest? Bug finding? Design review? Performance testing?

I haven't had a good track record with my performance testing recently,
so I'm unlikely to be much help there.

It seems a bit early for bug hunting, unless you think it will raise
possible design issues.

I think there's already at least one design issue to consider, which is
whether we care about CLOG/CSNLOG access for hinted records where the
xid > snapshot->xmin (that is, accesses that previously would have
looked at xip). Would more discussion help here or do we need to wait
for performance numbers?

Regards,Jeff Davis





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