On 27/06/2014 8:20 AM, Alvaro Herrera wrote:
Ryan Johnson wrote:
On 26/06/2014 11:04 PM, Alvaro Herrera wrote:
Ryan Johnson wrote:
As part of a research project, I'm trying to change Read Committed
isolation to use HeapTupleSatisfiesNow rather than acquiring a new
snapshot at every command [1].
Are you aware of this?
commit 813fb0315587d32e3b77af1051a0ef517d187763
Author: Robert Haas <rh...@postgresql.org>
Date: Thu Aug 1 10:46:19 2013 -0400
Remove SnapshotNow and HeapTupleSatisfiesNow.
That would be wonderful news... if snapshots weren't so darned
expensive to create.
I take it you aren't aware of this other effort, either:
http://archives.postgresql.org/message-id/539ad153.9000...@vmware.com
That is good news, though from reading the thread it sounds like proc
array accesses are being exchanged for accesses to an SLRU, so a lot of
lwlock calls will remain. It will definitely help, though. SLRU will get
ex-locked a lot less often, so the main source of contention will be for
the actual lwlock acquire/release operations.
Regards,
Ryan
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