On Tue, Aug 9, 2016 at 3:16 PM, Heikki Linnakangas <hlinnaka@iki.fi> wrote:
(Reviving an old thread)
I spent some time dusting off this old patch, to implement CSN snapshots. Attached is a new patch, rebased over current master, and with tons of comments etc. cleaned up. There's more work to be done here, I'm posting this to let people know I'm working on this again. And to have a backup on the 'net :-).
Great! It's very nice seeing that you're working on this patch.
After PGCON I've your patch rebased to the master, but you already did much more.
I switched to using a separate counter for CSNs. CSN is no longer the same as the commit WAL record's LSN. While I liked the conceptual simplicity of CSN == LSN a lot, and the fact that the standby would see the same commit order as master, I couldn't figure out how to make async commits to work.
I didn't get async commits problem at first glance. AFAICS, the difference between sync commit and async is only that async commit doesn't wait WAL log to flush. But async commit still receives LSN.
Could you describe it in more details?
------ Alexander Korotkov Postgres Professional: http://www.postgrespro.com The Russian Postgres Company
