On Mon, May 12, 2014 at 4:56 PM, Heikki Linnakangas <hlinnakan...@vmware.com> wrote: > On 01/24/2014 02:10 PM, Rajeev rastogi wrote: >> >> We are also planning to implement CSN based snapshot. >> So I am curious to know whether any further development is happening on >> this. > > > I started looking into this, and plan to work on this for 9.5. It's a big > project, so any help is welcome. The design I have in mind is to use the LSN > of the commit record as the CSN (as Greg Stark suggested).
I did do some coding work on this, but the free time I used to work on this basically disappeared with a child in the family. I guess what I have has bitrotted beyond recognition. However I may still have some insight that may be of use. From your comments I presume that you are going with the original, simpler approach proposed by Robert to simply keep the XID-CSN map around for ever and probe it for all visibility lookups that lie outside of the xmin-xmax range? As opposed to the more complex hybrid approach I proposed that keeps a short term XID-CSN map and lazily builds conventional list-of-concurrent-XIDs snapshots for long lived snapshots. I think that would be prudent, as the simpler approach needs mostly the same ground work and if turns out to work well enough, simpler is always better. Regards, Ants Aasma -- Cybertec Schönig & Schönig GmbH Gröhrmühlgasse 26 A-2700 Wiener Neustadt Web: http://www.postgresql-support.de -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
