On Thu, Dec 30, 2010 at 9:49 AM, Florian Pflug <f...@phlo.org> wrote: > On Dec30, 2010, at 13:31 , Joachim Wieland wrote: >> We return snapshot information as a chunk of data to the client. At >> the same time however, we set a checksum in shared memory to protect >> against modification of the snapshot. A publishing backend can revoke >> its snapshot by deleting the checksum and a backend that is asked to >> install a snapshot can verify that the snapshot is correct and current >> by calculating the checksum and comparing it with the one in shared >> memory. > > We'd still have to stream these checksums to the standbys though, > or would they be exempt from the checksum checks?
I am not talking about having synchronized snapshots among standby servers at all. I am only proposing a client API that will work for this future idea as well. > I still wonder whether these checks are worth the complexity. I > believe we'd only allow snapshot modifications for read-only queries > anyway, so what point is there in preventing clients from setting > broken snapshots? What's the use case for it? As soon as nobody comes up with a reasonable use case for it, let's aim for the robust version. Joachim -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers