On Thu, 2008-09-11 at 17:58 +0300, Heikki Linnakangas wrote: > BTW, we haven't talked about how to acquire a snapshot in the slave. > You'll somehow need to know which transactions have not yet committed, > but will in the future. In the master, we keep track of in-progress > transaction in the ProcArray, so I suppose we'll need to do the same > in the slave. Very similar to prepared transactions, actually. I > believe the Abort records, which are not actually needed for normal > operation, become critical here. The slave will need to put an entry > to ProcArray for any new XLogRecord.xl_xid it sees in the WAL, and > remove the entry at a Commit and Abort record. And clear them all at a > shutdown record.
Although I said differently earlier, it seems cleaner to make recovery snapshots work by emulating ProcArray entries as you suggest. Fatal errors were my problem there, but I think that's solvable now. -- Simon Riggs www.2ndQuadrant.com PostgreSQL Training, Services and Support -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
