Looking at a VACUUM's WAL records makes me think twice about the way we issue a VACUUM.
1. First we scan the heap, issuing a HEAP2 clean record for every block that needs cleaning. 2. Then we scan the index, issuing WAL records as appropriate. 3. Then we rescan the heap, issuing a HEAP2 clean record for every block. I don't see a reason why we would issue 2 WAL records per block for a VACUUM, nor why we would prune and remove in two steps, dirtying the block each time. Seems like we could write approximately half the amount of data that we do. Surely we can come up with a better plan than that one? -- 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
