On Fri, 2009-01-09 at 18:30 +0200, Heikki Linnakangas wrote: > The hot standby patch has some hacks to decide which full-page-images > can be restored holding an exclusive lock and which ones need a > vacuum-strength lock. It's not very pretty as is, as mentioned in > comments too.
Agreed! > How about we refactor things so that redo-functions are responsible for > calling RestoreBkpBlocks? The redo function can then pass an argument > indicating what kind of lock is required. We should also change > XLogReadBufferExtended so that it doesn't lock the page; the caller > knows better what kind of a lock it needs. That makes it more analogous > with ReadBufferExtended too, although I think we should keep > XLogReadBuffer() unchanged for now. Much better idea, thanks. I felt a new rmgr function was overkill but couldn't think of how to do this. > See attached patch. One shortfall of this patch is that you can pass > only one argument to RestoreBkpBlocks, but there can multiple backup > blocks in one WAL record. That's OK in current usage, though. If we're doing this because of cleanup locks, then I'd say we don't currently need a cleanup lock with any WAL record that uses multiple backup blocks. So we can just document that so anybody adding such a record in the future will be careful. So all seems good. Would you want to push ResolveRedoVisibilityConflicts() down into the rmgrs as well and make reachedSafeStartPoint a global? That is only called for cleanup records. -- 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
