Re: Hot Standby on git
От | Simon Riggs |
---|---|
Тема | Re: Hot Standby on git |
Дата | |
Msg-id | 1254768589.4691.249.camel@ebony.2ndQuadrant обсуждение исходный текст |
Ответ на | Re: Hot Standby on git (Tom Lane <tgl@sss.pgh.pa.us>) |
Список | pgsql-hackers |
On Mon, 2009-10-05 at 10:19 -0400, Tom Lane wrote: > Simon Riggs <simon@2ndQuadrant.com> writes: > > I don't see how that helps at all. The objective of lock counters was to > > know if we can skip acquiring an LWlock on all lock partitions. This > > change keeps the lock counters yet acquires the locks we were trying to > > avoid. This change needs some justification since it is not a bug fix. > > [ scratches head ... ] Why is hot standby messing with this sort of > thing at all? It sounds like a performance optimization that should > be considered separately, and *later*. Possibly. We have 3 suggested approaches: * Avoid taking LockPartition locks while we get info for Hot Standby during normal running, by means of a ref counting scheme (Simon) * Take the locks and implement a ref counting scheme (Heikki) * Take the locks, worry later (Tom) The middle ground seems pointless to me. I'm happy to go with simple lock-everything-for-now but it's pretty clear its going to be a annoying performance hit. If we do that we should put in a parameter to turn on/off so that those who will never use Hot Standby can avoid this completely. I'll wait for Heikki's thoughts before implementing anything. -- Simon Riggs www.2ndQuadrant.com
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