Re: Hot Standby (commit fest version - v5)
От | Simon Riggs |
---|---|
Тема | Re: Hot Standby (commit fest version - v5) |
Дата | |
Msg-id | 1227197641.7015.56.camel@ebony.2ndQuadrant обсуждение исходный текст |
Ответ на | Re: Hot Standby (commit fest version - v5) (Tom Lane <tgl@sss.pgh.pa.us>) |
Список | pgsql-hackers |
On Thu, 2008-11-20 at 10:33 -0500, Tom Lane wrote: > "Pavan Deolasee" <pavan.deolasee@gmail.com> writes: > > I wonder if we should refactor lazy_scan_heap() so that *all* the real work > > of collecting information about dead tuples happens only in > > heap_page_prune(). Frankly, there is only a rare chance that a tuple may > > become DEAD after the pruning happened on the page. We can ignore such > > tuples; they will be vacuumed/pruned in the next cycle. > > > This would save us a second check of HeapTupleSatisfiesVacuum on the tuples > > which are just now checked in heap_page_prune(). In addition, the following > > additional WAL records are then not necessary because heap_page_prune() must > > have already logged the latestRemovedXid. > > I don't think you can do that. Couldn't someone else have run > heap_page_prune between vacuum's first and second visit to the page? I just looked at that in more detail and decided it was more difficult than it first appeared. So I've left it for now. -- Simon Riggs www.2ndQuadrant.comPostgreSQL Training, Services and Support
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