Re: Dead Space Map
От | Hannu Krosing |
---|---|
Тема | Re: Dead Space Map |
Дата | |
Msg-id | 1141113144.3775.13.camel@localhost.localdomain обсуждение исходный текст |
Ответ на | Re: Dead Space Map (Tom Lane <tgl@sss.pgh.pa.us>) |
Ответы |
Re: Dead Space Map
Re: Dead Space Map |
Список | pgsql-hackers |
Ühel kenal päeval, E, 2006-02-27 kell 13:17, kirjutas Tom Lane: > Heikki Linnakangas <hlinnaka@iki.fi> writes: > > Vacuum will need to be modified to use index lookups to find index tuples > > corresponding the dead heap tuples. Otherwise you have to scan through > > all the indexes anyway. > > This strikes me as a fairly bad idea, because it makes VACUUM dependent > on correct functioning of user-written code --- consider a functional > index involving a user-written function that was claimed to be immutable > and is not. There are concurrency-safety issues too, I think, having to > do with the way that btree ensures we don't delete any index tuple that > some scan is stopped on. > > > * vacuuming pages one by one as they're written by bgwriter > > That's not happening. VACUUM has to be a transaction WHY does vacuum need to be a tranasction ? I thought it was a programmer workload optimisation (aka. lazyness :) ) to require ordinary lazy vacuum to be in transaction. There is no fundamental reason, why vacuum needs to run in a transaction itselt. ----------------- Hannu
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