AW: Storage Manager (was postgres 7.2 features.)

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От Zeugswetter Andreas SB
Тема AW: Storage Manager (was postgres 7.2 features.)
Дата
Msg-id 11C1E6749A55D411A9670001FA687963367FF2@sdexcsrv1.f000.d0188.sd.spardat.at
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Ответы Re: AW: Storage Manager (was postgres 7.2 features.)  (JanWieck@t-online.de (Jan Wieck))
Список pgsql-hackers
> > * It's always faster than WAL in the presence of stable main memory.
> > (Whether the stable caches in modern disk drives is an 
> approximation I
> > don't know).
> 
>     For writing, yes. But for high updated tables, the scans will
>     soon slow down due to the junk contention.

Can you elaborate please ? If we centralized writes, then the
non-overwrite smgr would be very efficient since it only writes to the end 
of a table (e.g. one page write for pagesize/rowsize rows). 

> 
> > * It's more scalable and has less logging contention. This allows
> > greater scalablility in the presence of multiple processors.
> >
> > * Instantaneous crash recovery.
> 
>     Because  this never worked reliable, Vadim is working on WAL

crash recovery is bullet proof. the WAL is only needed for rollforward 
after restore with our non overwrite smgr. 
I do agree that we need a txlog. 

Andreas


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