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Re: Standby on different platforms

From: Howard J. Rogers <howardjr2000_at_yahoo.com.au>
Date: Wed, 11 Dec 2002 19:14:38 +1100
Message-ID: <1lCJ9.995$jM5.2873@newsfeeds.bigpond.com>

"Paul Brewer" <paul_at_paul.brewers.org.uk> wrote in message news:3df6f0fa_2_at_mk-nntp-1.news.uk.worldonline.com...
> "Richard Foote" <richard.foote_at_bigpond.com> wrote in message
> news:8bkJ9.454$jM5.1352_at_newsfeeds.bigpond.com...
> > Hi Steven,
> >
> > The answer is no.
> >
> > BUT ORACLE, IF YOU'RE LISTENING, THIS WOULD BE A REALLY HANDY FEATURE !!
> >
> > Maybe one day with the Logical SB.
> >
> Richard,
>
> What's a logical SB?

With traditional standby, we ship redo change vectors ("Change this column for rowid x.x.x.x and set value to Y") -which means that every row must be in exactly the same spot on both the primary and the standby (because file number, for example, is part of the rowid -so if it's file 6 on the primary, it's got to be file 6 on the standby).

New in 9i is the logical database, where we convert the redo change vector into a simple SQL statement ("update emp set sal=8000 where ename='BOB'"). Meaning that the EMP table can be in file 6 on ythe primary, but file 67 on the standby for all we care: SQL is SQL and works, wherever the EMP table is.

Now don't ask me why the logical standby doesn't work across different platforms, because in my book, SQL issued on NT should be identical to the SQL issued on Unix.... but it doesn't. But I suspect there's no fundamental reason that it can't be *made* so to work in future releases, so I'm confidently expecting Richard's wish to come true in the future. Sometime.

But what do I know??

Regards
HJR
>I'd have thought we'd need something like a logical
> redo log to transport and apply.
> I must be missing something here.
> Serious question, btw, even if stupid.
>
> Regards,
> Paul
>
>
>
Received on Wed Dec 11 2002 - 02:14:38 CST

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