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Re: Logical StandBy question

From: Walt Weaver <>
Date: Wed, 12 Nov 2003 12:34:26 -0800
Message-ID: <>

Thanks for the info on logical standbys everyone.

The opinions on it seem rather unanimous. :>)


On Wed, 2003-11-12 at 12:14, Stephane Faroult wrote:
> Walt Weaver wrote:
> >
> > Stephane,
> >
> > What sort of problems can one expect from logical standby?
> >
> > I'm toying with the idea of using it as a replication database -- no
> > additional schema objects will be created, but users will have read-only
> > access to it. It's one of the options I'm looking at.
> >
> > Seems to me like there was a thread on this a few months ago, but I'm
> > not sure...
> >
> > --Walt
> >
> Walt,
> This is basically my feelings after the tests :
> o Properly monitoring is rather difficult. You must check at both ends
> to have more than a vague feeling that things could have gone awry. This
> is just one aspect of a general user-friendliness which first shows up
> in a 26 step installation procedure.
> o The automated check for incompatibilities (there is normally a view
> to tell you what will not work) is fairly deficient. I have (by mistake)
> tested on a schema with lots of (unsupported) LONGs, do you think I got
> any warning?
> o Although a surprisingly high number of DDL commands are successfully
> replicated (including CREATE USER, etc), others are understandably not
> replicated (when you extend a tablespace - well the directory lay-out
> may be different, so it makes sense. The workaround is to have
> AUTOEXTEND ON, which I am usually reluctant to have), something as
> mundane as RENAME is not - with all the ensuing consequences you may
> imagine.
> o I have found no way to ensure that the time gap between the two
> databases stayed below some predefined threshold. Not sure that issuing
> regular ALTER SYSTEM SWITCH LOGFILE on the master is enough.
> I wanted to test the performance impact of logical standby by running an
> import, first without it, then with it, and also to measure how fast the
> copy was catching up, but I've given up my tests after a few ORA-600
> errors.
> The concept is great, and I am sure to have another look at it ...
> later.
> --
> Regards,
> Stephane Faroult
> Oriole Software
> --
> Please see the official ORACLE-L FAQ:

Please see the official ORACLE-L FAQ:
Author: Walt Weaver

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Received on Wed Nov 12 2003 - 14:34:26 CST

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