Re: Logical Standby..

  • From: "Ravi Gaur" <ravigaur1@xxxxxxxxx>
  • To: Smith.Steven@xxxxxxx
  • Date: Thu, 19 Jul 2007 18:36:17 -0500

We use Oracle Streams for replicating a small set of tables (relatively) and
the way I understand it is if you want to include most of everything inside
the database (ie exclude a small %age of tables), try logical standby versus
if you want to exclude everything (ie include only a small %age of tables),
think of Oracle streams. Under the covers, they both use the logminer to
capture changes, propagate and apply it to the destination site. However,
streams has a bit of administrative overhead (in my opinion) compared to a
logical standby.

If you decide on going w/ logical standby, you'll need to setup filters
(skip filters I believe) to exclude the tables you don't want (and then
perhaps simply drop them from the destination) otherwise you might see
numerous errors (object not found) from SQL apply. Someone with a greater
experience w/ logical standby might want to chime in and correct me if I
misspoke.

- Ravi Gaur
Lead Systems DBA
Univ of IL


On 7/19/07, Smith, Steven K - MSHA <Smith.Steven@xxxxxxx> wrote:

In a logical standby database scenario, can you pick and choose the
objects that you want to replicate to the standby instance?

We have auditing tables associated to every table in the OLTP
environment - populated through triggers for updates and deletes.  We
want to replicate some of the OLTP environment tables to a reporting
environment with different indexing options.  We do not have a need to
replicate the audit tables with the primary tables.

Does Data Guard using logical standby allow a 'pick and choose' option
for objects that are replicated?

From reading the manuals, it appears that the logical standby is created
as a duplicate of the primary database and then the redo logs are mined
to keep the standby in sync with the primary.  Once the standby is in
place, is it possible to drop objects in the standby and continue
logically keeping the remaining objects refreshing?  I have experience
with physical standby, but not logical standby.

Thanks for any help.

Steve
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