Re: q: read-only snapshot replication

Oracle uses snapshot logs when doing fast refreshes. When a row is changed in the master table, a trigger fires to load the modified row into the snapshot log. It doesn't take into account what the updated values are as far as I know.

Replication isn't needed for views. Remember views are nothing more than windows on to the underlying tables, they contain no data of their own. So long as you replicate the underlying tables and the view definition is there in both databases, it will appear as though the view has been replicated.

On the last question, why would you replicate the table if the data stays the same? This is one situation where I would not use replication, because you would need to quiesce the group, set up the replication for the table etc. each night. Not worth it.

HTH. Pete

dtaffe_at_my-deja.com wrote:

> When fast refresh is used, how does Oracle determined what data to
> replicate? If a value is changed by an end use from "foo" to "foo" is
> the Oracle replication machinery smart enough to know that the data is
> the same and therefore and update should not be sent over the wire? In
> other words, does Oracle simply keep a last modified date for each data
> item or is there also some sort of checksum taking place on the data
> itself?
>
> With read-only snapshot replication, is it possible to replicate a
> view? Is there an effective way to replicate a table that gets
> dropped/recreated on a nightly basis even though most of the data
> remains the same?
>
> Thanks.
>
> Sent via Deja.com http://www.deja.com/
> Before you buy.

Received on Thu Dec 23 1999 - 11:30:14 CST