Re: How smart are Snapshots ?

Heber Ferraz-Leite wrote:
>
> Hi,
>
> I was just wondering how smart Oracle behaves in the create snapshot
> statement.
>
 

> When I say "update snapshot", will Oracle basically copy the whole
> table again, or will it be smart enough to know where the table has
> been changed since the last update snapshot and only copy whatever has
> been changed ?
>

You have the choice of either updating a snapshot fast or complete.

A fast refresh only adds the records that have been added/updated since the last refresh.
To do this you will need to create snapshot logs on the 'source' server, and the
snapshot with a 'fast refresh' on the 'destination' server. You can perdiodically update
the snapshots with a dbms job, or you can refresh them with an 'alter snapshot x refresh fast'
statement from sqlplus/svrmgr...

A complete refresh truncates the table and refreshes it from scratch.

So, in short, you should be able to do as you wish, by using fast refresh on the snapshots...

Cheers

Adam (who has just finished doing this at his own site) Received on Mon Dec 22 1997 - 00:00:00 CST