Re: MView data problem

Manoj,

This is a problem with the full refresh of an MV. The refresh initially truncates the table and then issues a full refresh. To resolve this problem, here are some steps:

Create the MV as a table first and then build the MV with "ON PREBUILT TABLE" clause.
When created this way the drop snapshot (or MV) command does __not__ drop the segment; the table remains.
Before doing the full refresh, drop the snapshot Copy the underlying table to a new name
Then recreate a snapshot wth ON PREBUILT TABLE clause. Do a full refresh.
While the full refresh is going on, you can refer to the copied table for the previous data.

I did a presentation at IOUG Live this year which is along similar lines - "Painless Alter of Master Table in Replication", which you can find on my website, www.proligence.com.

Hope this helps.

Arup

• Original Message ----- To: "Multiple recipients of list ORACLE-L" <ORACLE-L_at_fatcity.com> Sent: Tuesday, June 03, 2003 9:19 AM

> Hi All,
>
> I have a mview(Materialized View) that i refresh
> ONDEMAND. This Mview takes 15 minutes in refresh as it
> involves a complex query and lots of data in master
> table. But as soon as the refresh starts old data gets
> deleted from the mview and there is no data in mview
> untill the refresh is complete. As i m querying the
> mview in my scripts i get no data if some request is
> sent during that refresh interval. Can we keep this
> old data untill new data gets populated? Or is there
> anyway that we can reduce this time period for which
> there is no data in mview?
>
> Thanks in advance
>
> Manoj Ahuja
>
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-- 
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-- 
Author: Arup Nanda
  INET: orarup_at_hotmail.com

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