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Re: Materialized View Questions

From: Arthur <amerar_at_iwc.net>
Date: 2 May 2002 06:00:25 -0700
Message-ID: <8b622eae.0205020500.162b30b4@posting.google.com>


Chris,

I am looking for a couple of specific peices of information. The first is whether or not I need a log in order to do a FAST ON COMMIT refresh. The other is how long the data will stay in the log (if I need one). Once the refresh is done, I do not need the log data anymore. And finally, what this whole thing about unique constraints on the inner table.......

Thanks,

Arthur

chrisforbis_at_yahoo.com (Chris Forbis) wrote in message news:<f2dc430d.0205011717.308938a4_at_posting.google.com>...
> The basics in a couple words are simple.
>
> If you want to make a VIEW that is just a subset of a master table the
> FAST will work, else don't bet on it.
>
> FAST requires a row to row match, otherwise full is the way to go.
>
>
> amerar_at_iwc.net (Arthur) wrote in message news:<8b622eae.0205011051.1df38d6c_at_posting.google.com>...
> > Hello,
> >
> > Continuing my research to understand these animals, I have a couple
> > more questions. I read a document on Technet about Materialized
> > Views, here is a cut of the text:
> >
> > ----------------------
> > All restrictions from "General Restrictions on Fast Refresh".
> >
> > They cannot have GROUP BY clauses or aggregates.
> >
> > If the WHERE clause of the query contains outer joins, then unique
> > constraints must exist on the join columns of the inner join table.
> >
> > Rowids of all the tables in the FROM list must appear in the SELECT
> > list of the query.
> >
> > Materialized view logs must exist with rowids for all the base tables
> > in the FROM list of the query.
> >
> > Materialized views from this category are FAST refreshable after DML
> > or Direct Load to the base tables.
> > -----------------------
> >
> > I'm unclear about the whole concept surrounding the necessary rowid
> > and having a unique constraint on the inner joined table. I want to
> > do a FAST ON COMMIT refresh of this view, since it takes early 3 hours
> > to do a complete refresh......
> >
> > Also, once refreshed, is the data purged from the materialized view
> > log? Once applied, I do not need the data in the log anymore. We are
> > running 8.1.5.
> >
> > Thanks,
> >
> > If you can, also cc a copy to my email.
> >
> > Arthur
> > amerar_at_iwc.net
Received on Thu May 02 2002 - 08:00:25 CDT

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