Re: Load and Query question
- From: "jaromir nemec" <jaromir@xxxxxxxxxxxx>
- To: <gogala@xxxxxxxxxxxxx>, "'Oracle Discussion List'" <oracle-l@xxxxxxxxxxxxx>
- Date: Sat, 29 Apr 2006 22:56:04 +0200
Mladen,
In data warehouse situation, you don't have to prevent data from entering,
data is
already checked and trusted, you are extracting data from your OLTP
database, ..
I'd love to operate a DW above your OLTP. In my experience I sow a lot of
systems where the data is only trusted.
You must index your DW properly. Indexing schemes are widely described
in various books.
paradoxically from the point of view of loading data in DW with full refresh
(as discussed in this thread) the best indexing schema is the empty one as
* the indices needn't be refreshed on load (with or without APPEND)
* don't get invalid on partition exchange (this is getting better in newer
releases)
* don't need to be reanalysed
* optimizer is not tempted to start NL with large loops
etc.
Of course those that are performing query of the data in DW see this a
little different:)
Regards,
Jaromir
----- Original Message -----
From: "Mladen Gogala" <gogala@xxxxxxxxxxxxx>
To: <shreeni@xxxxxxxxxxxxx>
Cc: "'Oracle Discussion List'" <oracle-l@xxxxxxxxxxxxx>
Sent: Thursday, April 27, 2006 5:44 PM
Subject: Re: Load and Query question
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