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RE: automatic refresh of delta data for materialized views

From: Ferenc Mantfeld <fmantfeld_at_siebel.com>
Date: Thu, 06 Jun 2002 00:38:20 -0800
Message-ID: <F001.00475EF3.20020606003820@fatcity.com>


<<Ferenc,

   This has just crossed my mind and perhaps that after I think harder I'll find it a foolish idea, but would it be possible to have snapshot logs (or their home-made equivalents) on all the tables in the view and building a 'delta view' on top of those logs ?>>

FM : Stephane, thanks for replying, as I am still not coming up with any good ideas myself on this. The whole snapshot idea has not crossed my mind until you mentioned it, but even with the snapshot logs, I would still need to calculate the summaries and aggregates on the entire set of tables in the join, which is essentially what I wanted the materialized view for in the first place. for small to normal size DW, this is not too much of a problem, but for the very large (1 TB size) DW, where they would want to load incrementally almost daily, this would pose an extremely long running process, and even if the various MV's are refreshed in parallel, if loaded daily, I doubt there would be enough time between the ETL loads and when the DSS users come in to work, that the processes would get finished. Of course without summarized tables or MV, the whole idea of available aggregations is preposterous to begin with.

Thanks for thinking of this. I will probably try it to see what I can conjure up.

Ferenc

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Author: Ferenc Mantfeld
  INET: fmantfeld_at_siebel.com

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