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Message Posted: Fri, 26 Mar 2004 @ 18:29:08 GMT


     
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Subj:   Re: Aggregate Join Index & Fallback
 
From:   Ballinger, Carrie

I haven't tested this condition either, but I checked in the Database Design manual V2R5.1 (page 12-6) and the text does suggest that a join index with fallback WOULD be used if an AMP is down.

"If you do not define fallback for a join index and an AMP is down, then the following additional criteria become critical:

1. The join index cannot be used by the Optimizer to solve any queries that it covers

2. The base tables on which the join index is defined cannot be updated."


If the join index is being used for partial covering (which results in joining back to the base table rows) the optimizer would not be able to use the JI if the base table was not also fallback protected, but it sounds like a JI that covers the query completely would be used.


Thanks, --Carrie



     
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