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Message Posted: Tue, 13 Jun 2000 @ 20:37:32 GMT


     
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Subj:   Re: Hot Amp
 
From:   John Hall

Per John Street's suggestion, start off by re-collecting the statistics. It is generally a good practice, if not a rule, that you should re-collect statistics when upgrading from one release to another.

The statistics for any given column is held in DBC.TVFIELDS, column FIELDSTATISTICS. The statistics for an index is held in DBC.INDEXES, column INDEXSTATISTICS. These two columns are both VARBYTE fields. Although the binary layout of these two columns has been pretty consistent from release to release, I'm under the impression that NCR is free to change them whenever they like (the physical layout has never been documented for the customer). The only way to be sure that you aren't going to have a statistics problem when you change releases, is to re-collect them as soon as your upgrade has been completed.

If new statistics don't fix your problem, then it sounds like you might need to re-index your table - although I would hate to say it is your specific problem (I think that you would need to send your table, the problem query and its EXPLAIN to be certain).

Just a quick comment: don't confuse the logical model from which you designed your database with the physical model from which you actually designed your tables. You should be able to accommodate your existing model by re-indexing the primary index and adding one or more secondary indexes.

There was a recent thread that you might look at: you might benefit by dropping DATE from your UPI. The thread was started by Beth Withers (look at the last three or four sentences of Beth's note):

www.teradataforum.com/teradata/20000525_180305.htm

Use the 'Next in Topic' button to follow the thread (the fourth button from the left).



     
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