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Message Posted: Tue, 22 Aug 2006 @ 14:35:03 GMT

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If Teradata decides to not use the JI, it is because it believes it to use more resources than doing the join. You have not given us one piece of info on the JI - result of a real join, a single table JI, an aggregate JI or a sparse JI. We don't know anything about the underlying tables regarding their PI definitions nor structure. So, I will guess that you are using the conventional JI resulting from a join.

1. Did you select one or more columns from the underlying table(s) that were not selected in the JI?

2. Did you collect statistics on the JI?

3. Is the JI in the same database as the tables - things like access privileges?

If I applied any real thought to this I might even come up with other questions for you, if I knew who you are.

As if an EXPLAIN is not already verbose, you want more? Should it stop at only one reason or should it have a parameter so you can specify the number of reasons to return for NOT doing something?

Hope this gives you some ideas in your quest.

Michael Larkins
Certified Teradata Master
Certified Teradata SQL Instructor

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