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Tera-Tom on Teradata Physical Implementation V12-V13 by Tera-Tom Coffing

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Chapter 11 – Join Indexes

“The Strongest Memory is Weaker than the Palest Ink.”

– Anonymous

 

The following page shows a pictorial of a Join Index. You can see the SQL used to CREATE the Join Index. You can also see both the base tables which are the Employee_Table and the Department_Table. The Join Index joins the two tables together and keeps the result set inside PERM Space. Users don’t ever query the Join Index, but only query the base tables. If a user does join these two tables together the Parsing Engine will be the one to decide if it is faster to build the answer set from the Join Index instead of actually performing the Join on the Base Tables. In a sense the Join Index is the result of joining the two tables together so the Parsing ...

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