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Message Posted: Thu, 02 Mar 2006 @ 14:43:18 GMT


     
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Subj:   Table and join sequences..
 
From:   Anomy Anom

<-- Anonymously Posted: Thursday, March 02, 2006 06:09 -->

Dear all,

I ve come into TD with some Oracle experience. In writing Oracle queries, we follow a general rule to select the least bulkiest table last in the SELECT statement. What is mean is If tabA and tabB are two tables having 1 and 10000 rows respectively, I would write a query like SELECT count(*) from tabB, tabA than SELECT count(*) from tabA, tabB coz oracle works from 'right to left' . Same for the case of joins where we are advised to put the most restrictive join at the end.

Any such rules necessary for teradata? If there are a series of equi-joins spawning a few intermediate spool files in the process, how do I arrange the join sequence such that the query would consume the least amount of resources ?


Many regards



     
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