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Message Posted: Fri, 20 Feb 2004 @ 18:00:13 GMT

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Subj:   Re: Simple question about a left outer join...
From:   Dieter Noeth

Victor Sokovin wrote:

  Thank you for the explain. It looks like it does not take advantage of the "is null" condition on the large table and builds the product join on the full tables, which is something you should avoid by all means.  

Just tell the truth, the plan is totally stupid ;-) It's duplicating all rows and then doing a useless 'product join, with a join condition of ("(1=0)")'

  There are a few counts in the explain which I don't understand. For example, how 54,587,480 rows from Step 4 ("estimated with high confidence") relate to the fresh table row count you mentioned (5,461,246).  

He's running a 10 AMP system (Spool 2 duplicated on all AMPs)

  It might be worth reporting this case to your NCR rep, especially if you are using one of the recent releases.  

(all_amps) in Explain -> He's at least on V2R5

  In the meantime you will of course need another solution. Perhaps you could use alternatives suggested by Mirjam and Henry or tell us what your purpose is so that people can generate more ideas, if necessary.  



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