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Archives of the TeradataForum
Message Posted: Thu, 18 Jun 2015 @ 19:47:36 GMT
Subj: | | Re: Wrong Execution Plans |
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From: | | Gregg, William |
Hi -- U have come across one of the toughest things in our line of work. Staff use the stats diagnostic and apply all rec'd stats en masse. If
the outcome is a good one, they move on. U have to take the time to id then apply only the useful stats. When that does not happen, your situation
arises.
Another problem (fairly rare) is when a good stat goes bad. The only alert is when U receive a request to fix a query that has run without
issue "since anyone can remember ..." In my case this is the last thing I consider investigating. Finding the bad stat in a large, complex qry is
often time consuming.
The Optimizer does a great jobs these days, but it is not perfect.
Rgrds,
Bill Gregg
Teradata DBA
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