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Archives of the TeradataForum
Message Posted: Thu, 02 May 2008 @ 00:04:02 GMT
| Subj: | | Re: Retrieving the Second Highest Amount |
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| From: | | Dieter Noeth |
Michael Larkins wrote:
| | The real question is whether or not the optimizer is acting correctly in its choice regarding the timing of applying the WHERE
conditions. | |
Of course the optimizer is right, it can only push a condition into a view/derived table, if it's not changing the result set.
Just imagine the condition pushed into a view doing an aggregation,
removing rows before the SUM.
| | Otherwise, why does the optimizer not always read all rows into spool and then select from spool based on the select from the
view. | |
If you use a (PARTITION BY customer, cust_date), then it will push a condition on cust_date.
There's no efficient solution (beside Victor's proposition, which will result in a huge cross join/spool) to Megan's problem including all 4
requirements.
Dieter
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