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Message Posted: Mon, 03 Apr 2007 @ 01:34:39 GMT
| Subj: | | Re: Order of inner joins alter plan |
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| From: | | Walter, Todd |
The referred to change to the optimizer was included in V2R5.1.
It is not the expected behaviour to have order change the plan. It can happen if different options look like equal cost to the optimizer, but
of course that would not be predictable or controllable.
Of course if there are any OJs in the mix, then the order does matter and the results can be affected by changing the order.
P.S. I keep seeing people referring to ANSI syntax versus Teradata syntax. The syntax of specifying the list of tables, comma separated, in the
FROM clause and all the join conditions in the WHERE clause is ANSI standard equally as much as the INNER join syntax. INNER was added to the
standard concurrently with the OJ variations because otherwise it would be difficult to mix a combination of outer and inner. But the prior syntax
was not removed or deprecated in any way and is perfectly acceptable ANSI syntax.
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