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Home -> Community -> Usenet -> c.d.o.server -> Re: UNION: SQL-tuning
Andrei Romazanov wrote:
> That is why I thought, that optimizer-strategy for table t1 from
> q1 is like one for q1 union q2.
No. A UNION is _not_ the same as SELECT. A UNION is effectively a SELECT DISTINCT. Thus your argument is flawed. CBO will not treat the SELECT on the table and the SELECT as part of a UNION the same.
-- BillyReceived on Thu Sep 12 2002 - 05:47:55 CDT
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