Re: Count(*) not doing a FTS??
- From: Steve Rospo <srospo@xxxxxxxxxxxxx>
- To: Oracle Discussion List <oracle-l@xxxxxxxxxxxxx>
- Date: Thu, 2 Sep 2004 17:16:43 -0700 (PDT)
Did your instructor say this with a straight face? There's no such voodoo
as a rowcount in a segment header. The two ways you can do it are a FTS
or fast full scan of a not null index. There are other more exotic ways
(materialized view) but nothing involving the segment header, that I know
of. In this case providing a counter-example is actually easier, have the
instructor provide an execution plan where that shows something other than
a FTS or index FFS.
S-
On Thu, 2 Sep 2004, rjamya wrote:
> I am sitting in a class and instructor told us that count(*) reads
> rowcount from segment header in some (or most?) cases rather than
> doign the good ol' FTS. He can't remember exact details, so this email
> ....
>
> is it true? Which version was this introduced? Someone has a
> reproducible test case?
>
> Thanks in advance
> Raj
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