Re: DBA_OBJECTS using Distinct Vs Group By
- From: Deepak Sharma <sharmakdeep_oracle@xxxxxxxxx>
- To: mcdonald.connor@xxxxxxxxx, oracle-l@xxxxxxxxxxxxx
- Date: Thu, 22 Jun 2006 10:51:24 -0700 (PDT)
That doesn't seem to be it. I tried disabling "HASH
GROUP BY" and the plan now shows "SORT GROUP BY", but
still the "GROUP BY" timing is same with or w/o this
setting.
--> "_gby_hash_aggregation_enabled"=false
The one difference I see in the plan for "DISTINCT" is
it does a Hash Join between and "I_OBJAUTH1" and
"X$KZSRO", whereas the "GROUP BY" plan shows a Nested
Loop between the same two. In fact the GROUP BY
query's cost is higher (but of course that doesn't
govern the timing necessarily).
Thanks,
Deepak Sharma
--- Connor McDonald <mcdonald.connor@xxxxxxxxx> wrote:
> On 6/22/06, Deepak Sharma
> <sharmakdeep_oracle@xxxxxxxxx> wrote:
> >
> > Any ideas why "GROUP BY" query is faster that
> > "DISTINCT" in this query?
> >
> > SELECT OWNER FROM DBA_OBJECTS GROUP BY OWNER;
> >
> >
> >
> Without doing any real analysis on it, I'm guessing
> that the group by is
> getting benefit from the new "HASH GROUP BY" in 10g.
>
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