help me win this "group by" argument
- From: <babette.turnerunderwood@xxxxxxxxxxxxxxx>
- To: <oracle-l@xxxxxxxxxxxxx>
- Date: Tue, 23 Mar 2004 15:32:00 -0500
Two co-workers and I were discussing the mechanism that
Oracle uses to do group by and whether sorts were required or not.
My understanding is the intermediate result set is sorted and
whether the source data has be sorted or not depends on the
type of group by function being applied. If it is a SUM or a COUNT,
Oracle just increments the values. But if it is an average then
Oracle sorts the original data into the group by values and then
does the calculations.
Co-worker one says that Oracle always just increments the counts
and for a AVG it will just be incrementing the SUM and COUNT
and then use those for AVG.
Co-worker two says Oracle always sorts the data by the group by
value and then applies the function..
So who's right ?
Thanks
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