Yes - there is an optimization process that will perform a cartesian join
IF one of the row sources will return a single row. I don't recall when it
was introduced (11gR2?). Seeing 'CARTESIAN' in the query plan used to be a
big ol' red flag...now it is an indication that you should take a closer
look at the row sources in the join.
On Tue, Apr 2, 2019 at 2:26 PM Ram Raman <veeeraman@xxxxxxxxx> wrote:
I am not a big expert on joins, but I think Oracle chooses Cartesian when
it thinks one of the row sources is going to return only one row.
On Sat, Mar 30, 2019 at 3:08 PM Orlando L <oralrnr@xxxxxxxxx> wrote:
List
When is it OK to do Cartesian joins?
1) It looks like during the star transformation while joining 2 or more
small result sets from dimension tables?
2) In an ordinary join, when one of the row sources is estimated to be 1
row with the other row source be several thousand? In this case, the
Cartesian will be just 1*no of rows in the other table.
Any explanation is helpful. thanks
Orlando.
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