Github user hbdeshmukh commented on the issue:
https://github.com/apache/incubator-quickstep/pull/181
One case which is currently not considered is the following:
Imagine a join between two relations. The probe side is a result of a
selection on a base relation. The probe's base relation is hash partitioned on
attribute ``a``. There are two cases:
1. In the projection, the attribute ``a`` is left out, i.e. we don't
project it.
2. We project the attribute ``a``.
If you look at the code of ``convertSelection``, the output of the
selection has no partitioning scheme. In case two, we can carry forward the
partitioning scheme from the base table to the output of the selection. That
way, you can avoid the repartitioning step for the probe side.
To summarize, you need to add a check in ``convertSelection`` that can
identify case 1 and case 2 mentioned earlier.
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