partial automatic index is allowed in order to capture more cases where it
is legal to use a partial automatic index.
FossilOrigin-Name: 664b461bb5063d98047fc2e51a3827235cd9f55ca2e23cb66e719eac53fb5437
if the constraint that qualifies the partial index is part of the ON clause of
a LEFT JOIN.
FossilOrigin-Name: 1a1516e4da26dcee35e6fbb6604ce252faf3d116