There is currently a bug found in our materialized view implementation
that happens when we delete a row, and then re-insert another row with
the same primary key.
Our insert code needs to detect updates and generate a DELETE +
INSERT. But in this case, after the initial DELETE, the fresh insert
generates another delete.
We ended up with the wrong response for aggregations (and I am pretty
sure even filter-only views would manifest the bug as well), where
groups that should still be present just disappeared because of the
extra delete.
A new test case is added that fails without the fix.
beb44e8e8c