Calling `enableSendingOldValues` on many nodes, e.g. `KTableFilter`, is unnecessarily calling `enableSendingOldValues` on the parent, even when the processor itself is materialized. This can force the parent table to be materialized unnecessarily.
If `downStreamOps` result in a call to `enableSendingOldValues` on the table returned by the `filter` call, i.e. `t2`, then it will result in `t1` being materialized unnecessarily.
A good test that highlights this would be to add this to `KTableFilterTest`:
Though this problem is not restricted to the filter call. Other processor suppliers suffer from the same issue.
In addition, once https://github.com/apache/kafka/pull/9156 is merged, if you call enableSendingOldValues without forcing materialization on a table that is itself materialized, but who's upstream is not. In such a situation, the table will not enable sending old values, but should.