I completely agree, that was an important consideration.
I had some purely cosmetic suggestions:
1. Rename ExecComputeSlotInfo to eliminate the need for the asserts. 2. Extract return value to a bool variable for slightly better readability. 3. Taking the opportunity to use TTS_IS_VIRTUAL.
v2 of patch set attached. The first two patches are unchanged, the cosmetic
changes are part of v2-0003-Some-minor-cosmetic-changes.patch.