Attached is v14 which adds back in tests for the BUFFER_USAGE_LIMIT
option. I haven't included a test for VACUUM (BUFFER_USAGE_LIMIT x,
PARALLEL x) for the reason I mentioned upthread -- even if we force it
to actually do the parallel vacuuming, we are adding exercising the code
where parallel vacuum workers make their own buffer access strategy
rings but not really adding a test that will fail usefully. If something
is wrong with the configurability of the buffer access strategy object,
I don't see how it will break differently in parallel vacuum workers vs
regular vacuum.
- Melanie