I personally don't see any benefit in this change. The focus shouldn't be on fixing things that aren't broken. Perhaps, there is more value in using bitmap data type to keep track of NULL values, which is typical storage vs performance debate, and IMHO, it's better to err on using slightly more storage for much better performance. IIRC, the bitmap idea has previously discussed been rejected too.
When I review the [1], I find that the tuple's nulls array use char type. However there are many places use boolean array to repsent the nulls array, so I think we can replace the char type nulls array to boolean type. This change will break the SPI_xxx API, I'm not sure whether this chagnges cause other problems or not. Any thought?
