Indices in Postgres do contain NULL values. My guess is that it's possible to make IS DISTINCT FROM an indexable operator, but it wouldn't be straightforward gi

Indices in Postgres do contain NULL values. My guess is that it's possible to make IS DISTINCT FROM an indexable operator, but it wouldn't be straightforward given that NULLs are a bit of a special case for indexing comparisons in the sense that they totally ignore data types. IS DISTINCT FROM would probably have to redefine a bunch of existing opclasses to account for the possibility of NULL.