valid NaNs versus invalid NaNs?
Regarding https://arrow.apache.org/docs/memory_layout.html, how should is_valid be interpreted for primitive types that have their own notions of is_valid?
Concretely, how should folks interpret a "valid NaN" (is_valid 1 with float NaN) versus an "invalid NaN" (is valid 0 with float NaN)? In RFC-ese, MUST individual NaNs be valid? Or, MUST floats all be valid by omitting the validity bitset?
I ask because otherwise I can see a bunch of different systems interpreting this detail in many different ways. That'd be an interop nightmare. Especially since understanding why NaNs sneak into large datasets is already quite a hassle.
Anyhow, it seems worth addressing this gap at the written specification level.
(Apologies if this has been discussed previously-- I've found no searchable mailing list archives under http://mail-archives.apache.org/mod_mbox/arrow-dev/ or https://cwiki.apache.org/confluence/display/ARROW.)