Re: Records, Types, and Arrays

I see.  That suggests, oddly, that pg_typeof() is changing the thing it's observing, because row(2,3) was not a record but an 'unknown typed value' before pg_typeof() was called on it.  Good to know.

CREATE CAST seems not to like working with pseudo-types.  Neither the source nor the target can be 'anyarray' or 'record'.  So that seems out.

On the other hand, the pseudo-type doc says, 'Functions coded in C (whether built-in or dynamically loaded) can be declared to accept or return any of these pseudo data types.'  I'm assuming that an 'unknown typed value" corresponds to the 'unknown' pseudo-type.  So it seems like a C function which took an anyarray as its parameter, and returned a value of type 'unknown' would bypass the need for a specifically defined cast.  (Emphasis on "seems".)