Re: [BUGS] BUG #14853: Parameter type is required even when the querydoes not need to know the type

​When PostgreSQL is done parsing a statement every externally visible element of that statement needs to have a type.  For prepared statements that means output columns and input parameters. Data types for both either need to be explicitly stated or inferred from the context of the query as parsed.

I cannot speak to the SQL standard or other databases.  I'm also not well-versed in the implementation details here - just the observed behavior.  I do suspect some possibility for improvement here but someone would have to expend considerable time and effort and the lack of comments from hackers does not bode well for that at this moment (i.e., I don't think your recommended change works but I'm not experienced enough to say for certain).  You are welcome to compile your own fork with that change incorporated and run both the PostgreSQL test suite and your application's test suite.  Favorable results there might result in provoking interest from others.

David J.