I'd like to propose support for IN and OUT parameters in 'DO' blocks.
Currently, anonymous code blocks (DO statements) can not receive or return parameters.
I suggest:
1) Add a new clause to DO statement for specifying names, types, directions and values of parameters:
DO <code> [LANGUAGE <lang>] [USING (<arguments>)]
where <arguments> has the same syntax as in 'CREATE FUNCTION <name> (<arguments>)'.
Example:
do $$ begin z := x || y; end; $$ language plpgsql using ( x text = '1', in out y int4 = 123, out z text );
2) Values for IN and IN OUT parameters are specified using syntax for default values of function arguments.
3) If DO statement has at least one of OUT or IN OUT parameters then it returns one tuple containing values of OUT and IN OUT parameters.
Do you think that this feature would be useful? I have a proof-of-concept patch in progress that I intend to publish soon.
shortly
+1 parametrization of DO statement
-1 OUT parameters for DO - when you need OUTPUT, then use a function. A rules used for output from something are messy now, and I strongly against to do this area more complex. Instead we can define temporary functions or we can define real server side session variables.