On Mon, Dec 11, 2023 at 10:57:15AM +0900, Masahiko Sawada wrote: > IIUC we cannot create two same name functions with the same arguments > but a different return value type in the first place. It seems to me > to be an overkill to change such a design.
Agreed to not touch the logictics of LookupFuncName() for the sake of this thread. I have not checked the SQL specification, but I recall that there are a few assumptions from the spec embedded in the lookup logic particularly when it comes to specify a procedure name without arguments. > Another idea is to encapsulate copy_to/from_handler by a super class > like copy_handler. The handler function is called with an argument, > say copyto, and returns copy_handler encapsulating either > copy_to/from_handler depending on the argument. Yep, that's possible as well and can work as a cross-check between the argument and the NodeTag assigned to the handler structure returned by the function. At the end, the final result of the patch should IMO include: - Documentation about how one can register a custom copy_handler. - Something in src/test/modules/, minimalistic still useful that can be used as a template when one wants to implement their own handler. The documentation should mention about this module. - No need for SQL functions for all the in-core handlers: let's just return pointers to them based on the options given. It would be probably cleaner to split the patch so as the code is refactored and evaluated with the in-core handlers first, and then extended with the pluggable facilities and the function lookups. -- Michael
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