On 28/11/2019 00:57, Tom Lane wrote:
Hence, the attached patch rearranges things so that we'll allow any case where the parser's standard coercion logic can find an assignment-level coercion, including typmod coercion if needed. In a green field I might've argued for restricting this to implicit coercions; but since some of the standard binary-compatible casts are assignment-level, that would risk breaking applications that work today. It's really safe enough though, just as assignment coercions are fine in INSERT: there's no possible confusion about which conversion is appropriate.
Makes sense. That's a nice usability improvement.
This required some adjustments of check_sql_fn_retval's API. I found that pulling out the determination of the result tupdesc and making the callers do that was advisable: in most cases, the caller has more information and can produce a more accurate tupdesc (eg by calling get_call_result_type not get_func_result_type). I also pulled out creation of the JunkFilter that functions.c wants (but none of the other callers do); having it in just one place seems simpler. A nice side-effect of these changes is that we can inline SQL functions in some cases where that wasn't possible before.
In init_sql_fcache(), one comment says that the junkfilter is responsible for injecting NULLs for dropped columns, and a later comment says that the junk filter gets "rid of any dropped columns". That seems contradictory; which is it? Or does "get rid of" mean "set to NULL"?
Other than that, looks good to me. - Heikki
