Support schema (namespace) of functions

[xxchan]

Since we are developing UDFs, this should be considered.

e.g., in PG

xxchan@/tmp:postgres> select * from _pg_expandarray(Array[1,2,3]);
function _pg_expandarray(integer[]) does not exist
LINE 1: select * from _pg_expandarray(Array[1,2,3])
                      ^
HINT:  No function matches the given name and argument types. You might need to add explicit type casts.
Time: 0.024s
xxchan@/tmp:postgres> set search_path = information_schema;
SET
Time: 0.001s
xxchan@/tmp:postgres> select * from _pg_expandarray(Array[1,2,3]);
+---+---+
| x | n |
|---+---|
| 1 | 1 |
| 2 | 2 |
| 3 | 3 |
+---+---+

[github-actions]

This issue has been open for 60 days with no activity. Could you please update the status? Feel free to continue discussion or close as not planned.