CDB_ColumnNames should honor regclass

[rochoa]

CDB_ColumnNames current implementation returns columns for any table matching the name.

When having multiple tables with same name but in a different schema it will report the column name from all the tables.

regclass should be considered when providing qualified table names.

[iriberri]

SB/6362235

[javisantana]

why not using the oid so we don't need to add a filter by schema?

@iriberri CDB_ColumnNames is not public api, ping the user about this.

[rochoa]

You are right, actually the signature is CDB_ColumnNames(REGCLASS) so it should be a bugfix more than a new feature as it's already possible to do:

select CDB_ColumnNames('foo.table_name');
select CDB_ColumnNames('bar.table_name');