您的查询不合理，在复合外键的情况下，它返回了太多（重复）的行。我建议在这些情况下使用string_agg()返回列名列表。将pg_class连接到pg_constraint以获取表的所有者名称：

select
    cb.relname as base_table,
    cb.relowner::regrole as base_owner,
    (select string_agg(attname, ',') 
        from pg_attribute 
        where attrelid = confrelid and attnum = any(confkey)
    ) as base_columns,
    cr.relname as referencing_table,
    cr.relowner::regrole as reftable_owner,
    (select string_agg(attname, ',') 
        from pg_attribute 
        where attrelid = conrelid and attnum = any(conkey)
    ) as ref_columns
from pg_constraint c 
join pg_class cb on cb.oid = c.confrelid
join pg_class cr on cr.oid = c.conrelid
where c.confrelid = 'public.master'::regclass
-- sample owner condition
and cb.relowner = 'postgres'::regrole

在db<>fiddle.中测试
更新。系统编录pg_class的列relnamespace包含有关表模式的信息：

select
    cb.relname as base_table,
    cb.relnamespace::regnamespace as base_schema,
    (select string_agg(attname, ',') 
        from pg_attribute 
        where attrelid = confrelid and attnum = any(confkey)
    ) as base_columns,
    cr.relname as referencing_table,
    cr.relnamespace::regnamespace as reftable_schema,
    (select string_agg(attname, ',') 
        from pg_attribute 
        where attrelid = conrelid and attnum = any(conkey)
    ) as ref_columns
from pg_constraint c 
join pg_class cb on cb.oid = c.confrelid
join pg_class cr on cr.oid = c.conrelid
-- sample schema condition
where cb.relnamespace = 'public'::regnamespace;

在db<>fiddle.中测试