I have a function in all of my databases for “grepping” for text in various types of objects in the data dictionary. Here is the code:

CREATE OR REPLACE FUNCTION schema_grep(text)
 RETURNS TABLE(schema name, object_name name, match_type text)
 LANGUAGE sql
 STABLE STRICT
AS $function$

    SELECT x.*
    FROM (
        SELECT n.nspname, c.relname, relkind_to_text(c.relkind) || ' NAME' as match_type
        FROM pg_class c, pg_namespace n WHERE c.relname ~* $1 and c.relnamespace = n.oid
      UNION ALL
        SELECT distinct n.nspname, c.relname, relkind_to_text(c.relkind) || ' ATTRIBUTE'
        FROM pg_class c, pg_attribute a, pg_namespace n WHERE a.attrelid = c.oid and c.relkind <> 'v' and a.attname ~* $1 and c.relnamespace = n.oid
      UNION ALL
        SELECT trigger_schema, format('%s.%s', event_object_table, trigger_name), 'TRIGGER ACTION'
        FROM information_schema.triggers WHERE action_statement ~* $1
      UNION ALL
        SELECT n.nspname, proname, 'FUNCTION SOURCE'
        FROM pg_proc, pg_namespace n WHERE prosrc ~* $1 and pronamespace = n.oid
      UNION ALL
        SELECT n.nspname, proname, 'FUNCTION DEFINITION'
        FROM pg_proc, pg_namespace n WHERE proname ~* $1 and pronamespace = n.oid
      UNION ALL
        SELECT schemaname, viewname, 'VIEW DEFINITION'
        FROM pg_views WHERE definition ~* $1
      UNION ALL
        SELECT schemaname, matviewname, 'MATERIALIZED VIEW DEFINITION'
        FROM pg_matviews WHERE definition ~* $1
      UNION ALL
        SELECT n.nspname, relname, 'CLASS CONSTRAINT'
        FROM pg_class c, pg_constraint cx, pg_namespace n WHERE cx.conrelid = c.oid and pg_get_constraintdef(cx.oid) ~* $1 and relnamespace = n.oid
      UNION ALL
        SELECT distinct n.nspname, c.relname, 'COMMENT'
        FROM pg_class c, pg_description d, pg_namespace n WHERE d.objoid = c.oid and d.description ~* $1 and c.relnamespace = n.oid

    ) x
$function$

I have one (and only one) database with a foreign data wrapper to another Postgres database. The relkind for this object is “f” – However, relkind_to_text returns null. Please see the following:

select distinct c.relkind, relkind_to_text(c.relkind) from pg_class as c;
+---------+-------------------+
| relkind |  relkind_to_text  |
+---------+-------------------+
| m       | MATERIALIZED VIEW |
| f       | NULL              |
| t       | TOAST TABLE       |
| S       | SEQUENCE          |
| v       | VIEW              |
| i       | INDEX             |
| c       | COMPOSITE TYPE    |
| r       | TABLE             |
+---------+-------------------+
(8 rows)

I’m currently using PostgreSQL 14. I can certainly handle it in my schema_grep function, but is this a bug? Has it been fixed in later versions of Postgresql? Are there any other types of relkinds that return null I might need to code for if I make a change this this function?