diff --git a/quack--0.0.1.sql b/quack--0.0.1.sql
index e61f1782..0f10c42c 100644
--- a/quack--0.0.1.sql
+++ b/quack--0.0.1.sql
@@ -4,6 +4,30 @@ CREATE OR REPLACE FUNCTION read_parquet(path text)
 RETURNS SETOF record LANGUAGE 'plpgsql' AS
 $func$
 BEGIN
-  RETURN QUERY EXECUTE 'SELECT 1';
+   RAISE EXCEPTION 'Function `read_parquet(TEXT)` only works with Duckdb execution.';
+END;
+$func$;
+
+CREATE OR REPLACE FUNCTION read_parquet(path text[])
+RETURNS SETOF record LANGUAGE 'plpgsql' AS
+$func$
+BEGIN
+   RAISE EXCEPTION 'Function `read_parquet(TEXT[])` only works with Duckdb execution.';
+END;
+$func$;
+
+CREATE OR REPLACE FUNCTION read_csv(path text)
+RETURNS SETOF record LANGUAGE 'plpgsql' AS
+$func$
+BEGIN
+   RAISE EXCEPTION 'Function `read_csv(TEXT)` only works with Duckdb execution.';
+END;
+$func$;
+
+CREATE OR REPLACE FUNCTION read_csv(path text[])
+RETURNS SETOF record LANGUAGE 'plpgsql' AS
+$func$
+BEGIN
+   RAISE EXCEPTION 'Function `read_csv(TEXT[])` only works with Duckdb execution.';
 END;
 $func$;