diff --git a/scripts-available/CDB_ColumnNames.sql b/scripts-available/CDB_ColumnNames.sql
index 22842bd..c35ba99 100644
--- a/scripts-available/CDB_ColumnNames.sql
+++ b/scripts-available/CDB_ColumnNames.sql
@@ -5,9 +5,9 @@ AS $$
   SELECT
     a.attname::information_schema.sql_identifier column_name
     FROM pg_class c
-         LEFT JOIN pg_catalog.pg_attribute a ON a.attrelid = c.oid
+         LEFT JOIN pg_attribute a ON a.attrelid = c.oid
     WHERE c.oid = $1::oid
-    AND a.attstattarget = -1
+    AND a.attstattarget < 0 -- exclude system columns
    ORDER BY a.attnum;
 $$ LANGUAGE SQL;
 
diff --git a/scripts-available/CDB_ColumnType.sql b/scripts-available/CDB_ColumnType.sql
index eedc4a0..19b8934 100644
--- a/scripts-available/CDB_ColumnType.sql
+++ b/scripts-available/CDB_ColumnType.sql
@@ -3,12 +3,12 @@ CREATE OR REPLACE FUNCTION CDB_ColumnType(REGCLASS, TEXT)
 RETURNS information_schema.character_data
 AS $$
   SELECT
-    pg_catalog.format_type(a.atttypid, NULL)::information_schema.character_data data_type
+    format_type(a.atttypid, NULL)::information_schema.character_data data_type
   FROM pg_class c
-       LEFT JOIN pg_catalog.pg_attribute a ON a.attrelid = c.oid
+       LEFT JOIN pg_attribute a ON a.attrelid = c.oid
   WHERE c.oid = $1::oid
   AND a.attname = $2
-  AND a.attstattarget = -1;
+  AND a.attstattarget < 0; -- exclude system columns
 $$ LANGUAGE SQL;
 
 -- This is to migrate from pre-0.2.0 version
diff --git a/scripts-available/CDB_Overviews.sql b/scripts-available/CDB_Overviews.sql
index 04de527..0e692e7 100644
--- a/scripts-available/CDB_Overviews.sql
+++ b/scripts-available/CDB_Overviews.sql
@@ -522,12 +522,12 @@ AS $$
   SELECT EXISTS (
     SELECT a.attname
     FROM pg_class c
-         LEFT JOIN pg_catalog.pg_attribute a ON a.attrelid = c.oid
-         LEFT JOIN pg_catalog.pg_type t ON t.oid = a.atttypid
+         LEFT JOIN pg_attribute a ON a.attrelid = c.oid
+         LEFT JOIN pg_type t ON t.oid = a.atttypid
     WHERE c.oid = reloid
       AND a.attname = col_name
-      AND pg_catalog.format_type(a.atttypid, NULL) IN ('text', 'character varying', 'character')
-      AND pg_catalog.format_type(a.atttypid, NULL) = pg_catalog.format_type(a.atttypid, a.atttypmod)
+      AND format_type(a.atttypid, NULL) IN ('text', 'character varying', 'character')
+      AND format_type(a.atttypid, NULL) = format_type(a.atttypid, a.atttypmod)
   );
 $$ LANGUAGE SQL STABLE;