diff --git a/test/CDB_DistTypeTest.sql b/test/CDB_DistTypeTest.sql
new file mode 100644
index 0000000..efe1804
--- /dev/null
+++ b/test/CDB_DistTypeTest.sql
@@ -0,0 +1,4 @@
+WITH data AS (
+    SELECT pow(x,3)::numeric x FROM generate_series(-100,100) x
+    ) 
+SELECT CDB_DistType(array_agg(x)) FROM data
diff --git a/test/CDB_DistTypeTest_expect b/test/CDB_DistTypeTest_expect
new file mode 100644
index 0000000..f70f10e
--- /dev/null
+++ b/test/CDB_DistTypeTest_expect
@@ -0,0 +1 @@
+A