diff --git a/migrations/schema.sql b/migrations/schema.sql
index 852d7e82f..134f87ded 100644
--- a/migrations/schema.sql
+++ b/migrations/schema.sql
@@ -200,7 +200,7 @@ CREATE TABLE IF NOT EXISTS subdomains(
     appId VARCHAR(128) NOT NULL,
     domain VARCHAR(128) NOT NULL,
     subdomain VARCHAR(128) NOT NULL,
-    type VARCHAR(128) NOT NULL,
+    type VARCHAR(128) NOT NULL, /* primary or redirect */
 
     FOREIGN KEY(domain) REFERENCES domains(domain),
     FOREIGN KEY(appId) REFERENCES apps(id),