2 files changed, 10 insertions, 4 deletions
diff --git a/synapse/storage/monthly_active_users.py b/synapse/storage/monthly_active_users.py
index 7b3f13aedf..03eeea792e 100644
--- a/synapse/storage/monthly_active_users.py
+++ b/synapse/storage/monthly_active_users.py
@@ -38,18 +38,22 @@ class MonthlyActiveUsersStore(SQLBaseStore):
             return count
         return self.runInteraction("count_users", _count_users)
 
-    def insert_monthly_active_user(self, user_id):
+    def upsert_monthly_active_user(self, user_id):
         """
             Updates or inserts monthly active user member
             Arguments:
                 user_id (str): user to add/update
         """
-        return self._simple_insert(
+        return self._simple_upsert(
             desc="upsert_monthly_active_user",
             table="monthly_active_users",
-            values={
+            keyvalues={
                 "user_id": user_id,
             },
+            values={
+                "timestamp": int(self._clock.time_msec()),
+            },
+            lock=False,
         )
 
     @defer.inlineCallbacks
diff --git a/synapse/storage/schema/delta/51/monthly_active_users.sql b/synapse/storage/schema/delta/51/monthly_active_users.sql
index 590b1abab2..f2b6d3e31e 100644
--- a/synapse/storage/schema/delta/51/monthly_active_users.sql
+++ b/synapse/storage/schema/delta/51/monthly_active_users.sql
@@ -15,7 +15,9 @@
 
 -- a table of monthly active users, for use where blocking based on mau limits
 CREATE TABLE monthly_active_users (
-    user_id TEXT NOT NULL
+    user_id TEXT NOT NULL,
+    timestamp BIGINT NOT NULL
 );
 
 CREATE UNIQUE INDEX monthly_active_users_users ON monthly_active_users(user_id);
+CREATE INDEX monthly_active_users_time_stamp ON monthly_active_users(timestamp);