2 files changed, 13 insertions, 39 deletions
diff --git a/synapse/storage/monthly_active_users.py b/synapse/storage/monthly_active_users.py
index 0741c7fa61..2337438c58 100644
--- a/synapse/storage/monthly_active_users.py
+++ b/synapse/storage/monthly_active_users.py
@@ -21,41 +21,9 @@ class MonthlyActiveUsersStore(SQLBaseStore):
                 int(self._clock.time_msec()) - (1000 * 60 * 60 * 24 * 30)
             )
 
-            # Query deletes the union of users that have either:
-            #     * not visited in the last 30 days
-            #     * exceeded the total max_mau_value threshold. Where there is
-            #       an excess, more recent users are favoured - this is to cover
-            #       the case where the limit has been step change reduced.
-            #
-            sql = """
-            DELETE FROM monthly_active_users
-            WHERE user_id
-            IN (
-                SELECT * FROM (
-                    SELECT monthly_active_users.user_id
-                    FROM monthly_active_users
-                    LEFT JOIN (
-                        SELECT user_id, max(last_seen) AS last_seen
-                        FROM user_ips
-                        GROUP BY user_id
-                    ) AS uip ON uip.user_id=monthly_active_users.user_id
-                    ORDER BY uip.last_seen desc LIMIT -1 OFFSET ?
-                )
-                UNION
-                SELECT * FROM (
-                    SELECT monthly_active_users.user_id
-                    FROM monthly_active_users
-                    LEFT JOIN (
-                        SELECT user_id, max(last_seen) AS last_seen
-                        FROM user_ips
-                        GROUP BY user_id
-                    ) AS uip  ON uip.user_id=monthly_active_users.user_id
-                    WHERE uip.last_seen < ?
-                )
-            )
-            """
+            sql = "DELETE FROM monthly_active_users WHERE timestamp < ?"
 
-            txn.execute(sql, (self.max_mau_value, thirty_days_ago,))
+            txn.execute(sql, (thirty_days_ago,))
 
         return self.runInteraction("reap_monthly_active_users", _reap_users)
 
@@ -73,18 +41,22 @@ 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(
-            desc="insert_monthly_active_user",
+        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);