Don't pull out 'last_seen_ts' always

synapse/handlers/admin.py

@@ -76,7 +76,6 @@ async def get_user(self, user: UserID) -> Optional[JsonDict]:
             "consent_ts",
             "user_type",
             "is_guest",
-            "last_seen_ts",
         }
 
         if self._msc3866_enabled:
@@ -105,6 +104,9 @@ async def get_user(self, user: UserID) -> Optional[JsonDict]:
         user_info_dict["external_ids"] = external_ids
         user_info_dict["erased"] = await self._store.is_user_erased(user.to_string())
 
+        last_seen_ts = await self._store.get_last_seen_for_user_id(user.to_string())
+        user_info_dict["last_seen_ts"] = last_seen_ts
+
         return user_info_dict
 
     async def export_user_data(self, user_id: str, writer: "ExfiltrationWriter") -> Any:

synapse/storage/databases/main/client_ips.py

@@ -764,3 +764,14 @@ async def get_user_ip_and_agents(
                     }
 
         return list(results.values())
+
+    async def get_last_seen_for_user_id(self, user_id: str) -> Optional[int]:
+        """Get the last seen timestamp for a user, if we have it."""
+
+        return await self.db_pool.simple_select_one_onecol(
+            table="user_ips",
+            keyvalues={"user_id": user_id},
+            retcol="MAX(last_seen)",
+            allow_none=True,
+            desc="get_last_seen_for_user_id",
+        )

synapse/storage/databases/main/registration.py

@@ -206,12 +206,8 @@ def get_user_by_id_txn(txn: LoggingTransaction) -> Optional[Dict[str, Any]]:
                     consent_server_notice_sent, appservice_id, creation_ts, user_type,
                     deactivated, COALESCE(shadow_banned, FALSE) AS shadow_banned,
                     COALESCE(approved, TRUE) AS approved,
-                    COALESCE(locked, FALSE) AS locked, last_seen_ts
+                    COALESCE(locked, FALSE) AS locked
                 FROM users
-                LEFT JOIN (
-                    SELECT user_id, MAX(last_seen) AS last_seen_ts
-                    FROM user_ips GROUP BY user_id
-                ) ls ON users.name = ls.user_id
                 WHERE name = ?
                 """,
                 (user_id,),