1 files changed, 47 insertions, 2 deletions
diff --git a/synapse/storage/devices.py b/synapse/storage/devices.py
index bc3f575b1e..ecdab34e7d 100644
--- a/synapse/storage/devices.py
+++ b/synapse/storage/devices.py
@@ -22,14 +22,19 @@ from twisted.internet import defer
 
 from synapse.api.errors import StoreError
 from synapse.metrics.background_process_metrics import run_as_background_process
+from synapse.storage.background_updates import BackgroundUpdateStore
 from synapse.util.caches.descriptors import cached, cachedInlineCallbacks, cachedList
 
-from ._base import Cache, SQLBaseStore, db_to_json
+from ._base import Cache, db_to_json
 
 logger = logging.getLogger(__name__)
 
+DROP_DEVICE_LIST_STREAMS_NON_UNIQUE_INDEXES = (
+    "drop_device_list_streams_non_unique_indexes"
+)
 
-class DeviceStore(SQLBaseStore):
+
+class DeviceStore(BackgroundUpdateStore):
     def __init__(self, db_conn, hs):
         super(DeviceStore, self).__init__(db_conn, hs)
 
@@ -52,6 +57,30 @@ class DeviceStore(SQLBaseStore):
             columns=["user_id", "device_id"],
         )
 
+        # create a unique index on device_lists_remote_cache
+        self.register_background_index_update(
+            "device_lists_remote_cache_unique_idx",
+            index_name="device_lists_remote_cache_unique_id",
+            table="device_lists_remote_cache",
+            columns=["user_id", "device_id"],
+            unique=True,
+        )
+
+        # And one on device_lists_remote_extremeties
+        self.register_background_index_update(
+            "device_lists_remote_extremeties_unique_idx",
+            index_name="device_lists_remote_extremeties_unique_idx",
+            table="device_lists_remote_extremeties",
+            columns=["user_id"],
+            unique=True,
+        )
+
+        # once they complete, we can remove the old non-unique indexes.
+        self.register_background_update_handler(
+            DROP_DEVICE_LIST_STREAMS_NON_UNIQUE_INDEXES,
+            self._drop_device_list_streams_non_unique_indexes,
+        )
+
     @defer.inlineCallbacks
     def store_device(self, user_id, device_id,
                      initial_device_display_name):
@@ -757,3 +786,19 @@ class DeviceStore(SQLBaseStore):
             "_prune_old_outbound_device_pokes",
             _prune_txn,
         )
+
+    @defer.inlineCallbacks
+    def _drop_device_list_streams_non_unique_indexes(self, progress, batch_size):
+        def f(conn):
+            txn = conn.cursor()
+            txn.execute(
+                "DROP INDEX IF EXISTS device_lists_remote_cache_id"
+            )
+            txn.execute(
+                "DROP INDEX IF EXISTS device_lists_remote_extremeties_id"
+            )
+            txn.close()
+
+        yield self.runWithConnection(f)
+        yield self._end_background_update(DROP_DEVICE_LIST_STREAMS_NON_UNIQUE_INDEXES)
+        defer.returnValue(1)