Add comments to existing schema deltas that used "CREATE INDEX" directly

3 files changed, 12 insertions, 0 deletions

diff --git a/synapse/storage/schema/delta/28/events_room_stream.sql b/synapse/storage/schema/delta/28/events_room_stream.sql

index 200c35e6e2..36609475f1 100644
--- a/synapse/storage/schema/delta/28/events_room_stream.sql
+++ b/synapse/storage/schema/delta/28/events_room_stream.sql
@@ -13,4 +13,8 @@
  * limitations under the License.
 */
 
+/** Using CREATE INDEX directly is deprecated in favour of using background
+ * update see synapse/storage/schema/delta/33/access_tokens_device_index.sql
+ * and synapse/storage/registration.py for an example using
+ * "access_tokens_device_index" **/
 CREATE INDEX events_room_stream on events(room_id, stream_ordering);
diff --git a/synapse/storage/schema/delta/28/public_roms_index.sql b/synapse/storage/schema/delta/28/public_roms_index.sql

index ba62a974a4..6c1fd68c5b 100644
--- a/synapse/storage/schema/delta/28/public_roms_index.sql
+++ b/synapse/storage/schema/delta/28/public_roms_index.sql
@@ -13,4 +13,8 @@
  * limitations under the License.
 */
 
+/** Using CREATE INDEX directly is deprecated in favour of using background
+ * update see synapse/storage/schema/delta/33/access_tokens_device_index.sql
+ * and synapse/storage/registration.py for an example using
+ * "access_tokens_device_index" **/
 CREATE INDEX public_room_index on rooms(is_public);
diff --git a/synapse/storage/schema/delta/28/receipts_user_id_index.sql b/synapse/storage/schema/delta/28/receipts_user_id_index.sql

index 452a1b3c6c..cb84c69baa 100644
--- a/synapse/storage/schema/delta/28/receipts_user_id_index.sql
+++ b/synapse/storage/schema/delta/28/receipts_user_id_index.sql
@@ -13,6 +13,10 @@
  * limitations under the License.
  */
 
+/** Using CREATE INDEX directly is deprecated in favour of using background
+ * update see synapse/storage/schema/delta/33/access_tokens_device_index.sql
+ * and synapse/storage/registration.py for an example using
+ * "access_tokens_device_index" **/
 CREATE INDEX receipts_linearized_user ON receipts_linearized(
     user_id
 );