From e4fa3ba0f2410402453a50bc9a8372e2da1270a2 Mon Sep 17 00:00:00 2001
From: Richard van der Hoff <richard@matrix.org>
Date: Fri, 1 May 2020 09:47:32 +0100
Subject: [PATCH 1/2] Wait for current_state_events_membership before
 populate_stats_process_rooms

---
 changelog.d/7387.bugfix                                     | 1 +
 .../data_stores/main/schema/delta/56/stats_separated.sql    | 6 +++++-
 2 files changed, 6 insertions(+), 1 deletion(-)
 create mode 100644 changelog.d/7387.bugfix

diff --git a/changelog.d/7387.bugfix b/changelog.d/7387.bugfix
new file mode 100644
index 000000000000..a250517b4958
--- /dev/null
+++ b/changelog.d/7387.bugfix
@@ -0,0 +1 @@
+Fix a bug which would cause the room durectory to be incorrectly populated if Synapse was upgraded directly from v1.2.1 or earlier to v1.4.0 or later. Note that this fix does not apply retrospectively; see the [upgrade notes](UPGRADE.rst#upgrading-to-v1130) for more information.
diff --git a/synapse/storage/data_stores/main/schema/delta/56/stats_separated.sql b/synapse/storage/data_stores/main/schema/delta/56/stats_separated.sql
index 163529c071e3..bbdde121e896 100644
--- a/synapse/storage/data_stores/main/schema/delta/56/stats_separated.sql
+++ b/synapse/storage/data_stores/main/schema/delta/56/stats_separated.sql
@@ -35,9 +35,13 @@ DELETE FROM background_updates WHERE update_name IN (
     'populate_stats_cleanup'
 );
 
+-- this relies on current_state_events.membership having been populated, so add
+-- a dependency on current_state_events_membership.
 INSERT INTO background_updates (update_name, progress_json, depends_on) VALUES
-    ('populate_stats_process_rooms', '{}', '');
+    ('populate_stats_process_rooms', '{}', 'current_state_events_membership');
 
+-- this also relies on current_state_events.membership having been populated, but
+-- we get that as a side-effect of depending on populate_stats_process_rooms.
 INSERT INTO background_updates (update_name, progress_json, depends_on) VALUES
     ('populate_stats_process_users', '{}', 'populate_stats_process_rooms');
 

From b0848c08e828c053a3c3c37353b95f82fd7c1db6 Mon Sep 17 00:00:00 2001
From: Richard van der Hoff <richard@matrix.org>
Date: Fri, 1 May 2020 10:35:07 +0100
Subject: [PATCH 2/2] mend

---
 UPGRADE.rst | 31 +++++++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)

diff --git a/UPGRADE.rst b/UPGRADE.rst
index 768d94a393a4..d1408be2af47 100644
--- a/UPGRADE.rst
+++ b/UPGRADE.rst
@@ -75,6 +75,37 @@ for example:
      wget https://packages.matrix.org/debian/pool/main/m/matrix-synapse-py3/matrix-synapse-py3_1.3.0+stretch1_amd64.deb
      dpkg -i matrix-synapse-py3_1.3.0+stretch1_amd64.deb
 
+Upgrading to v1.13.0
+====================
+
+Incorrect database migration in old synapse versions
+----------------------------------------------------
+
+A bug was introduced in Synapse 1.4.0 which could cause the room directory to
+be incomplete or empty if Synapse was upgraded directly from v1.2.1 or earlier,
+to versions between v1.4.0 and v1.12.x.
+
+This will *not* be a problem for Synapse installations which were:
+ * created at v1.4.0 or later,
+ * upgraded via v1.3.x, or
+ * upgraded straight from v1.2.1 or earlier to v1.13.0 or later.
+
+If completeness of the room directory is a concern, installations which are
+affected can be repaired as follows:
+
+1. Run the following sql from a `psql` or `sqlite3` console:
+
+   .. code:: sql
+
+     INSERT INTO background_updates (update_name, progress_json, depends_on) VALUES
+        ('populate_stats_process_rooms', '{}', 'current_state_events_membership');
+
+     INSERT INTO background_updates (update_name, progress_json, depends_on) VALUES
+        ('populate_stats_process_users', '{}', 'populate_stats_process_rooms');
+
+2. Restart synapse.
+
+
 Upgrading to v1.12.0
 ====================