diff --git a/synapse/storage/schema/README.md b/synapse/storage/schema/README.md
index 030153db64..729f44ea6c 100644
--- a/synapse/storage/schema/README.md
+++ b/synapse/storage/schema/README.md
@@ -1,37 +1,4 @@
# Synapse Database Schemas
-This directory contains the schema files used to build Synapse databases.
-
-Synapse supports splitting its datastore across multiple physical databases (which can
-be useful for large installations), and the schema files are therefore split according
-to the logical database they are apply to.
-
-At the time of writing, the following "logical" databases are supported:
-
-* `state` - used to store Matrix room state (more specifically, `state_groups`,
- their relationships and contents.)
-* `main` - stores everything else.
-
-Addionally, the `common` directory contains schema files for tables which must be
-present on *all* physical databases.
-
-## Full schema dumps
-
-In the `full_schemas` directories, only the most recently-numbered snapshot is useful
-(`54` at the time of writing). Older snapshots (eg, `16`) are present for historical
-reference only.
-
-## Building full schema dumps
-
-If you want to recreate these schemas, they need to be made from a database that
-has had all background updates run.
-
-To do so, use `scripts-dev/make_full_schema.sh`. This will produce new
-`full.sql.postgres` and `full.sql.sqlite` files.
-
-Ensure postgres is installed, then run:
-
- ./scripts-dev/make_full_schema.sh -p postgres_username -o output_dir/
-
-NB at the time of writing, this script predates the split into separate `state`/`main`
-databases so will require updates to handle that correctly.
+This directory contains the schema files used to build Synapse databases. For more
+information, see /docs/development/database_schema.md.
diff --git a/synapse/storage/schema/__init__.py b/synapse/storage/schema/__init__.py
index f0d9f23167..d36ba1d773 100644
--- a/synapse/storage/schema/__init__.py
+++ b/synapse/storage/schema/__init__.py
@@ -12,6 +12,21 @@
# See the License for the specific language governing permissions and
# limitations under the License.
-# Remember to update this number every time a change is made to database
-# schema files, so the users will be informed on server restarts.
SCHEMA_VERSION = 59
+"""Represents the expectations made by the codebase about the database schema
+
+This should be incremented whenever the codebase changes its requirements on the
+shape of the database schema (even if those requirements are backwards-compatible with
+older versions of Synapse).
+
+See `README.md <synapse/storage/schema/README.md>`_ for more information on how this
+works.
+"""
+
+
+SCHEMA_COMPAT_VERSION = 59
+"""Limit on how far the synapse codebase can be rolled back without breaking db compat
+
+This value is stored in the database, and checked on startup. If the value in the
+database is greater than SCHEMA_VERSION, then Synapse will refuse to start.
+"""
diff --git a/synapse/storage/schema/common/schema_version.sql b/synapse/storage/schema/common/schema_version.sql
index 42e5cb6df5..f41fde5d2d 100644
--- a/synapse/storage/schema/common/schema_version.sql
+++ b/synapse/storage/schema/common/schema_version.sql
@@ -20,6 +20,13 @@ CREATE TABLE IF NOT EXISTS schema_version(
CHECK (Lock='X')
);
+CREATE TABLE IF NOT EXISTS schema_compat_version(
+ Lock CHAR(1) NOT NULL DEFAULT 'X' UNIQUE, -- Makes sure this table only has one row.
+ -- The SCHEMA_VERSION of the oldest synapse this database can be used with
+ compat_version INTEGER NOT NULL,
+ CHECK (Lock='X')
+);
+
CREATE TABLE IF NOT EXISTS applied_schema_deltas(
version INTEGER NOT NULL,
file TEXT NOT NULL,
diff --git a/synapse/storage/schema/main/delta/59/11add_knock_members_to_stats.sql b/synapse/storage/schema/main/delta/59/11add_knock_members_to_stats.sql
new file mode 100644
index 0000000000..56c0ad0003
--- /dev/null
+++ b/synapse/storage/schema/main/delta/59/11add_knock_members_to_stats.sql
@@ -0,0 +1,17 @@
+/* Copyright 2020 Sorunome
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+ALTER TABLE room_stats_current ADD COLUMN knocked_members INT NOT NULL DEFAULT '0';
+ALTER TABLE room_stats_historical ADD COLUMN knocked_members BIGINT NOT NULL DEFAULT '0';
\ No newline at end of file
|
