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| -rw-r--r-- | changelog.d/15887.misc | 1 | ||||
| -rw-r--r-- | synapse/storage/schema/main/delta/78/05_mitigate_stream_ordering_update_race.py | 70 |
2 files changed, 71 insertions, 0 deletions
diff --git a/changelog.d/15887.misc b/changelog.d/15887.misc new file mode 100644 index 0000000000..7c1005078e --- /dev/null +++ b/changelog.d/15887.misc @@ -0,0 +1 @@ +Fix background schema updates failing over a large upgrade gap. diff --git a/synapse/storage/schema/main/delta/78/05_mitigate_stream_ordering_update_race.py b/synapse/storage/schema/main/delta/78/05_mitigate_stream_ordering_update_race.py new file mode 100644 index 0000000000..1a22f6a404 --- /dev/null +++ b/synapse/storage/schema/main/delta/78/05_mitigate_stream_ordering_update_race.py @@ -0,0 +1,70 @@ +# 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. + + +from synapse.storage.database import LoggingTransaction +from synapse.storage.engines import BaseDatabaseEngine, PostgresEngine + + +def run_create( + cur: LoggingTransaction, + database_engine: BaseDatabaseEngine, +) -> None: + """ + An attempt to mitigate a painful race between foreground and background updates + touching the `stream_ordering` column of the events table. More info can be found + at https://github.com/matrix-org/synapse/issues/15677. + """ + + # technically the bg update we're concerned with below should only have been added in + # postgres but it doesn't hurt to be extra careful + if isinstance(database_engine, PostgresEngine): + select_sql = """ + SELECT 1 FROM background_updates + WHERE update_name = 'replace_stream_ordering_column' + """ + cur.execute(select_sql) + res = cur.fetchone() + + # if the background update `replace_stream_ordering_column` is still pending, we need + # to drop the indexes added in 7403, and re-add them to the column `stream_ordering2` + # with the idea that they will be preserved when the column is renamed `stream_ordering` + # after the background update has finished + if res: + drop_cse_sql = """ + ALTER TABLE current_state_events DROP CONSTRAINT event_stream_ordering_fkey + """ + cur.execute(drop_cse_sql) + + drop_lcm_sql = """ + ALTER TABLE local_current_membership DROP CONSTRAINT event_stream_ordering_fkey + """ + cur.execute(drop_lcm_sql) + + drop_rm_sql = """ + ALTER TABLE room_memberships DROP CONSTRAINT event_stream_ordering_fkey + """ + cur.execute(drop_rm_sql) + + add_cse_sql = """ + ALTER TABLE current_state_events ADD CONSTRAINT event_stream_ordering_fkey + FOREIGN KEY (event_stream_ordering) REFERENCES events(stream_ordering2) NOT VALID; + """ + cur.execute(add_cse_sql) + + add_lcm_sql = """ + ALTER TABLE local_current_membership ADD CONSTRAINT event_stream_ordering_fkey + FOREIGN KEY (event_stream_ordering) REFERENCES events(stream_ordering2) NOT VALID; + """ + cur.execute(add_lcm_sql) + + add_rm_sql = """ + ALTER TABLE room_memberships ADD CONSTRAINT event_stream_ordering_fkey + FOREIGN KEY (event_stream_ordering) REFERENCES events(stream_ordering2) NOT VALID; + """ + cur.execute(add_rm_sql) |