1 files changed, 34 insertions, 0 deletions
diff --git a/synapse/_scripts/synapse_port_db.py b/synapse/_scripts/synapse_port_db.py
index d3b4887f69..642fd41629 100755
--- a/synapse/_scripts/synapse_port_db.py
+++ b/synapse/_scripts/synapse_port_db.py
@@ -621,6 +621,25 @@ class Porter:
self.postgres_store.db_pool.updates.has_completed_background_updates()
)
+ @staticmethod
+ def _is_sqlite_autovacuum_enabled(txn: LoggingTransaction) -> bool:
+ """
+ Returns true if auto_vacuum is enabled in SQLite.
+ https://www.sqlite.org/pragma.html#pragma_auto_vacuum
+
+ Vacuuming changes the rowids on rows in the database.
+ Auto-vacuuming is therefore dangerous when used in conjunction with this script.
+
+ Note that the auto_vacuum setting can't be changed without performing
+ a VACUUM after trying to change the pragma.
+ """
+ txn.execute("PRAGMA auto_vacuum")
+ row = txn.fetchone()
+ assert row is not None, "`PRAGMA auto_vacuum` did not give a row."
+ (autovacuum_setting,) = row
+ # 0 means off. 1 means full. 2 means incremental.
+ return autovacuum_setting != 0
+
async def run(self) -> None:
"""Ports the SQLite database to a PostgreSQL database.
@@ -637,6 +656,21 @@ class Porter:
allow_outdated_version=True,
)
+ # For safety, ensure auto_vacuums are disabled.
+ if await self.sqlite_store.db_pool.runInteraction(
+ "is_sqlite_autovacuum_enabled", self._is_sqlite_autovacuum_enabled
+ ):
+ end_error = (
+ "auto_vacuum is enabled in the SQLite database."
+ " (This is not the default configuration.)\n"
+ " This script relies on rowids being consistent and must not"
+ " be used if the database could be vacuumed between re-runs.\n"
+ " To disable auto_vacuum, you need to stop Synapse and run the following SQL:\n"
+ " PRAGMA auto_vacuum=off;\n"
+ " VACUUM;"
+ )
+ return
+
# Check if all background updates are done, abort if not.
updates_complete = (
await self.sqlite_store.db_pool.updates.has_completed_background_updates()
|
