diff --git a/synapse/storage/background_updates.py b/synapse/storage/background_updates.py
index 813ad59e56..d4cf0fc59b 100644
--- a/synapse/storage/background_updates.py
+++ b/synapse/storage/background_updates.py
@@ -228,46 +228,69 @@ class BackgroundUpdateStore(SQLBaseStore):
columns (list[str]): columns/expressions to include in index
"""
- # if this is postgres, we add the indexes concurrently. Otherwise
- # we fall back to doing it inline
- if isinstance(self.database_engine, engines.PostgresEngine):
- conc = True
- else:
- conc = False
- # We don't use partial indices on SQLite as it wasn't introduced
- # until 3.8, and wheezy has 3.7
- where_clause = None
-
- sql = (
- "CREATE INDEX %(conc)s %(name)s ON %(table)s (%(columns)s)"
- " %(where_clause)s"
- ) % {
- "conc": "CONCURRENTLY" if conc else "",
- "name": index_name,
- "table": table,
- "columns": ", ".join(columns),
- "where_clause": "WHERE " + where_clause if where_clause else ""
- }
-
- def create_index_concurrently(conn):
+ def create_index_psql(conn):
conn.rollback()
# postgres insists on autocommit for the index
conn.set_session(autocommit=True)
- c = conn.cursor()
- c.execute(sql)
- conn.set_session(autocommit=False)
- def create_index(conn):
+ try:
+ c = conn.cursor()
+
+ # If a previous attempt to create the index was interrupted,
+ # we may already have a half-built index. Let's just drop it
+ # before trying to create it again.
+
+ sql = "DROP INDEX IF EXISTS %s" % (index_name,)
+ logger.debug("[SQL] %s", sql)
+ c.execute(sql)
+
+ sql = (
+ "CREATE INDEX CONCURRENTLY %(name)s ON %(table)s"
+ " (%(columns)s) %(where_clause)s"
+ ) % {
+ "name": index_name,
+ "table": table,
+ "columns": ", ".join(columns),
+ "where_clause": "WHERE " + where_clause if where_clause else ""
+ }
+ logger.debug("[SQL] %s", sql)
+ c.execute(sql)
+ finally:
+ conn.set_session(autocommit=False)
+
+ def create_index_sqlite(conn):
+ # Sqlite doesn't support concurrent creation of indexes.
+ #
+ # We don't use partial indices on SQLite as it wasn't introduced
+ # until 3.8, and wheezy has 3.7
+ #
+ # We assume that sqlite doesn't give us invalid indices; however
+ # we may still end up with the index existing but the
+ # background_updates not having been recorded if synapse got shut
+ # down at the wrong moment - hance we use IF NOT EXISTS. (SQLite
+ # has supported CREATE TABLE|INDEX IF NOT EXISTS since 3.3.0.)
+ sql = (
+ "CREATE INDEX IF NOT EXISTS %(name)s ON %(table)s"
+ " (%(columns)s)"
+ ) % {
+ "name": index_name,
+ "table": table,
+ "columns": ", ".join(columns),
+ }
+
c = conn.cursor()
+ logger.debug("[SQL] %s", sql)
c.execute(sql)
+ if isinstance(self.database_engine, engines.PostgresEngine):
+ runner = create_index_psql
+ else:
+ runner = create_index_sqlite
+
@defer.inlineCallbacks
def updater(progress, batch_size):
logger.info("Adding index %s to %s", index_name, table)
- if conc:
- yield self.runWithConnection(create_index_concurrently)
- else:
- yield self.runWithConnection(create_index)
+ yield self.runWithConnection(runner)
yield self._end_background_update(update_name)
defer.returnValue(1)
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