Use native UPSERTs where possible (#4306)

1 files changed, 14 insertions, 0 deletions

diff --git a/synapse/storage/engines/postgres.py b/synapse/storage/engines/postgres.py
index 42225f8a2a..4004427c7b 100644
--- a/synapse/storage/engines/postgres.py
+++ b/synapse/storage/engines/postgres.py
@@ -38,6 +38,13 @@ class PostgresEngine(object):
         return sql.replace("?", "%s")
 
     def on_new_connection(self, db_conn):
+
+        # Get the version of PostgreSQL that we're using. As per the psycopg2
+        # docs: The number is formed by converting the major, minor, and
+        # revision numbers into two-decimal-digit numbers and appending them
+        # together. For example, version 8.1.5 will be returned as 80105
+        self._version = db_conn.server_version
+
         db_conn.set_isolation_level(
             self.module.extensions.ISOLATION_LEVEL_REPEATABLE_READ
         )
@@ -54,6 +61,13 @@ class PostgresEngine(object):
 
         cursor.close()
 
+    @property
+    def can_native_upsert(self):
+        """
+        Can we use native UPSERTs? This requires PostgreSQL 9.5+.
+        """
+        return self._version >= 90500
+
     def is_deadlock(self, error):
         if isinstance(error, self.module.DatabaseError):
             # https://www.postgresql.org/docs/current/static/errcodes-appendix.html