Possible update failure due to autocommit

[V.E.O@…]

One failed autocommit defect in trac/cache.py. This defect happens when I migrate trac into MySQL NDB Engine environment.

Code sample start from line 186 in trac/cache.py:

            def do_invalidate(db):
                cursor = db.cursor()
                cursor.execute("""
                    UPDATE cache SET generation=generation+1 WHERE id=%s
                    """, (id,))
                cursor.execute("SELECT generation FROM cache WHERE id=%s",
                               (id,))
                if not cursor.fetchone():
                    cursor.execute("INSERT INTO cache VALUES (%s, %s)",
                                   (id, 0))

I tried open autocommit mode in NDB engine, still update operation is not commited before select. Even defaulty mysqldb disabled autocommit.​http://mysql-python.sourceforge.net/FAQ.html

Is it suitable to add explicitly cursor.commit() between update and select ?

[anonymous]

invalid, I figure out it is not problem of commit. still NDB varchar limit problem, please close this.

[Christian Boos]

Fine. Thanks for the feedback!

You may want to provide additional feedback concerning the NDB limits in #8567.