django mysql connection pinging

[Brian May]

Every time django makes a mysql query, it pings the mysql server. django/db/backends/mysql/base.py:

    def _valid_connection(self):
        if self.connection is not None:
            try:
                self.connection.ping()
                return True
            except DatabaseError:
                self.connection.close()
                self.connection = None
        return False

Not only is this inefficient[1], it is not needed.

I believe this kludge is in case the server connection is closed, e.g. server restarted, or server closed connection as it was idle, or ...

However I have talked to mysql experts, and have been told: "The proper way is as follows: If the connection was lost, a query call will return a specific error, and the client library will reconnect. The app then just needs to re-issue the same query - or in case it was in the middle of a transaction, restart that transaction (obviously)."

Doing a websearch it also seems to be insufficient, there are a number of user's reporting that they get "OperationalError: (2006, 'MySQL server has gone away')" type errors, which suggests Django isn't reconnecting automatically when it should."

I have just received this error myself, from Django 1.5, however still investigating.

I have a vague recollection that this was discussed in a ticket from years ago, however I can't find it now.

Notes:
[1] ​https://groups.google.com/forum/#!topic/django-developers/oIkjJbdWVEo

[Anssi Kääriäinen]

My reading of the 1.6.x and master versions suggest that this has been already fixed. 1.5.x is now in security fixes mode, so we aren't going to backport fixes there.

[Aymeric Augustin]

I cleaned this up when I added persistent connections.