Re: [SQLObject] mysql connection losses

[Ian B. <ia...@co...>]

David Warnock wrote:
> Looking at the db api spec and DBAPIConnection I wonder what would 
> happen if we called rollback again in the getConnection.
> 
> In theory there cannot be a transaction in progress as release 
> connection will have already done a commit or rollback.
> 
> So what is the effect of calling rollback, rollback on a connection? I 
> guess we might get an exception which is easy to cope with, but will it 
> do enough for us to know if the connection is valid?

That seems like it might be problematic.  For instance, what if rollback 
is a no-op or something?  It shouldn't be, but I wouldn't feel confident 
that there's not a hidden corner case in the semantics.

> Otherwise it will need to do it in the db specific classes eg for mysql 
> there is conn.ping() for mysql see 
> http://www.esrf.fr/computing/bliss/python2/MySQL/MySQLdb-2.html

That looks like the right thing to use.  Doing it in a database-specific 
way is no problem.  It just requires an additional method call in 
getConnection (say, pingConnection), which by default is a no-op, and we 
override it for the various databases.

   Ian