This sounds like yet another item which should go into the dbapi 3.0 spec... as soon as someone has the courage to start one. -- Vernon
On Mon, Sep 12, 2011 at 4:20 PM, Chris Clark <chris.cl...@ingres.com> wrote: > Hi All, > > I was discussing with someone today autocommit support and found an area of > pep-249 where I think we could improve the wording (and the spec): > > http://www.python.org/dev/peps/pep-0249/ > > ..... > > .commit() > Commit any pending transaction to the database. Note that > if the database supports an auto-commit feature, this must > be initially off. An interface method may be provided to > turn it back on. > > ..... > > It is the last sentence that I'm looking at: > >> An interface method may be provided to turn it back on. > > Comments: > > * The "may" clearly marks this as an optional interface (and I'm > happy about that). > * It would be helpful to make clear what the interface method would > be so module authors can implement this consistently > * if autocommit can be turned on in a connection, there should have > a way to turn it off again > > > Here are some examples of the "interface method" implemented out in the wild > today > > * It looks like mxodbc handles this as a setconnectoption() method > on the connection. > http://www.egenix.com/products/python/mxODBCConnect/doc/mxodbc/ > * a number of other ODBC based drivers offer an option in the > connect() constructor (only) > * The mysql module <http://mysql-python.sourceforge.net/> implies it > has an method on the connection object for this conn.autocommit(), > but this does not appear to be available in the pep-249 compatible > API <http://mysql-python.sourceforge.net/MySQLdb-1.2.2/>! > > > Obviously there is plenty of scope for different implementations. I think > there is value in documenting a recommendation on what this interface should > look like. > > I like the API approach mxodbc has taken (it matches ODBC very well) but it > doesn't feel Pythonic :-( > > To get the ball rolling, here is an initial suggestion: > > * needs to take a boolean flag as a parameter to enable and also disable > * needs to return the auto commit state so it can be queried > > pep changes, marked between ** and **: > > Connection Objects > > Connection Objects should respond to the following methods: > ...... > > .commit() > Commit any pending transaction to the database. Note that > if the database supports an auto-commit feature, this must > be initially off. **See the option autocommit() method to change > autocommit behavior.** > Database modules that do not support transactions > should > implement this method with void functionality. > > ..... > ** > Connection Objects may optional implement and respond to the following > methods: > > autocommit(on=None) > returns True when autocommit is on, and False when autocommit is off. > If the keyword parameter "on" is set to True, the connection will > commit any open transactions (as if connection.commit() was issued) and all > subsequent transactions will auto commit, the method returns True if > successfully in autocommit mode. > If the keyword parameter "on" is set to False, the connection will > commit any open transactions (as if connection.commit() was issued) and all > subsequent transactions will no longer auto commit, the method returns False > if successfully out of autocommit mode.. > ** > > The reason for the immediate commit is to try and avoid DBMS specific > behaviors (read error conditions) with different vendors when an auto commit > is requested with open transactions. > > Comments? > > > Chris > > _______________________________________________ > DB-SIG maillist - DB-SIG@python.org > http://mail.python.org/mailman/listinfo/db-sig > _______________________________________________ DB-SIG maillist - DB-SIG@python.org http://mail.python.org/mailman/listinfo/db-sig
