Yesterday Federico released version 2.0.7 of psycopg2 (a Python database adapter for PostgreSQL). I made a fair number of the changes in this release to make it more usable for some of Canonical‘s applications. The new release should work with the development version of Storm, and shouldn’t be too difficult to get everything working with other frameworks.
Some of the improvements include:
- Better selection of exceptions based on the SQLSTATE result field. This causes a number of errors that were reported as ProgrammingError to use a more appropriate exception (e.g. DataError, OperationalError, InternalError). This was the change that broke Storm’s test suite as it was checking for ProgrammingError on some queries that were clearly not programming errors.
- Proper error reporting for commit() and rollback(). These methods now use the same error reporting code paths as execute(), so an integrity error on commit() will now raise IntegrityError rather than OperationalError.
- The compile-time switch that controls whether the display_size member of Cursor.description is calculated is now turned off by default. The code was quite expensive and the field is of limited use (and not provided by a number of other database adapters).
- New QueryCanceledError and TransactionRollbackError exceptions. The first is useful for handling queries that are canceled by statement_timeout. The second provides a convenient way to catch serialisation failures and deadlocks: errors that indicate the transaction should be retried.
- Fixes for a few memory leaks and GIL misuses. One of the leaks was in the notice processing code that could be particularly problematic for long-running daemon processes.
- Better test coverage and a driver script to run the entire test suite in one go. The tests should all pass too, provided your database cluster uses unicode (there was a report just before the release of one test failing for a LATIN1 cluster).
If you’re using previous versions of psycopg2, I’d highly recommend upgrading to this release.
Future work will probably involve support for the DB-API two phase commit extension, but I don’t know when I’ll have time to get to that.