Storm 0.13

Yesterday, Thomas rolled the 0.13 release of Storm, which can be downloaded from Launchpad. Storm is the object relational mapper for Python used by Launchpad and Landscape, so it is capable of supporting quite large scale applications. It is seven months since the last release, so there is a lot of improvements. Here are a few simple statistics:

0.12 0.13 Change
Tarball size (KB) 117 155 38
Mainline revisions 213 262 49
Revisions in ancestry 552 875 323

So it is a fairly significant update by any of these metrics. Among the new features are:

  • Infrastructure for tracing the SQL statements issued by Storm. Sample tracer implementations are provided to implement bounded statement run times and for logging statements (both features used for QA of Launchpad).
  • A validation framework. The property constructors take a validator keyword argument, which should be a function taking arguments (object, attr_name, value) and return the value to set. If the function raises an exception, it can prevent a value from being set. By returning something different to its third argument it can transform values.
  • The find() and ResultSet API has been extended to make it possible to generate queries that use GROUP BY and HAVING. The primary use case for result sets that contain an object plus some aggregates associated with that object.
  • Some core parts of Storm have been accelerated through a C extension. This code is turned off by default, but can be enabled by defining the STORM_CEXTENSIONS environment variable to 1. While it is disabled by default, it is pretty stable. Barring any serious problems reported over the next release cycle, I'd expect it to be enabled by default for the next release.
  • The minimum dependencies of the storm.zope.zstorm module have been reduced to just the zope.interface and transaction modules. This makes it easier to use the per-thread store management code and global transaction management outside of Zope apps (e.g. for integrating with Django).

It doesn't include my Django integration code though, since that isn't fully baked. I'll post some more about that later.