In a new post to his site Benjamin Eberlei takes a look at the idea of "feature flags" (settings to turn on and off major features) and how they can be used with Doctrine entities to handle sync issues between new properties and the database schema.
The problem of feature flags with Doctrine is easily explained: If you add properties for a new feature that is disabled in the Doctrine metadata, then you need to upgrade the database before deployment, even when the feature is not being rolled out for some days/weeks. Doctrine requires the database to look exactly like the metadata specifies it.
His solution was to use the "loadClassMetadata" event in the entity to dynamically append these new properties based on simple "if" checks of feature flags in the configuration object. Obviously using this is a bit of a hack until the new properties are in place, but once they are then the only change is removing this code.