[Dev] handling schema and repository format changes

[Andi Vajda]

It seems that for the foreseable future, at least during the 0.5 release 
cycle, the Chandler schema, that is, the core schema and the content model, as 
well as the repository format are going to be changing on a regular basis.

While the repository format doesn't change that frequently, it does so on 
occasion and is going to change several times during this release cycle at 
least for performance reasons.

The core schema has been very stable for a long time now, but I expect changes 
related to the Date/Time types once those have been specified. (Donn, Bryan ?)

The Chandler schema and content model is probably changing on a daily (?) 
basis but that is out of my control.

There are several ways to handle these changes to avoid losing your data 
everytime:

   - use Morgen's PARCELDIR trick to keep parcels of your own, apart from CVS,
     that contain your account info or other test data you might need.
     Morgen handles parcel reloading. See:
     http://wiki.osafoundation.org/twiki/bin/view/Chandler/ParcelLoading

   - write a program of your own that you could invoke from the command line
     and that stuffs the repository with more data of your own. That program
     could create items programmatically, load parcels, or even load native
     XML, if you're so inclined. That format has been very stable too.

I don't expect schema evolution or repository format evolution to be 
implemented for 0.5, it's not even a feature on the list for that release.
It is a problem we need to address for sure, but not for 0.5, at least that
is my understanding (Katie ?).

Andi..