[Cosmo-dev] Data migration for Cosmo 0.6

[Randy Letness]

Ted Leung wrote:
> 1.  What level of support is required?

Ideally we want to be able to take a 0.5 db, and upgrade the schema and 
migrate the data so that Cosmo 0.6 works and there is no data loss. 
Hibernate has some tools that help with the schema migration, but there 
are limitations (upgrading indexes is not supported if I recall).  
Because of the schema changes, the data migration part will have to be 
done using sql scripts or jdbc.

We officially support two databases (Derby and MySQL).  Do we need to 
make sure we support migration for both of these, or are we just 
concerned with MySQL?  I guess high bar is both, low bar MySQL (osaf.us)?

>
> 2.  Is that doable in 1 Randy-week?

I think implementing a migration solution using a combination of 
hibernate tools/ jdbc is doable.  I won' t know exactly until all the 
schema changes for 0.6 are in place.   We could just provide sql scripts 
that could be run against the db, but this would most likely be a manual 
process.  Right now I'm leaning towards jdbc that either gets run on 
startup or as a separate program.

>
> 3. When does that week start/end? (Assuming 2 is true)

I should probably start looking at this after most of the schema changes 
are checked in, which will be in a week or so.  Before moving on to 
implementing sharing support code, I could spend a week on migration.  
That would give us a bunch of time to test things, as we could test 
migration of 0.5 to trunk (0.6) and work out all the bugs.  The only 
concern I have is if that will impact Brian/Morgen if I move sharing 
implementation out a week.

-Randy