[cosmo-dev] 0.9 post mortem

[Randy Letness]

Bobby Rullo wrote:
> Here's some thoughts I've had after the 0.9.0 Revert/Data Loss Fiasco 
> of 07
>
> 1) We should have DB Revert scripts. This doesn't mean a script which 
> reverts to the backup. What I am talking about is a script which
>     i) Makes a post-update backup of the database
>     ii) Migrates the database backwards to the old (previous release) 
> schema

This would be nice.  In fact the schema changes in 0.9 were small enough 
that we could have done a revert with a single update statement.  But in 
past migrations a revert script would have been more complicated, and 
this is something that would have to be tested too.  I should have 
thought of the revert option during the fiasco but I had to leave at the 
exact moment stuff started to blow up.  It would have been nice to have 
had more time but I didn't know when the update was going to happen.

> Obviously this is only for releases which have a schema change. I'm 
> not saying that we have to have this for every database we support - 
> just for hub. Maybe it's not even the Cosmo team's job, maybe it's Hub 
> (working with Cosmo team of course)
>
> 2) I don't think we should have any release dependent on roving 
> "SNAPSHOT" - it makes bugs difficult to reproduce, since you 
> potentially get a different build every day. When we test an RC, we 
> should pin to that day's SNAPSHOT.

+1 We ran into this before with ical4j...should have learned our 
lesson..doh!

> 3) I'm not sure to what extent we are doing this, but we need to make 
> sure to test on a cosmo instance with migrated data. This testing may 
> or may not include the normal windmill stuff, but it should have added 
> performance stuff, so we know if things are way out of wack.

+1  Although in this case, because we were using SNAPSHOT dependencies, 
each test may have been using different code...doh!

-Randy