[Koha-devel] Rolling DB upgrades

[Julian Maurice]

Le 03/03/2021 à 09:44, Joonas Kylmälä a écrit :
> I don't know any other software but not sure it is that difficult. What
> I gather, we could use e.g. Jenkins to push the code / new debian
> package that would be created for every commit. Jenkins would make sure
> db schema migration is finished before installing a newer version and
> the steps would be repeated until we are at the latest release.

I'm not too much concerned about the "push-test-release" process, but 
more about how we consistently make the code aware of the multiple 
possible database states. Surely we'd have to enforce a new set of rules 
for writing database updates. And we'd have to test these changes very 
carefully, since a tiny mistake could mean a loss of data. Of course you 
have backups, but DB rollback means downtime, right ?
So, that sounds like a lot of extra work for avoiding a few seconds of 
downtime (most of the time).
That being said, I'm really interested in seeing an actual working 
implementation :)

Also, what about template translations ? It takes some time to generate 
translated templates, and it can do weird things if the new code is used 
while using the old templates (or the old code with the new templates). 
Wouldn't that prevent zero-downtime upgrade ?

-- 
Julian Maurice
BibLibre