How to handle Play Framework 2 database evolutions in production
Unfortunately Ebean
can create only CREATE DDL
(and not UPDATE DDL
) (as answered on their group), therefore you need to switch to manual evolutions ASAP.
some rules:
- Always backup your live DB before implementing any changes :)
- ebean plugin recreates whole DDL if it has only
1.sql
evolution created by it - You need to remove two first comments from
1.sql
and start to writing own evolutions with next numbers2.sql
,3.sql
etc. Try to place as many models/fields as possible before switching to manual evolutions. The biggest part will be done automatically by plugin. - manual evolutions should contain
ALTERS
to existing tables/columns instead of DROP/CREATE, they should have both:Ups
andDowns
for each change. - try to place as many changes in each evolution as possible, it's easier to manage then writing separate evolution for each small change.
De facto sometimes it's just easier to modify DB structure with DB gui, anyway it works mainly for the single developer... when you need to share your code with other developers writing evolutions will be better option.
If after some time you'll add next 'big' portion of new models you can enable temporary auto DDL again and using local git just to copy new parts. Then revert to own revolution and paste new parts generated by Ebean plugin.
Biesior basically summed it up quite well. However, as a beginner in Play, I find that a bit more clarification with a concrete example might be helpful.
First, the following example is for Java.
Suppose you added a new field
public String dum_str;
in your model Dum. Then, you will need a 2.sql
under conf/evolutions/
like this:
# --- !UpsALTER TABLE dum ADD COLUMN dum_str VARCHAR(255);# --- !DownsALTER TABLE dum DROP dum_str;
I hope this would be helpful.