This might be too broad, but it’s a problem I’m having a bear of a time dealing with. We have an application that we distribute to our end users. It’s running on top of a derby back end. We can push out code changes fairly easily, it’ll go out to our server, see there’s a new version, download, overwrite old code, and reboot.
But, as we change our code, we also alter the schema of the derby database. We don’t have great methods to update this. Currently we can push SQL updates via FTP. When the program is connected to the internet, it looks for new SQL files, downloads them and runs.
Unfortunately a lot of our clients have limited Internet access, so they get these updates intermittently. Sometimes because they changes are big enough, their local DB schema gets out of sync with what we want. Or they get the code changes via CD but not the SQL changes (someone mails them the CD).
What I’ve been trying to do is create a SOAP service that can serve up XML representations of the schema. It’s been a huge PITA to develop so far.
What are some methods people are currently using to maintain databases like this? I feel like I’m not the first to do this, so there might be better ways than what I’m doing.
Based on some comments here, here’s an update:
Basically, I think we screwed ourselves early on by not adhering to a strict versioning of the DB, so I don’t know how everyone’s DB is at. A lot of people got custom installs built (groan at will). I need a tool that can tell the differences between their DB and a “official” copy.
I have a tool built, it kind of works, but there’s so…many…things to keep track of.
Can you distribute the DB changes as part of the code changes? Then, when the app restarts, it checks if it needs to run any updates on the DB.
Obviously, you’ll need to version the DB schema to avoid applying the same update more than once.
I know some applications that do this (mostly in Ruby, but also in Java).