I'm needing to make sure that I have clear process for upgrading
databases when I need to use a future version of Derby (e.g when 10.3
comes out). I need to ensure that all current databases in use will be
seemlessly and safely updated. In my application each user will have one
or many (embedded) databases, each of which will need upgrading.
I understand that:
1. production versions of Derby will update from earlier production
versions.
2. a "soft" upgrade can be performed allowing the newer version of derby
to run against the old database files
3. a "hard" upgrade can be performed by specifying upgrade=true as a
connection param which will update the database files to the new format.
I assume if would be good practice to allow a backup of the database
before upgrading. To do this I need to determine if an upgrade is going
to be needed, but I presumably can't do this until I've connected to the
db. I also need to know whether an upgrade is goign to be needed so that
the upgrade=true param can be supplied. So my options would see to be:
Either: store the version info as a external property which will be
consulted prior to connecting to the db.
Or: connect using a soft upgrade, detect that the database needs to be
updated (how do I do this? - will the DatabaseMetaData report the old
version number or the new one?), perform the backup, and then ask user
to restart so that connection can be made again and the "hard" upgrade
performed.
Will the second approach work?
Any other issues to consider?
Many thanks
Tim
