What data will be lost during upgrade from Ubuntu 12.04 LTS to 14.04?

Presently running Ubuntu 12.04 LTS 64 bit with lots of other software. List of other software are listed below which I use most.

1. Oracle JDK


2. Apache HTTP server


3. Tomcat


4. MySql


5. PostgreSQL


6. Few Cron jobs using crontab


7. Darktable


8. Gimp

Few of them installed using apt-get and others are installed from source inside /opt directory.

Now my questions are, if I upgrade my system to 14.04 LTS using update manager prompt, what data will be lost? Do I have to install those software all over again? AFAIK /home will be preserved. Need to confirm.

Update:
Done online upgrade from 12.04 to 14.04 and everything is in place. No data is lost, All the mentioned softwares including database are working fine. Every customisation is in place.

Best option is to make an image of the current disk. Test it to make sure it works.

• Your homefolder won't be changed, or: should not be changed.


• Gimp: settings are in your home folder.


• Apache, PHP, MySQL, Postgres, Tomcat: upgrades may break what you run on your machine. I can't tell it from here, it's a matter of testing. Something may depend on a function that is not available anymore, and it will break.


• Backup folders and files in /etc where config files for Apache etc are located. You can backup the entire /etc folder as it's probably not too big. You need to be root to do this. Do this with tar, and be sure to preserve rights and ownership.


• Cron jobs should stay the same, back them up if you're not sure.

The upgrade program may ask you what to do with the Apache config file(s): overwrite, keep? You should keep them. Same for other config files: keep them.