Upgrading

Us well as we also Jooma moodle. our site joomla 2.5 and I would at least update it to the branch 3x my doubt is not about Joomla update, but xed users with Moodle to do this procedure we use a plgin Joomdle that it needs updating. my doubt is the following I have to keep active the plugin and do the transition to version 3x ??? thanks in advance
Marco Z

Better remove Joomdle from Joomla, upgrade to J3.x, and then install Joomdle for J3.x once upgrade is complete.

you have to configure it all again if I uninstall plugins ???? resynchronization

There is no way to upgrade from J2.5 to 3.x keeping Joomdle.
I think configuration will be kept, but it's been a long time since I tried.

what are the tables used by the component joomla ????

Tables are all name #__joomdle_* although you may have all them empty, depending on how you are using Joomdle.

Joomdle main configuration is kept in Joomla extensions table.