Permalinks how it works if move webiste

Hi Everyone,

I have a question, I’ll try to make it clear 🙂

Well right now I have a blog with around 1000 posts and I would like to move the website to another platform, the blog grow so much and I need to take it to the next level and I would like to use Joomla and create a community.

So my concern is the following.
Right now my permalinks are configured as /%year%/%monthnum%/%postname%/ but I want Joomla to have the following URL structure: http://www.site.com/category/postname. Google has already indexed the links with the actual structure /%year%/%monthnum%/%postname%/, if I change the permalink strucuture to /%category%/%postname%/ and if I type the url http://www.site.com/category/postname it works. So I would like o know if WordPress stores the permalinks in the database or if all it does is it takes post_name and ads the parameters /%year%/%monthnum%/ to the link?

Thank you very much in advance for your help.