I have had a WordPress site for two years. It is hosted on a typical WAMP server. I would change it's theme but the one I have chosen doesn't work with the qTranslate or mqTranslate plugin. I'm forced to change the plugin and use polylang because the new theme uses a pagebuilder.
Due the different way those plugins manage translations (one page VS multiple pages), the only solution I have is copy and paste my contents in the website with the new theme. (Maybe instead of doing it by hand I can use a SQL trick.) This means that my URL will change because they include the page/post IDs.
What can I do to keep my site indexed in Google? I suppose I should create something somewhere to show Googlebot permanent redirections from the old URLS to the new ones. As Google Webmaster Tools guide says:
Once you have the listing of old URLs, decide where each one should redirect to. How you store this mapping depends on your servers and the site move. You might use a database, or configure some URL rewriting rules on your system for common redirect patterns.
But how can I do that?