I use Post Type Switcher to switch some of my blog post type from ‘post’ to ‘docs’ ( a custom post type), thus the URL is changed from /blog/* to /docs/*. I note that the original post at /blog/* ( eg: /blog/someinfo) is automatically (301) redirect to /docs/* ( eg: from /blog/someinfo to /docs/someinfo).

Changing the post type from ‘post’ to ‘page’ also has the same effect.

I thought that this is well explained by the WordPress creates redirect from old URL after changing slug question. So I use SELECT * FROM wp_postmeta where meta_key = "_wp_old_slug" to confirm that the redirection is indeed stored there. But to my huge surprise, I can’t find anything that has anything to do with the above redirection.

( If on the other hand, I just change the slug manually and not changing the Post Type, like changing the url from /blog/someinfo to /blog/someinfo-2, then I would see something at meta_value column, and hence I can rest assure that the redirection is real and permanent).

This creates a confusion for me. Where the redirection information is stored? Is the redirection permanent if I change Post Type? ( ie: /blog/someinfo will always be 301 redirect to /docs/someinfo)