_prime_post_caches in wordpress

These bits of caching are generally considered inadvisable to be messed with. If I remember right you can somewhat control the behavior by query arguments and wrapping related code in wp_suspend_cache_addition() calls.

From look through the source it doesn’t seem to be meant to carry custom logic. If you would like similar behavior for your custom data from non–native table you will likely have to implement caching logic for it yourself.