Whenever I read something like "ISPs store your data" or "ISPs delete your data after 6 months" or anything like that, I imagine data to be the following things:
(1) At what time I accessed the Internet, got what IP address (in case of dynamic IPs) and accessed what website with it.
(2) How long I remained on that website.
(3) And of course, regarding the "I" in (1), they also know everything about me, including my name, phone number, actual address etc.. (i.e., the subscriber's details)
So, when the police subpoena ISPs to resolve an IP address at a particular time on a particular day to a real person (the subscriber) and their details, they do have all the records regarding who had what IP and when? This is how police find criminals, right?
What happens when ISPs delete logs (as most ISPs do due to financial constraints), and police approach them asking to resolve an IP address at a particular time on a particular day to a real person and their details (contact, address etc..)?
Does "deleting logs" mean deleting the record of which subscriber was assigned what dynamic IP address and when? Or ISPs never delete data about who had what IP and when, but just delete what they had accessed and for how long?
I suppose that merely keeping records forever of who had which IP and when is cheap (compare with keeping a record of all the videos someone has ever watched), and beneficial to law enforcement.
Related questions that I checked:
The answers did not specifically address whether "deleting" means deleting the record of who had which IP and when (which is a cheap but extremely useful thing to keep indefinitely).