There's a difference between storing every single tap and just storing the latest position for each book and device pair. And the Kindle doesn't update whispersync every page tap anyways it syncs periodically so the Kindle is storing that tap info and sending it all so it's not like this is just a factor of logging the data it gets sent for updating page position. [0]
[0] I think Kindle on Android is the worst for this. Sometimes I don't get the position synced to my Kindle even 30min+ after leaving the Kindle app. Seems like the way to guarantee the server gets updated is to either exit the app or to return to the library.
Regardless, I fail to see how storing each update is more invasive than just storing the last update when the same number of requests are sent to Amazon.
The whole history builds up a picture of your habits and reading times where only storing the last gives just that the last time you read the book. Think about the difference between storing the last place you were vs everywhere you've been. Individual data points may be innocuous where a collection of the same data points isn't.
I'm really not being difficult. If you've logged the data there is no difference - for one, most of these db systems are write only. Even the ones that aren't probably have a transaction logs. Plus it will be recorded in countless other places along the way.
Slightly off topic: how do you know the DB is write only?? I've been looking for talks about the Kindle back end and haven't found any. I'd love to read about it, it appears to have solved some interesting problems!
Then perhaps you simply missed the point that was being made, which was that it's _possible_ to provide the features that Amazon promotes _without_ logging that much information on an ongoing and permanent basis.
