There was a time when updating an app required downloading a whole new version of that app, even if you already had parts of it. These days, however, updating an app really only requires downloading, well, the parts that are different. Google has been figuring out ways to reduce update sizes over the past four years or so and on Tuesday, announced it devised a way to reduce app updates by 65 percent.
File-by-file patching basically works by comparing new and old archives. Google goes through these to identify the changes, applies the changes, then checks to ensure that the patched app matches the updated version on the Google Play Store.
There is a downside to this method — it takes longer for your phone to process and that is why Google is not implementing the change for all apps just yet — for now, only auto-updates that take place in the background will use the new update method. […]