Google wants you to use as little data as possible to keep your Android apps updated to their latest versions. Android typically does this on your behalf by downloading updates for installed apps when you're on a Wi-Fi connection. If you're an update-a-holic, though, you can also allow Google Play to install updates whenever it wants—which might not be very fun for your monthly data quota.
"Google Play continues to grow rapidly, as Android users installed over 65 billion apps in the last year from the Google Play Store. We're also seeing developers move to update their apps more frequently to push great new content, patch security vulnerabilities, and iterate quickly on user feedback," reads a post on Google's Android Developers blog.
"However, many users are sensitive to the amount of data they use, especially if they are not on Wi-Fi. Google Play is investing in improvements to reduce the data that needs to be transferred for app installs and updates, while making data cost more transparent to users."
Google previously introduced what it calls "delta" updates in 2012, which allow Android owners to download portions of an app—only the bits that developers have updated—rather than the entirety of the app itself each time a new version hits. These "smart" updates can save a considerable amount of data for those updating their apps over their cellular connections, but it's not good enough for Google.
"For approximately 98% of app updates from the Play Store, only changes (deltas) to APK files are downloaded and merged with the existing files, reducing the size of updates. We recently rolled out a delta algorithm, bsdiff, that further reduces patches by up to 50% or more compared to the previous algorithm. Bsdiff is specifically targeted to produce more efficient deltas of native libraries by taking advantage of the specific ways in which compiled native code changes between versions. To be most effective, native libraries should be stored uncompressed (compression interferes with delta algorithms)," reads Google's blog post.
Google's tweak also applies to the the APK expansion files that developers are allowed to pack along with their apps. These files, which can be up to 2GB in size, can include things like HD graphics for mobile games or supplemental media files. With Google's new compression algorithms employed, the company claims that download sizes for these expansion files have decreased 12 percent for initial installs and 65 percent, on average, for expansion file updates.
"Alongside the improvements to reduce download size, we also made information displayed about data used and download sizes in the Play Store clearer. You can now see actual download sizes, not the APK file size, in the Play Store. If you already have an app, you will only see the update size. These changes are rolling out now," Google notes.