Some Android app updates could cut their file sizes by 65 percent or more

As any Android smartphone owner knows, updates from the Google Play Store can come quite frequently for many popular apps. They can also use up data if updates are conducted on a cellular network. Today, Google announced a new approach for Android app downloads. The good news is this method could solve the problem of using a ton of data for such updates.

In a blog post, Google describes the new approach, which it calls File-by-File patching. In the old days, Android apps were updated by downloading the app’s entire APK file. In 2016, the company began using the bsdiff algorithm to cut app file size updates by 47 percent. File-by-File patching can go even further, reducing app updates by an average of 65 percent. In fact, some app updates could be cut down by as much as 90 percent with this method.

Normally, an APK file is compressed using a technology called Deflate, but Google says any change to the app’s original uncompressed content “can make the compressed output of deflate look completely different.” Google uses File-by-File patching to achieve its results by detecting the changes in the uncompressed data. Google says this allows apps to uncompress the data, then apply a patch, and then recompress that data back to the same number of bytes that were originally uploaded by the publisher.

The good news is that the actual file size for each update can go down, but the bad news is that it does take more time to apply that same patch on a smartphone, due to the extra processor power that is needed. Google says it will apply the new File-by-File patching method to Android apps that take place in the background. If you plug in your smartphone at night, your apps will likely use this method to auto-update themselves while you are sleeping.