Google makes app updates 65 percent smaller than original apk

Google has implemented a new technique in the Play Store that makes app updates on average up to 65 percent smaller than the original apk. With some apps, the updates are 90 percent smaller. It does take longer to perform an update.

Reducing app updates ensures that users get the latest version of an app faster and use less data. According to Google, this results in a decrease in data traffic of six petabytes per day.

The new saving works through file-by-file patching, with Google sending a patch to the user’s device describing the difference between the old and new version of the app. Then the app is extracted on the user’s device and the difference is applied. After that, the new file is compared with the original app in the Play Store.

Although the new method allows for smaller downloads, updating requires more processing power because the app has to be repackaged after the update has been performed. According to Google, repacking takes just over a second per megabyte using modern devices as of 2015.

When an update is halved in size, it takes on average twice as long to apply. That is why Google only applies the technology for the time being with automatic updates, which, according to the Android maker, are mainly performed at times when users are not using their device.

In July, Google already came up with a way to significantly reduce the update size of apps. At the time, it used the bsdiff algorithm, which made updates half the size of the original apk on average. The new file-by-file method complements that technique.

Percentages from original apk size