Google reduces size of Android app updates by 65 percent


Google Inc. announced on Thursday that it’s rolling out a new method for application updates via its Play Store that slashes data usage. But there is a downside.

The new method, called file-by-file patching, shrinks the size of app updates by 65 percent on average. However, it makes them about twice as slow to download. File-by-file patching is designed to reduce the amount of data to be downloaded to an absolute minimum, Google Play software engineer Andrew Hayden said in the company’s Android Developers blog.

Google said that in the last year, Android users had downloaded and installed a combined 65 billion apps from the Play Store. The problem is that modern apps are getting bigger and bigger, and developers are pushing app updates more frequently than ever before to accommodate new functions or security patches. But while many users appreciate the updates, few will deny that they’re becoming more and more of a data hog.

So Google’s file-by-file update method aims to minimize the amount of data that needs to be downloaded during updates. Back in the day, updating an app basically meant downloading an entirely new version of that app, even if the updates were relatively minimal. Google has worked to improve this in recent years, and these days users need to download onlly the parts of the app that have actually been updated, rather than the entire app.

Google reckons that file-by-file patching can lead to downloads that are 90 percent smaller than the full app itself, in some cases. The new method builds on changes Google announced earlier this year that also reduced the size of application updates. Back then, Google said it was using an algorithm to identify the changes made to an app, so only they would be applied. With file-by-file updates, Google Play first sends a very small patch that identifies the differences between the current and latest version of the app, before applying these updates.

The differences can be quite stark. For example, the most recent file-by-file patch size for Google Maps was 9.6 megabytes, compared to 13.4 MB when using the older method. Meanwhile, the latest Netflix update was 1.2 MB using the file-by-file patching method, compared with 7.7 MB before.

“The savings, compared to our previous approach, add up to 6 petabytes of user data saved per day,” Hayden said.

The only downside is that Google’s new method involves downloading lots of compressed data packaged in APK files, which then needs to be decompressed before it can be applied to the update. Once installed, this data is recompressed in a way that makes the updated app identical to the latest version on the Google Play store. These extra operations use a lot more processing power, which is why the actual updates take about twice as long, even though much less data is downloaded.

Because of the extended time it takes to download updates using the new method, Google will use it only for patches delivered as auto-updates, which usually occur in the background when the device is not being used.

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