Not a week goes by without our smartphones and tablets tell us we have apps that require an update. And these updates are never small, typically requiring 10-20MB each. When your phone contract has a strict data limit in place, that's not great, but Google is set to drastically reduce the amount of data downloaded during an Android app update thanks to an intelligent new method of patching.
Android apps are delivered in the form of an APK file. This is simply a compressed archive much like a ZIP file. The compression reduces the size of the download, but it is by no means perfect. The process of compressing the data changes the whole structure of the APK, meaning it's impossible to tell which parts of it have changed compared to the existing installed version. So even if just a single line of text has been tweaked, the APK containing the change can be almost as large as the original app download.
Google is set to fix this problem with file-by-file patching. It works by uncompressing the existing APK and the newly patched APK and comparing the contents to identify what exactly has changed. The changed data is then used to form a much smaller patch APK, which is then compressed and downloaded to your device.
As the table above shows, using file-by-file patching cuts the amount of data downloaded significantly. On average the saving is around 65 percent, but can be as high as 90 percent. Google claims six petabytes of data will be saved per day compared to the old method of updating apps.
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There is one trade off to this new method of patching: more processing is required on the target device in order to apply the patch. Google calculates that any device released from 2015 onwards will spend an extra second per megabyte processing the patch. Older devices will take longer.
Extra processing time means batteries drain more quickly, but we're only talking a few seconds per app here. I'm sure most smartphone and tablet owners won't mind that if it means app updates drop in size by 65 percent. The extra processing time will also continue to get smaller as we adopt new, more powerful and power efficient devices.
Google is cautiously rolling out this new method of patching. For now, it will be limited to app updates that occur automatically and in the background on devices. As it saves so much data, though, I doubt it will take long before this becomes the preferred method of patching all Android apps.