What exactly happens when apps update?

[AC Question]

what exactly happens when apps update

space is limited on my galaxy s4 I would like to know why it looks like when you up date an app it appears that not just the improvements but the entire app multi megabytes in size seems to get re downloaded. is that what happens or is something else going on? to check the size of the update while on my play account I tap on read more scroll all the way down to see the size of the app. that size seems to match the size that appears when I hit update any help with this is greatly appreciated thank you

 

[ruggedhunter]

Re: what exactly happens when apps update

Yes, when an app updates, you're downloading an entire new version of the full .apk file and it replaces the existing one already installed on your phone.

 

[Venkatramanan Ramasubramanian]

While updating an app, Android OS will keep the App data folder safely and only the remove the old version's Apk file. Then install the newer version's Apk file. But, While you uninstall the app, the App data, and the App's Apk file will be deleted from the mobile.

Android OS and Play store require developers to provide the whole new Apk for the update. Developers can't add features by publishing an extension kind of file to the old Apk.