How do application updates exactly work?

Discussion in 'Mac Apps and Mac App Store' started by Hypnosis, Aug 1, 2015.

  1. Hypnosis macrumors member

    Jun 16, 2015
    New mac user here. I just wanted some clarification on what updates exactly do (storage wise). Do they replace and update existing files, or do they add onto the existing files? Frankly put, if I have an application that uses 1.5GB and there's an update available that is 800MB, will the application be 2.3GB after updating?
  2. chrfr macrumors 604

    Jul 11, 2009
    It's impossible to answer with certainty. Some updates will be large, but will replace existing resources in the application, while other updates may add new files that increase the application size.
  3. Hypnosis thread starter macrumors member

    Jun 16, 2015
    I was under the impression that this would be the case. I'm assuming majority of the iOS updates are the latter?
  4. Gav2k macrumors G3


    Jul 24, 2009
    Actually these days a lot of iOS apps are delta updates
  5. chrfr macrumors 604

    Jul 11, 2009
    Again, the same factors apply for iOS too. Both OS X and iOS use delta updates for applications.
  6. Starfia macrumors 6502


    Apr 11, 2011
    Applications are a collection of files delivered as a bundle. In OS X, you can go into your Applications folder, right-click on anything, choose "Show Package Contents" and actually see the files. They usually include some code files (the actual programming), images used in the applications interface, sounds, fonts, or whatever else.

    When a developer updates an application and you install the update on your computer, you're essentially replacing the entire bundle with the new version of the bundle. The new version might mean a simple bug fix (like, a slight change in one of the programming files) or a dramatic increase in files (like the addition of 100 new stock photographs). In any case, the total size of the application on your hard disk after the update is complete should equal the total size of only the newest version of the bundle. (As Gav2k mentioned, the system is capable of doing some clever things like noticing only which portions of the app have actually changed, and only using the bandwidth necessary to download those when you install an update.)

    It's tough to guess whether "most" of application updates involve added resources – I'd guess not, since so many updates are quick maintenance updates. You can probably infer about this by reading the description of the latest version for that app (e.g. "this update contains several bug fixes").

    I think you might be asking how that size is described when you're inspecting it in the App Store, and that I'm not sure about.

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