If use of Multi-DB reversible? Is it a bad idea for some?

I’m redoing my website and hope that it will be a very big site someday (using multisite). However, it’s not “big” yet. Should I use multi-db yet? Or should I wait? If I do use it and set it for lots of databases, what happens if I turn off the plugin? Is this a permanent type of change I’m making to the database structure? When should I and should I NOT use multi-db?


  • Kimberly
    • Champion of Loops

    Hi there and Thanks for using WPMUdev forums!

    You really shouldn’t bother with Multi-DB until after you have lots and lots and lots (and lots!) of sites.

    It’s used for optimizing what you have in place, not for preparing for a large site. As far as reversing, I am not sure. I would like to know myself, I will see if I can get the developer to comment here for us on that. :slight_smile:

    I would imagine that reversing would be incredibly difficult if not nearly impossible, but we will wait for the official word and maybe some extra advice on why Multi-DB is best to wait to use.



  • Barry
    • DEV MAN’s Mascot

    If you expect rapid growth (as in hundreds / thousand sites in a very short period of time) and continued growth at that pace, then it would be worth setting up multi-db at the beginning.

    If you expect a slower initial growth then don’t bother with it for now – though there will be a short period of time when you do finally move to multi-db when you will have to restrict write access to the db in order to maintain consistency when you do the transfer (should be less than 30 mins).

    Is this a permanent type of change I’m making to the database structure?

    Yes, you are moving from using a single database to using multiple ones, so it’s a huge change to the database structure. It can be reversed, but takes work and again you would have to restrict write access to the db when doing it to maintain consistency between the data you are in the process of transferring and the data that hasn’t been moved yet (depending on the number of databases you use it could be less than 30 mins, to an hour or so).

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