I'm about to rollout a product that could potentially need hundreds of connected EE sites. What is the limits to MSM? I can easily see a few hundred sites but it could be as big as a few thousand.

I have an EE site that has a large number of customizable features based on field types allowing the features to be activated. I would duplicate the site for every new install and customize it based on a specific brand. One instance will be for a large number of business franchises that need their own sites for local SEO purposes as well as offerings.

How can I utilize the EE MSM and not get limited by the database size, columns, etc...?

1 Answer 1



The theortical max limit on custom fields (which expands the channel_data table horizontally, not vertically) is the maximum number of columns divided by 2 (in EE 2, at least, it uses to columns per custom field) in a MyISAM table.


This is your real issue. Everything else basically expands vertically, so the column limit isn't an issue. I would say you can safely get to around 500 to 750 custom fields before hitting the limit, possibly 1000. The issues isn't how many sites (and you'll be paying for licenses for all of them), but how many custom fields. If your limit works out to 750 columns, and each site has 20 fields, your only looking at about 37~38 sites before hitting the wall.

Edit as a side note, I've always found it an unfortunate choice for EllisLab to not expand channel_data in it's own new table for new sites; InnoDB, for example, has a limit of 4 billion tables in a schema, and 1000 columns in a table. Which one makes more sense to take advantage of?

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