I have done EAV on top of MySQL, and it is either complex and scales poorly or you have unsearchable blobs. It looks like they are doing the blob route. ot

I have done EAV on top of MySQL, and it is either complex and scales poorly or you have unsearchable blobs. It looks like they are doing the blob route. other properties are serialized in a binary blob EAV on top of SQL is re-inventing the wheel. Likely they would be much better of with MongoDB or some other DB that actually has some amount of support for EAV.