Technically, how would something like this architecturally be structured? Curious how they would sandbox the user data and still provide a SQL like interface.

Technically, how would something like this architecturally be structured? Curious how they would sandbox the user data and still provide a SQL like interface. I wrote something for Doctrine last year where I let my users query their own data using DQL. I had to write a TONNE of AST walkers to ensure that they weren't accessing entities they didn't have permissions to. Was a huge issue that I wish I didn't start :D (But one of those cool things when it was finished)