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Comment by bavell | Hacker News Reader

What are the pros/cons of using entirely different (siloed) databases with uniform permissions instead of a single database supporting granular permissions?

Off the top of my head, I'd say security might be improved but ease of use may suffer. Interested in hearing other's thoughts on the matter.

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The cons are inumerable. We've been down that road before and the whole world of business intelligence and enterprise data warehousing came out of it. When every functional unit has their own db, how do you answer questions of the business as a whole? How do you deal with data that multiple functional areas need? On top of that, managing a lot of small silos requires a lot more work and resources then the alternative.

Eventually you're going to want to bring that data all together and now you have to have data architects and engineers developing etl solutions and then your resulting data warehouse is going to be that singular database you were trying to avoid from the start, with all the overhead of building it and maintaining it on top of all the maintenance of the source silos.

See https://en.wikipedia.org/wiki/Data_warehouse

One thing to note is that the singular database used for answering business questions is often not customer facing, and thus does not have as strong reliability guarantees (In my experience). Most of the business analytics happens asynchronously (etl pipelines everywhere).

I'm not sure how to avoid this. The need to answer business question favors a single, queryable DB whereas the need to keep applications siloed and abstracted away favors multiple application data stores.

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