This man favors SQL! That said, flexible schema is a two-edged sword with NoSQL solutions. The advantage of loose schema, in my experience, is NOT that you don't have a schema (or you will never be able to find anything), but that you can extend that schema very easily. Research.
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RT @a4w_m6h
Having a flexible schema is not generally a *feature*
https://twitter.com/a4w_m6h/status/1540464318742937601