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Again the assumption that no change in `schema_version` means that the observed schema stayed the same is not correct. One counter example is creating a temporary table. This doesn't increase the `schema_version` flag, but it allows you to shadow any existing table with whatever different structure you like. That's connection specific behavior, so you won't be able to observe that from other database connections. As soon as you allow users to execute arbitrary SQL (which you definitively want as you cannot reasonably provide a DSL for all supported SQL constructs) it's possible to break you assumption in that way.