Mike, may I suggest this as an enhancement: If SQLA is creating a table with an 
Enum column, and if there's already an Enum with the specified name, it should 
spit out an error if the list of values for the existing and requested Enums 
don't match?

Maybe, though would that same logic extend to other constructs ?  Such as, if 
you had a Table, and you said metadata.create_all(), that particular Table 
already exists.  Should SQLAlchemy go out, reflect that table and compare all 
the column names to the Table you have and report an error ?    Seems like the 
same thing.

Alembic does this comparison, but it's more of a helper to write migrations 
rather than a consistency checker, since we can't reliably match everything 
about the database to what's defined in Python.

Yeah you're right, it's essentially the same thing. Personally, I was a bit 
surprised when I discovered that SQLAlchemy just ignores already-created 
tables, even the model is different to the preexisting table. However, it also 
means that if you have a script that imports and creates all models, you can 
use it no matter whether you have changed/added a single model or all of them, 
so there's that.

I guess I just got a bit tripped up because my SQL/database knowledge perhaps 
isn't what it should be, so I didn't really understand how an enum would be 
implemented and that simply trying to redefine it would cause problems. SQLA 
makes things so easy, it can be easy to get complacent and assume that 
everything will just work, without thinking about the database!



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