Using bulk_update_mappings in SQLAlchemy to update multiple rows with different values

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The approach is correct in terms of usage. The only thing I would change is something like below

mappings = []
i = 0

for b, foo_x in session.query(Bar, Foo.x).join(Foo, Foo.id==Bar.foo_id):
    info = {'id':b.id, 'x': foo_x}
    mappings.append(info)
    i = i + 1
    if i % 10000 == 0:
        session.bulk_update_mappings(Bar, mappings)
        session.flush()
        session.commit()
        mappings[:] = []

session.bulk_update_mappings(Bar, mappings)

This will make sure you don’t have too much data hanging in memory and you don’t do a too big insert to the DB at a single time

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