Hello,
While looking for a good way to implement a bulk update to numerous rows of
the same table, I came across this performance example
<https://github.com/zzzeek/sqlalchemy/blob/master/examples/performance/bulk_updates.py>
:
session = Session(bind=engine)
for chunk in range(0, n, 1000):
customers = session.query(Customer).\
filter(Customer.id.between(chunk, chunk + 1000)).all()
for customer in customers:
customer.description += "updated"
session.flush()
session.commit()
I noticed that the flush() happens with every iteration over the chunks,
instead of the end, right along with commit(). Why is that?
And is the above the recommended way of a bulk update, instead of e.g.
calling Table.update()
<http://docs.sqlalchemy.org/en/latest/core/metadata.html#sqlalchemy.schema.Table.update>
as recommended in this SO answer
<https://stackoverflow.com/questions/25694234/bulk-update-in-sqlalchemy-core-using-where#25720751>
?
Thank you!
Jens
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