应用引擎事务

Question

I have to add to a PropertyList a value for 50 entities. I have to make sure that no other code changes the PropertyList in the same time for particular entity. Is it better to have one big transaction changing all 50 entities or 50 small ones changing only one entity?

Answer 1

If you need exactly what your post says (updates to many entities, and transaction safety only on each entity), then you can use many small transactions.

If you must guarantee that none of the many entities is changed during this period, you should use one transaction, with all of your entities in the same entity group. Beware that the recommended update limit to entity groups is once per second. If you really have to update 50 entities transactionally, and you cannot for some reason put them into the same entity group, you should consider reorganizing your data.

Answer 2

this requirements most likely implies that you might want to reconsider your design.

currently you are solving the 'how to implement this' question.

perhaps you want to share your original problem so there can be a better solution to the question of 'this is how it should work'

looking forward.

-J