Does the entity framework preserve ordering when it does inserts into the database?

Question

We plan on using identity columns in our sql server database. Currently we are using guids to generate unique ids, but it turns out that the ordering is relevant so we consider switching to identity columsn.

Since ordering is relevant we want to make sure that the order in which we add objects to the entity context is also the order in which they are inserted into the database. This is relevant since sql server will be generating values for the identity column.

Is this guaranteed by the entity framework? If not, what is an efficient solution to generating your own unique integer ids for a database that is being updated from different processes.

Answer 1

I wouldn't rely on the insert order as the order of your records returned. Sure, it'll work most of the time, but what if you ever need to insert a row somewhere? I'd say your best bet is to add an ordinal column and actively generate ordinals for each row as you'd like them to be returned.

Answer 2

I am just guessing here (although it should be pretty easy to test), but I don't think EF can guarantee the order. I am pretty sure that the internal structure is based on an IEnumerable type, probably a List, which are just enumerated during insert, and enumeration is as far as I know not guaranteed to be in the same order every time.

I would instead add a dedicated "sort order" column to your database table and take it form there.