before_commit_from_insert actually issues UPDATE command following the INSERT command

[mmangione]

It would seem to me if the before_commit_from_insert command is used we should be operating on an object pre-commit, then committing it. So, that would be equivalent to operating on the object, making updates, the inserting the updated object through the INSERT command. That is not what is happening. The INSERT command is putting the object in the database and then an UPDATE command is issued with the updated content from the before_commit_from_insert command.

[mmangione]

We were inserting about 25M records in 25,000 record increments. It was taking 630s/batch - so our process was taking days. I then switched to a custom method that simply operates on the object prior to a standard commit and it was taking 21s/batch. So, it was a pretty stark difference.