Transactions are used for dry runs, even though they have been disabled

In the Resource class I fount the following line in the import_data method:

using_transactions = (use_transactions or dry_run) and supports_transactions

Now why does it use transactions for dry runs whenever transactions are supported, even though I have opted to disable transactions completely?

I have some pretty big imports (200k+ objects) that take a really long time with transactions. Is there a deeper reason why the line does not just read the following?:

using_transactions = use_transactions and supports_transactions

[beruic]

@bmihelac can you reopen this one?

[clint74]

It worked for me. The whole process was about 40 minutes before change, now 5 minutes. https://gist.github.com/clint74/bd74025e799bf7101a5471b08ecd1567

Dry run and no transactions combo makes save_m2m no-op:

https://github.com/django-import-export/django-import-export/blob/54232db4a511cc5f0b085c6bb192c3619f27e452/import_export/resources.py#L345-L359

Surely as you noticed this currently never happens as dry_run is always wrapped in transaction.

I am thinking about refactoring using_transactions = ... line so it retain current behaviour but can be changed to not use transactions in dry run as well.

using_transactions = supports_transactions and (
    use_transactions or
    (dry_run and self.use_transactions_in_dry_run())
)

Thoughts?