Florian Apolloner bc7dd8490b Fixed #21171 -- Avoided starting a transaction when a single (or atomic queries) are executed. ... Checked the following locations: * Model.save(): If there are parents involved, take the safe way and use transactions since this should be an all or nothing operation. If the model has no parents: * Signals are executed before and after the previous existing transaction -- they were never been part of the transaction. * if `force_insert` is set then only one query is executed -> atomic by definition and no transaction needed. * same applies to `force_update`. * If a primary key is set and no `force_*` is set Django will try an UPDATE and if that returns zero rows it tries an INSERT. The first case is completly save (single query). In the second case a transaction should not produce different results since the update query is basically a no-op then (might miss something though). * QuerySet.update(): no signals issued, single query -> no transaction needed. * Model/Collector.delete(): This one is fun due to the fact that is does many things at once. Most importantly though: It does send signals as part of the transaction, so for maximum backwards compatibility we need to be conservative. To ensure maximum compatibility the transaction here is removed only if the following holds true: * A single instance is being deleted. * There are no signal handlers attached to that instance. * There are no deletions/updates to cascade. * There are no parents which also need deletion.		2018-10-17 12:19:02 +02:00
..
__init__.py
models.py
tests.py