id	summary	reporter	owner	description	type	status	component	version	severity	resolution	keywords	cc	stage	has_patch	needs_docs	needs_tests	needs_better_patch	easy	ui_ux
30382	force_insert flag is not passed when saving parents on inherited models.	Phill Tornroth	Akash Kumar Sen	"We're using non-abstract model inheritance (table per model class) and issuing our own primary keys. When saving we pass force_insert=True to prevent the extra UPDATE statement that precedes the INSERT. The force_insert flag is respected on the child table but not on the parent. So given:

{{{
class ParentModel(models.Model):
    id = models.BigIntegerField(primary_key=True)

class ChildModel(ParentModel):
    pass

ChildModel(id=1).save(force_insert=True)
}}}

We'll see queries:

1. UPDATE app_parentmodel  (no rows affected)
2. INSERT app_parentmodel
3. INSERT app_childmodel

This is because Model.save_base doesn't pass force_insert along to Model._save_parents, and onto Model._save_table. Doing so would prevent the extra UPDATE and respect the spirit of the force_insert feature. This is a change I've made locally and seems to work / is pretty straightforward. I'm curious though if there's intent behind not carrying the force_insert functionality through for parents. I couldn't find any discussion on the topic.

For context about why this is particularly problematic in our case -- we're using MySQL w/ Innodb and Innodb will take out different exclusive locks for the UPDATE and INSERT in question -- so if you're creating new ChildModel instances in parallel you can get deadlocks when multiple threads issue query #1 and then need a lock with insert intention in order to get #2.
"	Bug	closed	Database layer (models, ORM)	dev	Normal	fixed			Ready for checkin	1	0	0	0	0	0