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
22125	Unnecessary creation of index for ManyToManyField	tbhtan3@…	Rodrigo Vieira	"Suppose I have the following model:
{{{
class Food(models.Model):
  restaurants = models.ManyToManyField(Restaurant)
}}}
The following table is created:
{{{
CREATE TABLE ""main_food_restaurants"" (
    ""id"" integer NOT NULL PRIMARY KEY,
    ""food_id"" integer NOT NULL,
    ""restaurant_id"" integer NOT NULL,
    UNIQUE (""food_id"", ""restaurant_id"")
)
}}}
and the indexes:
{{{
CREATE INDEX ""main_food_restaurants_0899c464"" ON ""main_food_restaurants"" (""food_id"");
CREATE INDEX ""main_food_restaurants_be4c8f84"" ON ""main_food_restaurants"" (""restaurant_id"");
}}}
Notice that  the single index on food_id is not needed due to the unique index `(food_id, restaurant_id)`.
"	Cleanup/optimization	assigned	Database layer (models, ORM)	dev	Normal		db-indexes	emorley@… Phil Krylov Dan LaManna	Accepted	1	0	0	1	0	0