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
7170	Multi-table inheritance generates many UNIQUE indexes on MySQL	sylvaintersideral@…	nobody	"Creating the following very simple model :
{{{
class Interactable(models.Model):
  pass

class News(Interactable):
  title = models.CharField(max_length = 50)
  excerpt = models.CharField(max_length = 100)
  text = models.TextField()
}}}

And then synchronizing the database reveals that 2 unique indexes and
1 primary key refers to interactable_ptr_id in the news table :

- PRIMARY [[BR]]
- interactable_ptr_id (unique) [[BR]]
- files_news_interactable_ptr_id (unique) [[BR]]

The SQL transaction looks like this :
{{{
BEGIN;
CREATE TABLE `files_news` (
    `interactable_ptr_id` integer NOT NULL UNIQUE PRIMARY KEY,
    `title` varchar(50) NOT NULL,
    `excerpt` varchar(100) NOT NULL,
    `text` longtext NOT NULL
)
;
CREATE TABLE `files_interactable` (
    `id` integer AUTO_INCREMENT NOT NULL PRIMARY KEY
)
;
ALTER TABLE `files_news` ADD CONSTRAINT
interactable_ptr_id_refs_id_71833d78 FOREIGN KEY
(`interactable_ptr_id`) REFERENCES `files_interactable` (`id`);
CREATE UNIQUE INDEX `files_news_interactable_ptr_id` ON `files_news`
(`interactable_ptr_id`);
COMMIT;
}}}

I think there should be only ONE index (or maybe two ?), but not
three. Though I'm not sure about which one to keep : the primary key
is essential, but the reference to the parent table too, when using
InnoDB... but I think the last one is definitely useless."		closed	Database layer (models, ORM)	dev		fixed	qsrf-cleanup multi-table inheritance unique primary	gav@…	Unreviewed	0	0	0	0	0	0