When I add multiple unique_together tuples in my django model, the PostgreSQL DB mapping appears wrong (also according to a previous SO answer on the subject). An example follows.
This is my migration:
migrations.CreateModel(
name='FinancialConcept',
fields=[
('id', models.AutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
('taxonomy', models.CharField(max_length=128)),
('name', models.CharField(max_length=256)),
('xbrl_element', models.CharField(max_length=256)),
('parent', models.ForeignKey(null=True, on_delete=django.db.models.deletion.SET_NULL, to='analysis.FinancialConcept')),
],
),
migrations.AlterUniqueTogether(
name='financialconcept',
unique_together=set([('taxonomy', 'name'), ('taxonomy', 'xbrl_element'), ('parent', 'xbrl_element')]),
),
....
which I expected would create three UNIQUE indexes, one for each pair. But instead, what the DB mapping ends up being is this:
Column | Type | Modifiers
--------------+------------------------+------------------------------ ------------------------------------------
id | integer | not null default nextval('analysis_financialconcept_id_seq'::regclass)
taxonomy | character varying(128) | not null
name | character varying(256) | not null
xbrl_element | character varying(256) | not null
parent_id | integer |
Indexes:
"analysis_financialconcept_pkey" PRIMARY KEY, btree (id)
"analysis_financialconcept_taxonomy_xbrl_element_d8b45254_uniq" UNIQUE CONSTRAINT, btree (taxonomy, xbrl_element)
"analysis_financialconcept_parent_id_51fc8021" btree (parent_id)
I.e, one of the UNIQUE indexes is right, but the other two are missing.
Any idea what is causing this?
