Hi there, The Postgres introspection backend's get_constraints function will only pull in constraints from the 'public' schema* (https://github.com/django/django/blob/stable/1.11.x/django/db/backends/postgresql/introspection.py#L186). This has the effect that calling get_constraints() for a database where the default schema is not named 'public' will return no constraints. This in turn means that database migrations which affect foreign keys will fail (because foreign key constraints are deleted and then recreated during a migration, but no foreign keys are found to delete, so keys with duplicate names are created, which postgres considers an error).
Because the name 'public' is hardcoded, this is not affected by search_path. I'm new to Django internals, so am wondering what is appropriate here and would appreciate opinions. Options as I see them: 1. Remove the constraint on 'public' in that function and just return all constraints. The introspection code already limits the list of constraints to a particular table. Database migration code assumes that it can remove and re-create foreign keys at will, so hiding keys from it based on schema seems like an invitation for further problems. But perhaps I'm missing something here. 2. Support specifying the default schema to the introspection code, via a mechanism similar to (or actually by using) psycopg2's search_path option. Then this schema name could be specified in the introspection query. 3. Don't change anything and require everyone to use the 'public' schema. 4. Something else. Any comments appreciated! Nicholas * Schemas: https://www.postgresql.org/docs/9.6/static/ddl-schemas.html . I find the use of the word "schema" here a bit confusing. Internally Postgres calls these "namespaces": https://www.postgresql.org/docs/9.6/static/catalog-pg-namespace.html -- You received this message because you are subscribed to the Google Groups "Django developers (Contributions to Django itself)" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at https://groups.google.com/group/django-developers. To view this discussion on the web visit https://groups.google.com/d/msgid/django-developers/41b6787b-845c-4df8-abb3-27d932616798%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
