django-materialized-views

Django Materialized Views

Use this skill when an expensive read query is reused often and can tolerate controlled staleness. Try query-plan, index, and ORM expression improvements first; materialized views add operational state.

Workflow

1. Confirm fit.

• The source query is expensive and stable.
• Consumers can accept stale data.
• Refresh cadence, ownership, and failure behavior are clear.
• PostgreSQL is the target database.

1. Design the materialized view.

• Define the SQL query and output columns.
• Add a unique column or unique column set if concurrent refresh is required.
• Add indexes for consumer queries against the view.

1. Integrate with Django.

• Create the view with RunSQL.
• Represent it as an unmanaged model with managed = False.
• Keep the unmanaged model fields aligned with the SQL output.
• Make writes impossible at the application boundary.

1. Implement refresh.

• Use REFRESH MATERIALIZED VIEW for simple refreshes.
• Use REFRESH MATERIALIZED VIEW CONCURRENTLY only when the view is already populated and has a qualifying unique index.
• Schedule refresh through a management command, task queue, or database job.

See [materialized-view-patterns.md](references/materialized-view-patterns.md) for migration, model, and refresh templates.

Safety Notes

• A materialized view returns stored data; it is not automatically current.
• Concurrent refresh avoids locking out reads but has prerequisites and still allows only one refresh at a time per view.
• Refreshing a large view can be a major database workload. Measure it separately from reads.

Verification

Validate the SQL against source tables, test the unmanaged model reads, prove refresh behavior, and measure read latency before/after.