How does this skill prevent database downtime during deployments?

This skill prevents the table-level locks and service outages often caused by standard Django migrations on high-traffic PostgreSQL databases by enforcing safe patterns like concurrent indexing and mandatory timeouts.

Can I use this skill with databases other than PostgreSQL?

The skill is specifically optimized for Django environments using PostgreSQL; it is not compatible with MySQL, SQLite, or other database backends due to its reliance on Postgres-specific locking logic.

What exactly is included in the toolkit?

You will receive a specialized toolkit including the `TimeoutAwareMigration` base class, custom concurrent operation overrides, and a dedicated linter to identify production hazards.

Does this skill help with complex breaking changes like renaming or deleting fields?

The skill guides you through the 'expand-contract' pattern, which involves a multi-release process to ensure that your application code remains compatible with the database state at every step of the migration.

Does this require changing how I run migrations in my CI/CD pipeline?

Yes, it integrates directly with standard Django migration commands, replacing risky default operations with safety-first alternatives like `AddIndexConcurrentlyWithRetry`.

Why should I use this skill instead of just asking a general AI for migration help?

The skill identifies 'hidden' risks that generic AI prompts often miss, such as the 'one concurrent operation per file' rule and the necessity of two-step validation for foreign keys.

Zero-Downtime Django Migrations

Example session with this skill installed

Add a NOT NULL status column with a default to our 80M-row orders table and index it. How do we ship this without downtime?

Read your context and instructions
Compiled the zero-downtime django migrations

Summary

Ship it in three releases. A single AddField(null=False, default=...) plus a normal AddIndex would take heavy locks on a hot table. Example output; names are illustrative.

Plan

Release	Migration	Why it is safe
1. Expand	`AddField(status, null=True)` with no default	Metadata-only, no table rewrite
1. Expand	App code starts writing `status` on every save	Old rows are still NULL, which is fine
2. Backfill	`RunPython` in batches of 5,000 ids, one transaction per batch	No long transaction, replicas keep up
2. Index	`AddIndexConcurrently` in a non-atomic migration	Builds without blocking writes
3. Contract	`CHECK (status IS NOT NULL) NOT VALID`, then `VALIDATE CONSTRAINT`, then `SET NOT NULL`	Validation takes a weak lock, SET NOT NULL skips the scan

Guard rails on every migration

class Migration(TimeoutAwareMigration):
    lock_timeout = timedelta(seconds=15)
    statement_timeout = timedelta(seconds=20)

Next steps

Run the migration linter (--fix) on the generated files.
Deploy release 1 and wait for old pods to drain before release 2.
Confirm zero NULLs before adding the constraint in release 3.

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About this skill

Never take production down with a migration again

Migrations run before the new code rolls out, so for a few minutes old code talks to the new schema. This skill teaches your agent to write Django and PostgreSQL migrations that survive that window: no long locks, no table rewrites, nothing the running code still needs gets removed.

How it helps

No surprise outages. Every migration gets a lock timeout and a statement timeout, so it fails fast instead of blocking traffic.
Safe indexes and constraints. Concurrent index creation, and NOT VALID then VALIDATE for new constraints.
Safe multi-release changes. Expand, migrate, contract: split risky changes across releases so old and new code both keep working.
Safe backfills. Batched data migrations that don't hold a transaction open on a hot table.
Fewer review debates. A per-operation lock reference and checklists tell reviewers what is safe and what is not.

What's inside

A short SKILL.md with the two golden rules and the migration toolkit pattern, plus 4 reference guides: Postgres locks, indexes, columns/keys/constraints, and data backfills and deployment.

Use it when

Adding or changing columns, indexes, constraints or foreign keys, writing RunPython/RunSQL backfills, reviewing makemigrations output, or setting up migration safety in a new Django service.

How to use

Skills on Agensi run inside your AI agent. Copy the prompt, paste it into your agent, and it connects to Agensi and installs this skill for you. If a payment is needed, your agent shows it to you first.

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Zero-Downtime Django Migrations