Database Migrations FAQs

Question 1

How do I add an index to a large production table without downtime?

Accepted Answer

This skill recommends using 'CREATE INDEX CONCURRENTLY' in PostgreSQL, which allows the index to be built without blocking writes, though it must be handled outside of standard transaction blocks.

Question 2

Why should I avoid adding a NOT NULL column to an existing table?

Accepted Answer

Adding a NOT NULL constraint without a default on an existing table often requires a full table rewrite and long-running lock. It is safer to add the column as nullable, backfill the data, and then add the constraint.

Question 3

Does this skill support modern ORMs like Prisma and Drizzle?

Accepted Answer

Yes, it includes specific workflows and schema examples for Prisma, Drizzle, Django, and golang-migrate to ensure best practices across different development ecosystems.

Question 4

What is the expand-contract pattern for migrations?

Accepted Answer

It is a three-phase strategy (expand, migrate, contract) that allows you to change database schemas without application downtime by supporting both old and new versions of a column or table simultaneously during a transition period.

Database Migrations

Key Features

Use Cases

Database Migrations

Key Features

Use Cases