Large Hadron Migrator
A Ruby gem for performing online MySQL schema migrations without locking tables, enabling agile database evolution at scale.
What is Large Hadron Migrator?
Large Hadron Migrator (Lhm) is a Ruby gem that enables online MySQL schema migrations without locking tables, allowing databases to evolve while remaining fully operational. It solves the problem of prolonged downtime when altering large tables by using a copy table and triggers to synchronize data changes during migration. This is particularly valuable for applications with tables containing millions of records where traditional ALTER TABLE operations would cause significant disruption.
Rails developers and database administrators working with large MySQL databases who need to perform schema changes without causing downtime. It is especially relevant for teams managing high-traffic applications where availability is critical.
Developers choose Lhm because it provides a robust, trigger-based solution for zero-downtime migrations that integrates seamlessly with ActiveRecord. Unlike some alternatives, it does not require an indexed updated_at column and offers flexible throttling and filtering options to handle large datasets safely and efficiently.
Overview
Online MySQL schema migrations
Use Cases
Best For
- Performing schema changes on large MySQL tables without downtime
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