# github/gh-ost

GitHub's Online Schema-migration Tool for MySQL

Repository: https://github.com/github/gh-ost
Canonical: https://ross.abutalabs.com/products/gh-ost
Language: Go
License: MIT
License Family: permissive
Topics: mysql, schema-migrations
Last push: 2026-08-26T12:22:06+00:00

## Health v2 (maintenance only)
Score: 95/100 (v2, computed 2026-09-02T17:46:02.011165+00:00)
- activity 99, release rhythm 86, longevity 100
- inputs: {"age_days": 3817, "days_push": 7, "days_rel": 16, "gap_med": 62.5, "n_releases_24m": 5}
- flags: none
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 13540, forks 1416 (observed 2026-08-28T04:11:03.490656+00:00)

## What it is
gh-ost is GitHub's triggerless online schema migration tool for MySQL. It copies tables to a ghost table while streaming binary log changes asynchronously, enabling pausable, throttled, and auditable migrations with minimal load on the master.

## Use cases
- run online schema migrations on mysql without locking tables
- add or drop columns on large mysql tables with zero downtime
- migrate a mysql table schema without triggers
- throttle or pause a live table migration on a busy master
- test schema migrations safely on a replica before running on production
- change table indexes on high-traffic mysql databases

## When to choose
- you need zero-downtime schema changes on large, busy MySQL tables
- you want a migration tool that avoids triggers and their overhead
- you need fine-grained control: pause, throttle, and dynamically reconfigure migrations
- you want to validate migrations on replicas before applying them to masters

## When to avoid
- you use a database other than MySQL
- your tables are small enough that a simple ALTER TABLE is acceptable
- you cannot access the binary log stream or replicas
- you need migrations for non-table objects like stored procedures

## Facets
- artifact type: cli-tool
- maturity: active
- function: database, deployment, cli
- domain: databases, developer-tools
- platform: go, cli
- tags: mysql, schema-migration, online-schema-change, triggerless, binlog, database-migrations, devops, linux, macos

## Member repositories
- github/gh-ost (main) score 95

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:11:03.490656+00:00.
- Health v2: computed from the inputs above; adoption is never an input.
- Inferred fields (summary, facets, guidance): AI-extracted, prompt v1, taxonomy v1, on 2026-08-29T17:13:13.874936+00:00, confidence not recorded.
  - readme: https://github.com/github/gh-ost (fetched 2026-08-28T04:11:03.490656+00:00, sha 66b2f3343714)
- Data as of 2026-08-30T08:39:29.467469+00:00.