Gillian Gunson

Gillian Gunson

Gillian Gunson

Database Infrastructure Engineer, GitHub


Gillian has been a database infrastructure engineer at GitHub for two years. Her focus has been on performance troubleshooting and observability. Previous employers include Okta, PalominoDB, Oracle and Disney. Gillian is based in Vancouver, BC, Canada.

All Sessions

MySQL Schema Migrations: Exploring the Options

Table migrations remain a pain point for MySQL DBAs. There are more options than ever for running migrations, with the later versions' in-place alters and new third-party tools (like gh-ost). But with the increase in tools and procedures it's been shown that there is no one-size-fits-all tool. Depending on the table size, available disk space, database traffic, server performance and SLAs, some migration methods make more sense than others.

In this tutorial we will discuss and demonstrate the different tools and methods and the best practices and scenarios for each.

Optional Lab Requirements:
- MacOS or Linux laptop (or VM)
- MySQL Sandbox, Percona Toolkit, gh-ost, sysbench
- MySQL 5.7 generic binary (for MySQL Sandbox)


Migration Concepts and Types
- Straight and in-place ALTER TABLE
- Alter on replicas, then promote
- pt-online-schema-change
- gh-ost

Caveats and Best Practices

- Test each of the migration types in a database cluster

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