schemadiff: in memory schema analysis, validation, normalization, diffing, and manipulation

schemadiff is a library within the Vitess project, which uses a programmatic approach to analyzing database schemas independently of a MySQL server. schemadiff powers Vitess' own internal schema management as well as the user facing Online DDL logic. In this session we take a deep dive into schemadiff's capabilities, and show how the community can use it to solve very common schema change and schema management tasks and problems. We discuss:

• Parsing.
• Per table and per database validations.
• Normalization.
• Diffing tables, diffing databases.
• Schema change conflicts and dependencies.
• Generating a successful sequential migration route.
• In-memory schema manipulation.
• Performance.
• Extras: INSTANT DDL, Online DDL support, constraint analysis.

schemadiff is part of Vitess, a CNCF project released under the Apache 2 license. We illustrate some real-world scenarios from PlanetScale's (main sponsors of the Vitess project) schema deployment system.