Migrating an Existing App

Migrating an existing application to Citus sometimes requires adjusting the schema and queries for optimal performance. Citus extends PostgreSQL with distributed functionality, but it is not a drop-in replacement that scales out all workloads. A performant Citus cluster involves thinking about the data model, tooling, and choice of SQL features used.

The first steps are to optimize the existing database schema so that it can work efficiently across multiple computers.

• Identify Distribution Strategy
  • Pick distribution key
  • Identify types of tables
• Prepare Source Tables for Migration
  • Add distribution keys
  • Backfill newly created columns

Next, update application code and queries to deal with the schema changes.

• Prepare Application for Citus
  • Set up Development Citus Cluster
  • Add distribution key to queries
  • Enable Secure Connections
  • Check for cross-node traffic

After testing the changes in a development environment, the last step is to migrate production data to a Citus cluster and switch over the production app. We have techniques to minimize downtime for this step.

• Migrate Production Data
  • Small Database Migration
  • Big Database Migration