Databases under 200GB

For smaller environments that can tolerate a little downtime, use a simple pg_dump/pg_restore process. Here are the steps.

  1. Save the database structure:

    pg_dump \
       --format=plain \
       --no-owner \
       --schema-only \
       --file=schema.sql \
       --schema=target_schema \
       postgres://user:[email protected]:5432/db
    
  2. Connect to the Citus cluster using psql and create the schema:

    \i schema.sql
    
  3. Run your create_distributed_table and create_reference_table statements. If you get an error about foreign keys, it’s generally due to the order of operations. Drop foreign keys before distributing tables and then re-add them.

  4. Put the application into maintenance mode, and disable any other writes to the old database.

  5. Save the data from the old database to disk with pg_dump:

    pg_dump \
       --format=custom \
       --no-owner \
       --data-only \
       --file=data.dump \
       --schema=target_schema \
       postgres://user:[email protected]:5432/db
    
  6. Import into Citus using pg_restore:

    # remember to use connection details for Citus,
    # not the source database
    pg_restore  \
       --host=host \
       --dbname=dbname \
       --username=username \
       data.dump
    
    # it'll prompt you for the connection password
    
  7. Test application.

  8. Launch!