Multiple Client Versions

In some cases, different client versions may need different output schemas.

When schema changes are additive, old clients would just ignore the new tables and columns, and no special handling is required. However, in some cases, the schema changes may be more drastic and may need separate Sync Rules based on the client version.

To distinguish between client versions, we would pass in an additional client parameter from the client to the PowerSync instance. These parameters could be used to implement different logic based on the client version.

Example to use different table names based on the client's schema_version:

# Client passes in: "params": {"schema_version": <version>} 
  assets_v1:
    parameters: SELECT request.user_id() AS user_id
      WHERE request.parameters() ->> 'schema_version' = '1'
    data:
      - SELECT * FROM assets AS assets_v1 WHERE user_id = bucket.user_id
      
  assets_v2:
    parameters: SELECT request.user_id() AS user_id
      WHERE request.parameters() ->> 'schema_version' = '2'
    data:
      - SELECT * FROM assets AS assets_v2 WHERE user_id = bucket.user_id

Handle queries based on parameters set by the client with care. The client can send any value for these parameters so it's not a good place to do authorization. If the parameter must be authenticated, use parameters from the JWT instead. Read more: Security consideration