Develop I/O Client

[jaehyeon-kim]

The sql pyio connector should have a composite transform that executes a sql query in one or more partitions and outputs the results

Acceptance Criteria

• Create two DoFns
  • GenerateQueryFn generates a sql query into partitions
  • ProcessQueryFn executes partitioned queries as a splittable DoFn
• Create a composite transform that links the DoFns
  • It should be triggered at the beginning
  • Note to Reshuffle() so that each query is executed separately by preventing fusion