eltgroups

Overview ¶

Grouped ELT DAG: four groups — extract, transform, load, report — where each group fans out into parallel steps, the next group runs only after the previous group (declared once with After), and a step may depend on a sibling in its own group.

go run ./examples/eltgroups        # run the pipeline, print the groups
go run ./examples/eltgroups -out . # also write dag.json and dag.svg

The DAG view draws group boxes and group-to-group edges; the cross-group dependencies are not repeated on every member step:

EXTRACT ──► TRANSFORM ──► LOAD ──► REPORT
customers   customers ─┐  customers  dashboard ─┐
orders      orders ────┤  orders     metrics   ─┼─► send_alert
products    products   │  products   └──────────┘
                       └─ transform_customers → transform_orders

The ELT idiom: one task per stage, each deriving its table from StepFromContext(ctx).Step. Task names are process-unique, so registering a different closure per table under one name would silently keep the last one.