Looker joins with no declared relationship

This rule flags every join in an explore that does not declare relationship:. A refinement that adds it counts. Joins inherited from an explore that was not supplied cannot be seen, so they are not counted.

Looker assumes many_to_one when a join does not say. If the join is really one-to-many, Looker does not know the rows fan out. Measures from the base view can then be counted once per joined row.

Declare the relationship on every Looker join. Declare relationship: on each join as a decision rather than a default: many_to_one, one_to_many, one_to_one or many_to_many.

Before:

explore: orders {
  join: order_items {
    sql_on: ${orders.order_id} = ${order_items.order_id} ;;
  }
}

After:

explore: orders {
  join: order_items {
    relationship: one_to_many
    sql_on: ${orders.order_id} = ${order_items.order_id} ;;
  }
}

Very little. Where many_to_one is genuinely right the default does no harm today, but nobody can tell a decision from an oversight. Write it down; it is one line.

The .lkml files alone.