Empty Mapping#

The empty mapping is a dummy mapping which produces and empty output but with a specified schema. This is mainly useful for mocking other mappings in tests.

Example#

mappings:
  empty_mapping:
    kind: empty
    columns:
      id: String
      temperature: Float
      wind_speed: Float

mappings:
  empty_mapping:
    kind: empty
    schema:
      kind: inline
      fields:
        - name: id
          type: string
        - name: amount
          type: double

Fields#

  • kind (mandatory) (type: string): empty

  • broadcast (optional) (type: boolean) (default: false): Hint for broadcasting the result of this mapping for map-side joins.

  • cache (optional) (type: string) (default: NONE): Cache mode for the results of this mapping. Supported values are

    • NONE

    • DISK_ONLY

    • MEMORY_ONLY

    • MEMORY_ONLY_SER

    • MEMORY_AND_DISK

    • MEMORY_AND_DISK_SER

  • columns (optional) (type: map:string): Specifies the list of column names (key) with their type (value)

  • schema (optional) (type: schema): As an alternative of specifying a list of columns you can also directly specify a schema.

  • filter (optional) (type: string) (default: empty): An optional SQL filter expression that is applied after schema operation.

Outputs#

  • main - the only output of the mapping