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Join on Sorted Keys

Joins rows based on sorted key fields

Processing

The step accepts two streams of rows, coming from two input gates left and right. It matches left and right rows based on matching values in corresponding key fields.

Join Algorithm

The step uses a fast join algorithm that requires both row streams to be be sorted on key fields in ascending order with nil values last, if any.

Settings

Name Type Description
Join
Mode
 string

The join mode to use. Possible modes are:

  • INNER
    Output contains only rows for which a matching row on the other side has been found. Any rows without matches are omitted.
  • LEFT OUTER
    Output contains all left rows. If any left rows have no match on the right side, the right fields on the output row are set to nil.
  • RIGHT OUTER
    Output stream contains all right rows. If any right rows have no match on the left side, the left fields on the output row are set to nil.
  • FULL OUTER
    Output contains all left and all right rows. If any rows have no match on the other side, the other side’s fields on the output row are set to nil.

Evaluated once when step initializes
Key Fields
 N/A Key fields to join on. Both left and right inputs must be sorted by the key fields specified.
Output
Output
 N/A

Determines the structure of output rows:

  • left fields, then right fields
    Output rows contain fields from left and right rows, in order. In case of field name conflicts right row values are preserved.
  • right fields, then left fields
    Output rows contain fields from right and left rows, in order. In case of field name conflicts left row values are preserved.
  • left fields only
    Output rows contain fields from left rows only. Fields from the right row can be placed manually in the output using results.right
  • right fields only
    Output rows contain fields from right rows only. Any fields from the left row can be placed manually in the output using results.left
  • none
    Output rows are empty. Values from left and right rows must be placed manually in the output using results.left and results.right
Left Fields Prefix
 N/A Field names from the left side are prefixed with this in the output.
Right Fields Prefix
 N/A Field names from the right side are prefixed with this in the output.

Results

Name Type Description
left
 dict Currently matched left row. This value is nil for empty joins that are the result of an outer join.
right
 dict Currently matched right row. This value is nil for empty joins that are the result of an outer join.
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