.. _auto_dataset_join:

*JOIN DATASETS BASED ON PRIMARY KEYS*
=====================================

Joins two datasets on one or more shared primary-key columns using simple, outer, inner, or left join semantics. Use this worker when you need to merge tabular datasets from different sources into a single unified dataset before downstream analysis or modeling.

When to use
-----------

Classification: **process**.

Tagged: ``dataset``, ``inner_join``, ``join``, ``left_join``, ``merge``, ``outer_join``, ``primary_key``, ``process``.

Inputs
------

.. list-table::
   :header-rows: 1
   :widths: 20 20 20 20 20 20

   * - Label
     - ID
     - Type
     - Default
     - Required
     - Description
   * - Dataset1
     - dataset1
     - dataset
     - —
     - 
     - The primary (left-hand) dataset to join; must be a tabular dataset object — the join will fail if this is absent or invalid.
   * - Dataset2
     - dataset2
     - dataset
     - —
     - 
     - The secondary (right-hand) dataset(s) to join onto Dataset1; supports repeated inputs so multiple datasets can be merged sequentially.
   * - Join Type
     - join_type
     - scalar
     - simple
     - 
     - Join strategy: 'simple' (default, column-append with no key matching), 'outer' (all rows from both), 'inner' (only matching rows), or 'left' (all rows from Dataset1, matched rows from Dataset2).
   * - Primary Keys
     - primarykeys
     - scalar
     - —
     - 
     - Comma-separated column name(s) used as the matching key(s) between the two datasets (e.g. 'id,run_id'); leave blank for a simple side-by-side column append.
   * - Datset1 Columns To Include
     - datset1_columns_to_include
     - text
     - —
     - 
     - Subset of columns from Dataset1 to carry into the output; leave empty to include all Dataset1 columns.
   * - Datset2 Columns To Include
     - datset2_columns_to_include
     - text
     - —
     - 
     - Subset of columns from Dataset2 to carry into the output; leave empty to include all Dataset2 columns.
   * - Prefix for Dataset1
     - prefixfordataset1columns
     - scalar
     - —
     - 
     - 
   * - Prefix for Dataset 2
     - prefixfordataset2columns
     - scalar
     - —
     - 
     - Dataset 2 Column prefix

Outputs
-------

.. list-table::
   :header-rows: 1
   :widths: 20 20 20 20

   * - Label
     - ID
     - Type
     - Description
   * - dataset_join_output_1
     - dataset_join_output_1
     - dataset
     - Merged tabular dataset containing columns from both Dataset1 and Dataset2, combined according to the selected join type and primary keys.

Disciplines
-----------

- data.dataset.transform

Runnable example
----------------

A runnable example is registered for this worker. Open the example workflow on the d3VIEW canvas: `/api/workflow/example?id=dataset_join <https://www.d3view.com/api/workflow/example?id=dataset_join>`_

.. raw:: html

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   Auto-generated from <code>transformation</code> schema. Worker id: <code>dataset_join</code>. Schema hash: <code>991debb90eaa</code>. Hand-curated docs in <code>workerexamples/</code> override this page when present.
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