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How Column-Level Lineage Works

Collate supports rich column-level lineage for understanding the relationship between tables and to perform impact analysis. Users can manually edit both the table and column level lineage to capture any information that is not automatically surfaced. You can generate the column-level lineage automatically by running the Lineage Agent.

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Manually Edit Column Level Lineage

Collate supports manual editing of both table-level and column-level lineage. Use it to add links that are not detected automatically. To link columns by hand:

1. Open the table and select the Lineage tab.
2. Click Edit (the pencil icon) in the lineage toolbar. The asset panel opens next to the graph.
3. If the table that holds the column you want to trace is not in the graph, add it first:
   • In the asset panel, choose the asset type, such as Tables.
   • Search for the table and add it to the graph.
   
4. Find the column in the source table. Each column has an anchor point on its edge.
5. Drag from the anchor point of the source column to the anchor point of the column it feeds in the other table.
6. Repeat for each column you want to link.
7. Optional: To remove a link, select the x icon on the connecting line.
8. Save your changes.

Watch the video on editing column-level lineage.

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Metric Column Lineage

A metric is often calculated from a single column. Link the column to the metric so the lineage shows exactly which field feeds the metric. For example, link sales.amount to the metric Total Sales.

• Direction: Connect a column to a metric (column feeds the metric), or a metric to a column.
• Endpoint: A metric has no columns of its own. In column-level lineage, the metric appears as one connection point that carries the metric’s own name.
• Visibility: The connection point appears on a metric node at the Field-level Lineage level or in edit mode. In the default view, a metric node shows no connection point.
• Impact Analysis: The column-to-metric link also appears in the column-level Impact Analysis view, so you can see which metrics depend on a column before you change it.

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Link a Column to a Metric

Before you start, make sure you can edit the metric and the table that holds the column.

1. Open the metric and select the Lineage tab.
2. Select Edit (the pencil icon) in the lineage toolbar.
3. If the table that holds the column is not in the graph, add it from the asset panel. For more information, see Manually Edit Column-Level Lineage.
4. Select the Layers button and, under Level, select Field-level Lineage so the table’s columns are listed.
5. Drag from the anchor point beside the column to the anchor point on the metric.
6. Save your changes.

To remove the link, select the x icon on the connecting line in edit mode.