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Merge Join Transformation

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The Merge Join transformation provides an output that is generated by joining two sorted datasets using a FULL, LEFT, or INNER join. For example, you can use a LEFT join to join a table that includes product information with a table that lists the country/region in which a product was manufactured. The result is a table that lists all products and their country/region of origin.

You can configure the Merge Join transformation in the following ways:

  • Specify the join is a FULL, LEFT, or INNER join.

  • Specify the columns the join uses.

  • Specify whether the transformation handles null values as equal to other nulls.

    Note

    If null values are not treated as equal values, the transformation handles null values like the SQL Server Database Engine does.

This transformation has two inputs and one output. It does not support an error output.

Input Requirements

The Merge Join Transformation requires sorted data for its inputs. For more information about this important requirement, see Sort Data for the Merge and Merge Join Transformations.

Join Requirements

The Merge Join transformation requires that the joined columns have matching metadata. For example, you cannot join a column that has a numeric data type with a column that has a character data type. If the data has a string data type, the length of the column in the second input must be less than or equal to the length of the column in the first input with which it is merged.

Buffer Throttling

You no longer have to configure the value of the MaxBuffersPerInput property because Microsoft has made changes that reduce the risk that the Merge Join transformation will consume excessive memory. This problem sometimes occurred when the multiple inputs of the Merge Join produced data at uneven rates.

You can set properties through the SSIS Designer or programmatically.

For information about how to set properties of this transformation, click one of the following topics:

See Also

Merge Join Transformation Editor
Merge Transformation
Union All Transformation
Integration Services Transformations