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How Dissolve (Data Management) works

Release 9.2
Last modified November 29, 2010
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Use Dissolve when you want to aggregate features based on a specified attribute or attributes. For example, you could take a feature class containing sales data collected on a county-by-county basis and use Dissolve to create a layer containing contiguous sales regions based on the name of the salesperson in each county. Dissolve creates the sales regions by removing the boundaries between counties represented by the same salesperson.

Dissolve by sales region example

Dissolve fields

Features with the same value combinations for the specified fields will be aggregated (dissolved) into a single feature. The Dissolve fields are written to the Output Feature Class table.

Multipart features

Dissolve may result in multipart features being created. A multipart feature is a single feature that contains noncontiguous elements and is represented in the attribute table as one record. For example, a salesperson may be assigned a sales territory in multiple separate counties. This separation could be because of natural barriers, such as a river or lake, or could be because the counties in between are assigned to other salespeople. Suppose a salesperson is assigned to seven counties, and one of these counties does not share any borders with any of the other six counties. Dissolving the counties by salesperson would result in a single sales territory with two distinct areas. This sales territory will be one multipart feature represented in the Attribute table as one record.

Summarizing attributes

As part of the Dissolve process, the aggregated features can also include summaries of any of the attributes present in the input features. For instance, the revenue generated in the counties making up each sales region could be summed to give the total revenue for each sales region.

Coordinate system of the output

The output from the Dissolve function will be in the same coordinate system as the input feature class. The only exception to this is if you save the output from this geoprocessing operation as a feature class in an existing feature dataset. In this case, the input features will be projected for you by the Dissolve function to match the coordinate system of the feature dataset.

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