Enable Deduplication for all Index Jobs

To enable deduplication for all indexing jobs—in other words, to set deduplication by default for the DREADD and DREADDATA actions—use the KillDuplicates configuration parameter in the [Server] section of the configuration file.


You must enable deduplication before you start indexing documents into the IDOL Content component.

You can use the KillDuplicatesChecksumField parameter to configure Content to reverse normal deduplication and retain the existing document instead of the incoming document, based on the value of a specified field in the incoming document.

You can use the KillDuplicatesPreserveFields parameter to configure one or more IDX fields that Content copies to a newer version of a duplicate document.

Limit ReferenceType Fields used for Deduplication

You identify fields as ReferenceType fields through field processes. If you list multiple fields in the same PropertyFieldCSVs parameter where you list the FieldName for deduplication, Content uses all the fields to eliminate duplicate documents. For example:


In this example, Content uses both the DREREFERENCE field and URL field to eliminate duplicate copies if you set KillDuplicates to DREREFERENCE.

If you want to define multiple ReferenceType fields but do not want to use them all for duplicate elimination, set up multiple field processes. For example:



In this example, Content uses only the DREREFERENCE field to eliminate duplicate copies if you set KillDuplicates to DREREFERENCE. It does not use the URL field.

Use KillDuplicatesChecksumField to Prevent Unnecessary Indexing

By default, when Content detects that a new document is a duplicate of an existing one, it replaces the existing document with the new one.

For either of these two KillDuplicates options, you can also use the KillDuplicatesChecksumField configuration parameter to specify a checksum field. Content then checks the value of this field in both documents. If the value is the same, Content keeps the existing document rather than replacing it with the new document.

This process prevents unnecessary updates. For example, when refetching a Web site, use KillDuplicatesChecksumField to configure Content to update the index for this site only if the site has changed.


The KillDuplicatesChecksumField must be a ReferenceType field.

Use KillDuplicatesPreserveFields to Preserve a Field

If there is a field that you want to keep in all versions of a document, regardless of whether it is later deleted or changed, you can use the KillDuplicatesPreserveFields configuration parameter.

To preserve fields, set KillDuplicatesPreserveFields to a comma-separated list of fields that you want to save.

When Content receives a duplicate document, it copies this field from the existing version of the document to the newer version when it performs KillDuplicates.


If there is more than one copy of the document in the Content index when a new version arrives, Content copies the preserve field from the existing duplicate with the highest document ID.