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. Note that you must enable deduplication before you start indexing documents into HPE IDOL Server.

You can use the KillDuplicatesChecksumField parameter to configure HPE IDOL 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 HPE IDOL Server 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, HPE IDOL Server uses all the fields to eliminate duplicate documents. For example:


In this example, HPE IDOL Server 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, HPE IDOL Server 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 HPE IDOL Server 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. HPE IDOL Server then checks the value of this field in both documents. If the value is the same, HPE IDOL Server 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 HPE IDOL 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 HPE IDOL Server 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 HPE IDOL Server index when a new version arrives, HPE IDOL Server copies the preserve field from the existing duplicate with the highest document ID.