Category Component 25.2
Category Component Help

# 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 `DREADDDATA` actions—use the `KillDuplicates` configuration parameter in the `[Server]` section of the configuration file.

IMPORTANT: You must enable deduplication before you start indexing documents into the 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.

Related Topics

- Use KillDuplicatesChecksumField to Prevent Unnecessary Indexing

To enable deduplication as the default for all indexing jobs

1. Open the Content component configuration file in a text editor.

2. In the `[Server]` section, set the `KillDuplicates` parameter to `REFERENCE`, `REFERENCEMATCHN`, the names of the `ReferenceType` fields to use to determine which documents are duplicates, or a combination of `ReferenceType` field and a field that contains a document version number. For more information about these options, see Deduplication Options—KillDuplicates, or refer to the Content Component Help.

   You can identify fields that contain document references by setting up an appropriate field process. When you index a document that has the same value in the same `ReferenceType` field as an existing document in Content, Content detects the duplicate. It deletes the existing document and replaces it with the new one.

3. Save and close the configuration file.

4. Restart the Content component for your changes to take effect.

You can now index documents into the Content component.

Related Topics

- Deduplication Options—KillDuplicates

- Set up ReferenceType Fields

## 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:

    [SetReferenceFields]
    Property=Reference
    PropertyFieldCSVs=*/DREREFERENCE,*/URL

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:

    [SetReferenceFields]
    Property=Reference
    PropertyFieldCSVs=*/DREREFERENCE

    [SetMoreReferenceFields]
    Property=Reference
    PropertyFieldCSVs=*/URL

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.

Related Topics

- Set up ReferenceType Fields

## 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.

NOTE: 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`.

NOTE: 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.

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Version 25.2 | Last updated April 2025

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Product: Knowledge Discovery Category Component 25.2

Topic Title: Enable Deduplication for all Index Jobs