Score search terms by inverse document frequency (IDF)

Enable term frequency–inverse document frequency (TF-IDF) to increase the search result scores of search terms that appear more frequently in a document, but less frequently in the whole collection of searchable documents.

Before you begin

Role required: admin

To enable TF-IDF scoring, a text index must be present for the table. Make sure that text indexing is enabled for the table before changing the query mode. See Enable text indexing for a table.

About this task

Administrators can enable TF-IDF scoring on a table to improve search results. The Knowledge table [kb_knowledge] has TF-IDF scoring enabled by default.

Note: This task requires that you regenerate an index and therefore should be done with system performance in mind. Regenerating an index may take a while to complete depending on table size and other factors. You may notice performance degradation or incomplete search results while the system regenerates the index.

Procedure

  1. Navigate to the system dictionary and open the entry for the desired table.
  2. In the Attributes related list, click New.
  3. In the Attributes field, select Text search Enable IDF.
  4. Click Submit.
    The Enable IDF Score check box in the table's text index record can now be configured.
  5. Navigate to System Definition > Text Indexes.
  6. Open the text index created for the table.
  7. Select Enable IDF Score.
  8. Under Related Links, click Regenerate Document Frequency.
    Regenerating document frequency is a one-time task. Regenerate document frequency when TF-IDF scoring is first enabled for a table.
  9. Configure the desired notification and click OK.