Text score and synonym support

A text search server supports the use of synonyms to improve the results of a query. In addition, text score might be returned as part of the query results.

Text score

Db2 might request that a text score be returned as part of the query results. A text score is a value between 0 (zero) and 1 up to 3 decimal points (for example, 0.000 to 1.000). A text score denotes how closely a result matches the query relative to all of the other documents in the text search index.

A text score is composed from various factors. These factors include the general importance of the search terms (based on the frequency of the terms in each document and offset by the frequency of the terms across all documents) and the proximity of occurrences of the search terms. By default, a text score is not returned.

Synonym support

You can use synonyms to improve the results for a query. Using synonyms might increase the number of query results by causing more documents to match a query. However, using synonyms might also decrease the precision of a query and make it more difficult to find a small number of documents that match the exact search criteria.

By default, synonyms are not used for a query. To use synonyms for a query, create a synonym dictionary, and add the synonym dictionary to a collection by using the Synonym Tool.