Enabling Wildcard Support at the Project Level

About this task

As discussed in Default Query Syntax, Watson™ Explorer Engine supports both wildcards and regular expressions in queries. Wildcard support can be enabled either at the project level or the search collection level.

Note: Regular expressions cannot be expanded by the project, and therefore can only be used with collections configured for term expansion and federated sources that support regex queries.

In most cases, wildcards should be enabled at the search collection level. You will only need to enable wildcards at the project level if you want to add wildcard support for federated sources. (Federated sources are not associated with a search collection because they retrieve results from another search engine.)

Note: Enabling wildcards at the project level and at the search collection level are mutually exclusive. Enabling wildcards at the project level will cause any similar settings that you have made at the search collection level to be ignored. If you want to enable wildcard support at the search collection level, see Enabling Wildcard and Regular Expression Support at the Collection Level.

To enable wildcard support at the project level, do the following:


  1. Select the project's Advanced -> Metasearch tab.
  2. Click the edit button, and scroll down to the Query Modification section.
  3. Set Enable wildcard expansion to true. Once you set Enable wildcard expansion to true, Watson Explorer Engine will automatically use the default wildcard dictionary file unless a custom dictionary is identified in the Dictionary file field.


The options related to wildcard support in Watson Explorer Engine projects are the following:

  • Minimum length of wildcard term - The minimum number of sequential characters required in a query term containing a wildcard character in order for the expansion to take place. This improves performance and helps to minimize the number of query terms generated.
  • Dictionary file - The full path to the wildcard dictionary file to use for expansions.
  • Wildcard segmenter - Specifies the segmenter algorithm to use for the wildcard expansion. A segmenter is used to take sequential statements in non-segmented languages (for example, Japanese or Chinese) and divide the statement into the individual components or words.
    Note: The use of wildcard segmentation is not recommended. A query that includes wildcards expands each wildcarded statement into a list of possible statements from the wildcard dictionary. These statements are then split into components or words by the segmenter. Some of the components that are created may have only been created due to a specific wildcard, and be completely unrelated to the original query; this can have a significant impact on the usefulness of any search results.
  • Wildcard should delanguage - Set to true, this option attempts to normalize the diacritics and different writing systems before expanding wildcard operators.