A wildcard ( * )is treated as a character pattern that matches many index terms at once. ATG Search uses asterisks in a term to denote a wildcard, where the asterisk can match zero or more other characters. At least one other non-asterisk character must appear in the query term. The wildcard can be used in the following ways:
At the end of the term. For example, book* matches any index term that begins with the sub-string book, such as book, books, booking, and bookshelf.
At the beginning of the term, such as with *desk, which matches terms such as desk, workdesk, and computerdesk.
Within a term, such as inst*ion, which matches index terms such as installation and institution.
Multiple wildcards, such as *install*, match any index term with install in the middle.
Wildcards are a form of term expansion, because a single query term is replaced with alternative terms. But in this case, the expansions are not from a thesaurus, but based solely on the characters of the terms in the index and the wildcard pattern.
Note: Wildcard patterns expand to index terms, not to morphological forms of words, so the results are not always obvious. For example, *desk expands to workdesk, which retrieves all forms of workdesk, including workdesks, which doesn’t really match the wildcard pattern due to the trailing s. This behavior is by design and consistent with the rest of ATG Search’s query handling and search results. Users should understand that the wildcards are matching against the dictionary of index terms, not literally across the document text.
Wildcards can expand to hundreds or thousands of index terms with patterns like s*. To prevent slowdowns and poor search results, ATG Search limits the number of expansions a wildcard can produce. This limit is configurable, as described in the Wild Card Maximum section of the Query Component Reference chapter. The limit defaults to 20.
