Phrase module options

The Phrase module has a variety of options that you use to customize its behavior.

These options are configured via Boolean attributes:

These attributes belong to the RELRANK_PHRASE element.

Approximate matching

Approximate matching provides higher-performance matching, as compared to the standard Phrase module, with somewhat less exact results.

With approximate matching enabled, the Phrase module looks at a limited number of positions in each result that a phrase match could possibly exist, rather than all the positions. Only this limited number of possible occurrences is considered, regardless of whether there are later occurrences that are better, more relevant matches.

The approximate setting is appropriate in cases where the runtime performance of the standard Phrase module is inadequate because of large result contents and/or high site load.

Query expansion

Applying spelling correction, thesaurus, and stemming adjustments to the original phrase is generically known as query expansion. With query expansion enabled, the Phrase module ranks results that match a phrase’s expanded forms in the same stratum as results that match the original phrase.

Consider the following example:
  • A thesaurus entry exists that expands "US" to "United States".
  • The user queries for "US government".

The query "US government" is expanded to "United States government" for matching purposes, but the Phrase module gives a score of two to any results matching "United States government" because the original, unexpanded version of the query, "US government", only had two terms.

Subphrasing

Subphrasing ranks results based on the length of their subphrase matches. In other words, results that match three terms are considered more relevant than results that match two terms, and so on.

A subphrase is defined as a contiguous subset of the query terms the user entered, in the order that he or she entered them. For example, the query "fax cover sheets" contains the subphrases "fax", "cover", "sheets", "fax cover", "cover sheets", and "fax cover sheets", but not "fax sheets".

Content contained inside nested quotes in a phrase is treated as one term. For example, consider the following phrase: 
the question is "to be or not to be"

The quoted text ("to be or not to be") is treated as one query term, so this example consists of four query terms even though it has a total of nine words.

When subphrasing is not enabled, results are ranked into two strata: those that matched the entire phrase and those that did not.