Scoring fuzziness

[[fuzzy-scoring]] === Scoring Fuzziness

Users love fuzzy queries. They assume that these queries will somehow magically find the right combination of proper spellings.((("fuzzy queries", "scoring fuzziness")))((("typoes and misspellings", "scoring fuzziness")))((("relevance scores", "fuzziness and"))) Unfortunately, the truth is somewhat more prosaic.

Imagine that we have 1,000 documents containing Schwarzenegger,'' and just one document with the misspellingSchwarzeneger.'' According to the theory of <>, the misspelling is much more relevant than the correct spelling, because it appears in far fewer documents!

In other words, if we were to treat fuzzy matches((("match query", "fuzzy match query"))) like any other match, we would favor misspellings over correct spellings, which would make for grumpy users.

TIP: Fuzzy matching should not be used for scoring purposes--only to widen the net of matching terms in case there are misspellings.

By default, the match query gives all fuzzy matches the constant score of 1. This is sufficient to add potential matches onto the end of the result list, without interfering with the relevance scoring of nonfuzzy queries.

[TIP]

Fuzzy queries alone are much less useful than they initially appear. They are better used as part of a `bigger'' feature, such as the _search-as-you-type_ http://bit.ly/1IChV5j[completionsuggester] or the _did-you-mean_ http://bit.ly/1IOj5ZG[phrase` suggester].

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