Fuzzy Query

edit

The fuzzy query uses similarity based on Levenshtein edit distance for string fields, and a +/- margin on numeric and date fields.

String fields

edit

The fuzzy query generates all possible matching terms that are within the maximum edit distance specified in fuzziness and then checks the term dictionary to find out which of those generated terms actually exist in the index.

Here is a simple example:

{
    "fuzzy" : { "user" : "ki" }
}

Or with more advanced settings:

{
    "fuzzy" : {
        "user" : {
            "value" :         "ki",
            "boost" :         1.0,
            "fuzziness" :     2,
            "prefix_length" : 0,
            "max_expansions": 100
        }
    }
}
Parameters
edit

fuzziness

The maximum edit distance. Defaults to AUTO. See Fuzziness.

prefix_length

The number of initial characters which will not be “fuzzified”. This helps to reduce the number of terms which must be examined. Defaults to 0.

max_expansions

The maximum number of terms that the fuzzy query will expand to. Defaults to 50.

This query can be very heavy if prefix_length is set to 0 and if max_expansions is set to a high number. It could result in every term in the index being examined!

Numeric and date fields

edit

Performs a Range Query “around” the value using the fuzziness value as a +/- range, where:

-fuzziness <= field value <= +fuzziness

For example:

{
    "fuzzy" : {
        "price" : {
            "value" : 12,
            "fuzziness" : 2
        }
    }
}

Will result in a range query between 10 and 14. Date fields support time values, eg:

{
    "fuzzy" : {
        "created" : {
            "value" : "2010-02-05T12:05:07",
            "fuzziness" : "1d"
        }
    }
}

See Fuzziness for more details about accepted values.