[[query-dsl-fuzzy-query]]
=== Fuzzy Query

The fuzzy query uses similarity based on Levenshtein edit distance.

==== String fields

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:

[source,js]
--------------------------------------------------
GET /_search
{
    "query": {
       "fuzzy" : { "user" : "ki" }
    }
}
--------------------------------------------------
// CONSOLE

Or with more advanced settings:

[source,js]
--------------------------------------------------
GET /_search
{
    "query": {
        "fuzzy" : {
            "user" : {
                "value" :         "ki",
                    "boost" :         1.0,
                    "fuzziness" :     2,
                    "prefix_length" : 0,
                    "max_expansions": 100
            }
        }
    }
}
--------------------------------------------------
// CONSOLE

[float]
===== Parameters

[horizontal]
`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`.


WARNING: 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!


