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

The fuzzy query uses similarity based on Levenshtein edit distance.

==== String fields

The `fuzzy` query generates 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. The final query uses up to `max_expansions` matching terms.

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`.

`transpositions`::

    Whether fuzzy transpositions (`ab` -> `ba`) are supported.
    Default is `true`.

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!