66 lines
2.4 KiB
Plaintext
66 lines
2.4 KiB
Plaintext
[[query-dsl-flt-query]]
|
|
=== Fuzzy Like This Query
|
|
|
|
Fuzzy like this query find documents that are "like" provided text by
|
|
running it against one or more fields.
|
|
|
|
[source,js]
|
|
--------------------------------------------------
|
|
{
|
|
"fuzzy_like_this" : {
|
|
"fields" : ["name.first", "name.last"],
|
|
"like_text" : "text like this one",
|
|
"max_query_terms" : 12
|
|
}
|
|
}
|
|
--------------------------------------------------
|
|
|
|
`fuzzy_like_this` can be shortened to `flt`.
|
|
|
|
The `fuzzy_like_this` top level parameters include:
|
|
|
|
[cols="<,<",options="header",]
|
|
|=======================================================================
|
|
|Parameter |Description
|
|
|`fields` |A list of the fields to run the more like this query against.
|
|
Defaults to the `_all` field.
|
|
|
|
|`like_text` |The text to find documents like it, *required*.
|
|
|
|
|`ignore_tf` |Should term frequency be ignored. Defaults to `false`.
|
|
|
|
|`max_query_terms` |The maximum number of query terms that will be
|
|
included in any generated query. Defaults to `25`.
|
|
|
|
|`min_similarity` |The minimum similarity of the term variants. Defaults
|
|
to `0.5`.
|
|
|
|
|`prefix_length` |Length of required common prefix on variant terms.
|
|
Defaults to `0`.
|
|
|
|
|`boost` |Sets the boost value of the query. Defaults to `1.0`.
|
|
|
|
|`analyzer` |The analyzer that will be used to analyze the text.
|
|
Defaults to the analyzer associated with the field.
|
|
|=======================================================================
|
|
|
|
[float]
|
|
==== How it Works
|
|
|
|
Fuzzifies ALL terms provided as strings and then picks the best n
|
|
differentiating terms. In effect this mixes the behaviour of FuzzyQuery
|
|
and MoreLikeThis but with special consideration of fuzzy scoring
|
|
factors. This generally produces good results for queries where users
|
|
may provide details in a number of fields and have no knowledge of
|
|
boolean query syntax and also want a degree of fuzzy matching and a fast
|
|
query.
|
|
|
|
For each source term the fuzzy variants are held in a BooleanQuery with
|
|
no coord factor (because we are not looking for matches on multiple
|
|
variants in any one doc). Additionally, a specialized TermQuery is used
|
|
for variants and does not use that variant term's IDF because this would
|
|
favor rarer terms, such as misspellings. Instead, all variants use the
|
|
same IDF ranking (the one for the source query term) and this is
|
|
factored into the variant's boost. If the source query term does not
|
|
exist in the index the average IDF of the variants is used.
|