82 lines
2.3 KiB
Plaintext
82 lines
2.3 KiB
Plaintext
[[mapping-boost]]
|
|
=== `boost`
|
|
|
|
Individual fields can be _boosted_ automatically -- count more towards the relevance score
|
|
-- at query time, with the `boost` parameter as follows:
|
|
|
|
[source,console]
|
|
--------------------------------------------------
|
|
PUT my_index
|
|
{
|
|
"mappings": {
|
|
"properties": {
|
|
"title": {
|
|
"type": "text",
|
|
"boost": 2 <1>
|
|
},
|
|
"content": {
|
|
"type": "text"
|
|
}
|
|
}
|
|
}
|
|
}
|
|
--------------------------------------------------
|
|
|
|
<1> Matches on the `title` field will have twice the weight as those on the
|
|
`content` field, which has the default `boost` of `1.0`.
|
|
|
|
NOTE: The boost is applied only for term queries (prefix, range and fuzzy queries are not _boosted_).
|
|
|
|
You can achieve the same effect by using the boost parameter directly in the query, for instance the following query (with field time boost):
|
|
|
|
[source,console]
|
|
--------------------------------------------------
|
|
POST _search
|
|
{
|
|
"query": {
|
|
"match" : {
|
|
"title": {
|
|
"query": "quick brown fox"
|
|
}
|
|
}
|
|
}
|
|
}
|
|
--------------------------------------------------
|
|
|
|
is equivalent to:
|
|
|
|
[source,console]
|
|
--------------------------------------------------
|
|
POST _search
|
|
{
|
|
"query": {
|
|
"match" : {
|
|
"title": {
|
|
"query": "quick brown fox",
|
|
"boost": 2
|
|
}
|
|
}
|
|
}
|
|
}
|
|
--------------------------------------------------
|
|
|
|
|
|
deprecated[5.0.0, "Index time boost is deprecated. Instead, the field mapping boost is applied at query time. For indices created before 5.0.0, the boost will still be applied at index time."]
|
|
[WARNING]
|
|
.Why index time boosting is a bad idea
|
|
==================================================
|
|
|
|
We advise against using index time boosting for the following reasons:
|
|
|
|
* You cannot change index-time `boost` values without reindexing all of your
|
|
documents.
|
|
|
|
* Every query supports query-time boosting which achieves the same effect. The
|
|
difference is that you can tweak the `boost` value without having to reindex.
|
|
|
|
* Index-time boosts are stored as part of the <<norms,`norm`>>, which is only one
|
|
byte. This reduces the resolution of the field length normalization factor
|
|
which can lead to lower quality relevance calculations.
|
|
|
|
==================================================
|