82 lines
2.2 KiB
Plaintext
82 lines
2.2 KiB
Plaintext
[[mapping-boost]]
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=== `boost`
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Individual fields can be _boosted_ automatically -- count more towards the relevance score
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-- at query time, with the `boost` parameter as follows:
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[source,console]
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--------------------------------------------------
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PUT my-index-000001
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{
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"mappings": {
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"properties": {
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"title": {
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"type": "text",
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"boost": 2 <1>
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},
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"content": {
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"type": "text"
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}
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}
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}
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}
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--------------------------------------------------
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<1> Matches on the `title` field will have twice the weight as those on the
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`content` field, which has the default `boost` of `1.0`.
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NOTE: The boost is applied only for term queries (prefix, range and fuzzy queries are not _boosted_).
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You can achieve the same effect by using the boost parameter directly in the query, for instance the following query (with field time boost):
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[source,console]
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--------------------------------------------------
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POST _search
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{
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"query": {
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"match": {
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"title": {
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"query": "quick brown fox"
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}
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}
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}
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}
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--------------------------------------------------
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is equivalent to:
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[source,console]
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--------------------------------------------------
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POST _search
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{
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"query": {
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"match": {
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"title": {
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"query": "quick brown fox",
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"boost": 2
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}
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}
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}
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}
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--------------------------------------------------
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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."]
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[WARNING]
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.Why index time boosting is a bad idea
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==================================================
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We advise against using index time boosting for the following reasons:
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* You cannot change index-time `boost` values without reindexing all of your
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documents.
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* Every query supports query-time boosting which achieves the same effect. The
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difference is that you can tweak the `boost` value without having to reindex.
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* Index-time boosts are stored as part of the <<norms,`norm`>>, which is only one
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byte. This reduces the resolution of the field length normalization factor
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which can lead to lower quality relevance calculations.
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==================================================
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