190 lines
5.2 KiB
Plaintext
190 lines
5.2 KiB
Plaintext
[[search-explain]]
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=== Explain API
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Returns information about why a specific document matches (or doesn't match) a
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query.
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[source,console]
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--------------------------------------------------
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GET /twitter/_explain/0
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{
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"query" : {
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"match" : { "message" : "elasticsearch" }
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}
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}
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--------------------------------------------------
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// TEST[setup:twitter]
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[[sample-api-request]]
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==== {api-request-title}
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`GET /<index>/_explain/<id>`
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`POST /<index>/_explain/<id>`
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[[sample-api-desc]]
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==== {api-description-title}
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The explain API computes a score explanation for a query and a specific
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document. This can give useful feedback whether a document matches or
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didn't match a specific query.
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[[sample-api-path-params]]
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==== {api-path-parms-title}
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`<id>`::
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(Required, integer) Defines the document ID.
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`<index>`::
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+
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--
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(Required, string)
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Index names used to limit the request.
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Only a single index name can be provided to this parameter.
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--
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[[sample-api-query-params]]
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==== {api-query-parms-title}
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include::{es-repo-dir}/rest-api/common-parms.asciidoc[tag=analyzer]
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include::{es-repo-dir}/rest-api/common-parms.asciidoc[tag=analyze_wildcard]
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include::{es-repo-dir}/rest-api/common-parms.asciidoc[tag=default_operator]
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include::{es-repo-dir}/rest-api/common-parms.asciidoc[tag=df]
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include::{es-repo-dir}/rest-api/common-parms.asciidoc[tag=lenient]
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include::{es-repo-dir}/rest-api/common-parms.asciidoc[tag=preference]
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include::{es-repo-dir}/rest-api/common-parms.asciidoc[tag=search-q]
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`stored_fields`::
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(Optional, string) A comma-separated list of stored fields to return in the
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response.
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include::{es-repo-dir}/rest-api/common-parms.asciidoc[tag=index-routing]
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include::{es-repo-dir}/rest-api/common-parms.asciidoc[tag=source]
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include::{es-repo-dir}/rest-api/common-parms.asciidoc[tag=source_excludes]
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include::{es-repo-dir}/rest-api/common-parms.asciidoc[tag=source_includes]
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[[sample-api-request-body]]
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==== {api-request-body-title}
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include::{es-repo-dir}/rest-api/common-parms.asciidoc[tag=query]
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[[sample-api-example]]
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==== {api-examples-title}
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[source,console]
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--------------------------------------------------
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GET /twitter/_explain/0
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{
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"query" : {
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"match" : { "message" : "elasticsearch" }
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}
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}
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--------------------------------------------------
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// TEST[setup:twitter]
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The API returns the following response:
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[source,console-result]
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--------------------------------------------------
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{
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"_index":"twitter",
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"_type":"_doc",
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"_id":"0",
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"matched":true,
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"explanation":{
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"value":1.6943598,
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"description":"weight(message:elasticsearch in 0) [PerFieldSimilarity], result of:",
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"details":[
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{
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"value":1.6943598,
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"description":"score(freq=1.0), computed as boost * idf * tf from:",
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"details":[
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{
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"value":2.2,
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"description":"boost",
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"details":[]
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},
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{
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"value":1.3862944,
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"description":"idf, computed as log(1 + (N - n + 0.5) / (n + 0.5)) from:",
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"details":[
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{
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"value":1,
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"description":"n, number of documents containing term",
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"details":[]
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},
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{
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"value":5,
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"description":"N, total number of documents with field",
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"details":[]
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}
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]
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},
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{
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"value":0.5555556,
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"description":"tf, computed as freq / (freq + k1 * (1 - b + b * dl / avgdl)) from:",
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"details":[
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{
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"value":1.0,
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"description":"freq, occurrences of term within document",
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"details":[]
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},
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{
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"value":1.2,
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"description":"k1, term saturation parameter",
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"details":[]
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},
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{
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"value":0.75,
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"description":"b, length normalization parameter",
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"details":[]
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},
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{
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"value":3.0,
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"description":"dl, length of field",
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"details":[]
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},
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{
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"value":5.4,
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"description":"avgdl, average length of field",
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"details":[]
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}
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]
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}
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]
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}
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]
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}
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}
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--------------------------------------------------
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There is also a simpler way of specifying the query via the `q` parameter. The
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specified `q` parameter value is then parsed as if the `query_string` query was
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used. Example usage of the `q` parameter in the
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explain API:
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[source,console]
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--------------------------------------------------
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GET /twitter/_explain/0?q=message:search
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--------------------------------------------------
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// TEST[setup:twitter]
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The API returns the same result as the previous request.
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