212 lines
5.6 KiB
Markdown
212 lines
5.6 KiB
Markdown
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---
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layout: default
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title: Constant score queries
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parent: Compound queries
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grand_parent: Query DSL
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nav_order: 40
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---
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# Constant score queries
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If you need to return documents that contain a certain word regardless of how many times the word appears, you can use a `constant_ score` query. A `constant_score` query wraps a filter query and assigns all documents in the results a relevance score equal to the value of the `boost` parameter. Thus, all returned documents have an equal relevance score, and term frequency/inverse document frequency (TF/IDF) is not considered. Filter queries do not calculate relevance scores. Further, OpenSearch caches frequently used filter queries to improve performance.
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## Example
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Use the following query to return documents that contain the word "Hamlet" in the `shakespeare` index:
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```json
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GET shakespeare/_search
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{
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"query": {
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"constant_score": {
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"filter": {
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"match": {
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"text_entry": "Hamlet"
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}
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},
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"boost": 1.2
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}
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}
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}
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```
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{% include copy-curl.html %}
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All documents in the results are assigned a relevance score of 1.2:
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<details open markdown="block">
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<summary>
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Response
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</summary>
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{: .text-delta }
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```json
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{
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"took": 8,
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"timed_out": false,
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"_shards": {
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"total": 1,
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"successful": 1,
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"skipped": 0,
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"failed": 0
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},
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"hits": {
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"total": {
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"value": 96,
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"relation": "eq"
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},
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"max_score": 1.2,
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"hits": [
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{
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"_index": "shakespeare",
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"_id": "32535",
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"_score": 1.2,
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"_source": {
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"type": "line",
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"line_id": 32536,
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"play_name": "Hamlet",
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"speech_number": 48,
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"line_number": "1.1.97",
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"speaker": "HORATIO",
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"text_entry": "Dared to the combat; in which our valiant Hamlet--"
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}
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},
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{
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"_index": "shakespeare",
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"_id": "32546",
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"_score": 1.2,
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"_source": {
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"type": "line",
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"line_id": 32547,
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"play_name": "Hamlet",
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"speech_number": 48,
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"line_number": "1.1.108",
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"speaker": "HORATIO",
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"text_entry": "His fell to Hamlet. Now, sir, young Fortinbras,"
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}
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},
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{
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"_index": "shakespeare",
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"_id": "32625",
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"_score": 1.2,
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"_source": {
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"type": "line",
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"line_id": 32626,
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"play_name": "Hamlet",
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"speech_number": 59,
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"line_number": "1.1.184",
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"speaker": "HORATIO",
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"text_entry": "Unto young Hamlet; for, upon my life,"
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}
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},
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{
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"_index": "shakespeare",
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"_id": "32633",
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"_score": 1.2,
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"_source": {
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"type": "line",
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"line_id": 32634,
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"play_name": "Hamlet",
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"speech_number": 60,
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"line_number": "",
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"speaker": "MARCELLUS",
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"text_entry": "Enter KING CLAUDIUS, QUEEN GERTRUDE, HAMLET, POLONIUS, LAERTES, VOLTIMAND, CORNELIUS, Lords, and Attendants"
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}
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},
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{
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"_index": "shakespeare",
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"_id": "32634",
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"_score": 1.2,
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"_source": {
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"type": "line",
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"line_id": 32635,
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"play_name": "Hamlet",
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"speech_number": 1,
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"line_number": "1.2.1",
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"speaker": "KING CLAUDIUS",
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"text_entry": "Though yet of Hamlet our dear brothers death"
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}
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},
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{
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"_index": "shakespeare",
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"_id": "32699",
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"_score": 1.2,
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"_source": {
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"type": "line",
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"line_id": 32700,
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"play_name": "Hamlet",
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"speech_number": 8,
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"line_number": "1.2.65",
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"speaker": "KING CLAUDIUS",
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"text_entry": "But now, my cousin Hamlet, and my son,--"
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}
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},
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{
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"_index": "shakespeare",
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"_id": "32703",
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"_score": 1.2,
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"_source": {
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"type": "line",
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"line_id": 32704,
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"play_name": "Hamlet",
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"speech_number": 12,
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"line_number": "1.2.69",
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"speaker": "QUEEN GERTRUDE",
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"text_entry": "Good Hamlet, cast thy nighted colour off,"
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}
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},
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{
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"_index": "shakespeare",
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"_id": "32723",
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"_score": 1.2,
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"_source": {
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"type": "line",
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"line_id": 32724,
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"play_name": "Hamlet",
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"speech_number": 16,
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"line_number": "1.2.89",
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"speaker": "KING CLAUDIUS",
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"text_entry": "Tis sweet and commendable in your nature, Hamlet,"
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}
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},
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{
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"_index": "shakespeare",
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"_id": "32754",
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"_score": 1.2,
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"_source": {
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"type": "line",
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"line_id": 32755,
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"play_name": "Hamlet",
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"speech_number": 17,
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"line_number": "1.2.120",
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"speaker": "QUEEN GERTRUDE",
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"text_entry": "Let not thy mother lose her prayers, Hamlet:"
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}
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},
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{
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"_index": "shakespeare",
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"_id": "32759",
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"_score": 1.2,
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"_source": {
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"type": "line",
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"line_id": 32760,
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"play_name": "Hamlet",
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"speech_number": 19,
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"line_number": "1.2.125",
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"speaker": "KING CLAUDIUS",
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"text_entry": "This gentle and unforced accord of Hamlet"
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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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</details>
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## Parameters
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The following table lists all top-level parameters supported by `constant_score `queries.
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Parameter | Description
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:--- | :---
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`filter` | The filter query that a document must match to be returned in the results. Required.
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`boost` | A floating-point value that is assigned as the relevance score to all returned documents. Optional. Default is 1.0.
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