You're viewing version 2.13 of the OpenSearch documentation. This version is no longer maintained. For the latest version, see the current documentation. For information about OpenSearch version maintenance, see Release Schedule and Maintenance Policy.
Oversample processor
The oversample
request processor multiplies the size
parameter of the search request by a specified sample_factor
(>= 1.0), saving the original value in the original_size
pipeline variable. The oversample
processor is designed to work with the truncate_hits
response processor but may be used on its own.
Request fields
The following table lists all request fields.
Field | Data type | Description |
---|---|---|
sample_factor | Float | The multiplicative factor (>= 1.0) that will be applied to the size parameter before processing the search request. Required. |
context_prefix | String | May be used to scope the original_size variable in order to avoid collisions. Optional. |
tag | String | The processor’s identifier. Optional. |
description | String | A description of the processor. Optional. |
ignore_failure | Boolean | If true , OpenSearch ignores any failure of this processor and continues to run the remaining processors in the search pipeline. Optional. Default is false . |
Example
The following example demonstrates using a search pipeline with an oversample
processor.
Setup
Create an index named my_index
containing many documents:
POST /_bulk
{ "create":{"_index":"my_index","_id":1}}
{ "doc": { "title" : "document 1" }}
{ "create":{"_index":"my_index","_id":2}}
{ "doc": { "title" : "document 2" }}
{ "create":{"_index":"my_index","_id":3}}
{ "doc": { "title" : "document 3" }}
{ "create":{"_index":"my_index","_id":4}}
{ "doc": { "title" : "document 4" }}
{ "create":{"_index":"my_index","_id":5}}
{ "doc": { "title" : "document 5" }}
{ "create":{"_index":"my_index","_id":6}}
{ "doc": { "title" : "document 6" }}
{ "create":{"_index":"my_index","_id":7}}
{ "doc": { "title" : "document 7" }}
{ "create":{"_index":"my_index","_id":8}}
{ "doc": { "title" : "document 8" }}
{ "create":{"_index":"my_index","_id":9}}
{ "doc": { "title" : "document 9" }}
{ "create":{"_index":"my_index","_id":10}}
{ "doc": { "title" : "document 10" }}
Creating a search pipeline
The following request creates a search pipeline named my_pipeline
with an oversample
request processor that requests 50% more hits than specified in size
:
PUT /_search/pipeline/my_pipeline
{
"request_processors": [
{
"oversample" : {
"tag" : "oversample_1",
"description" : "This processor will multiply `size` by 1.5.",
"sample_factor" : 1.5
}
}
]
}
Using a search pipeline
Search for documents in my_index
without a search pipeline:
POST /my_index/_search
{
"size": 5
}
The response contains five hits:
Response
{
"took" : 3,
"timed_out" : false,
"_shards" : {
"total" : 1,
"successful" : 1,
"skipped" : 0,
"failed" : 0
},
"hits" : {
"total" : {
"value" : 10,
"relation" : "eq"
},
"max_score" : 1.0,
"hits" : [
{
"_index" : "my_index",
"_id" : "1",
"_score" : 1.0,
"_source" : {
"doc" : {
"title" : "document 1"
}
}
},
{
"_index" : "my_index",
"_id" : "2",
"_score" : 1.0,
"_source" : {
"doc" : {
"title" : "document 2"
}
}
},
{
"_index" : "my_index",
"_id" : "3",
"_score" : 1.0,
"_source" : {
"doc" : {
"title" : "document 3"
}
}
},
{
"_index" : "my_index",
"_id" : "4",
"_score" : 1.0,
"_source" : {
"doc" : {
"title" : "document 4"
}
}
},
{
"_index" : "my_index",
"_id" : "5",
"_score" : 1.0,
"_source" : {
"doc" : {
"title" : "document 5"
}
}
}
]
}
}
To search with a pipeline, specify the pipeline name in the search_pipeline
query parameter:
POST /my_index/_search?search_pipeline=my_pipeline
{
"size": 5
}
The response contains 8 documents (5 * 1.5 = 7.5, rounded up to 8):
Response
{
"took" : 13,
"timed_out" : false,
"_shards" : {
"total" : 1,
"successful" : 1,
"skipped" : 0,
"failed" : 0
},
"hits" : {
"total" : {
"value" : 10,
"relation" : "eq"
},
"max_score" : 1.0,
"hits" : [
{
"_index" : "my_index",
"_id" : "1",
"_score" : 1.0,
"_source" : {
"doc" : {
"title" : "document 1"
}
}
},
{
"_index" : "my_index",
"_id" : "2",
"_score" : 1.0,
"_source" : {
"doc" : {
"title" : "document 2"
}
}
},
{
"_index" : "my_index",
"_id" : "3",
"_score" : 1.0,
"_source" : {
"doc" : {
"title" : "document 3"
}
}
},
{
"_index" : "my_index",
"_id" : "4",
"_score" : 1.0,
"_source" : {
"doc" : {
"title" : "document 4"
}
}
},
{
"_index" : "my_index",
"_id" : "5",
"_score" : 1.0,
"_source" : {
"doc" : {
"title" : "document 5"
}
}
},
{
"_index" : "my_index",
"_id" : "6",
"_score" : 1.0,
"_source" : {
"doc" : {
"title" : "document 6"
}
}
},
{
"_index" : "my_index",
"_id" : "7",
"_score" : 1.0,
"_source" : {
"doc" : {
"title" : "document 7"
}
}
},
{
"_index" : "my_index",
"_id" : "8",
"_score" : 1.0,
"_source" : {
"doc" : {
"title" : "document 8"
}
}
}
]
}
}