The following options can be applied to all of the REST APIs.

Pretty Results

When appending ?pretty=true to any request made, the JSON returned will be pretty formatted (use it for debugging only!). Another option is to set ?format=yaml which will cause the result to be returned in the (sometimes) more readable yaml format.

Human readable output

Statistics are returned in a format suitable for humans (e.g. "exists_time": "1h" or "size": "1kb") and for computers (e.g. "exists_time_in_millis": 3600000 or "size_in_bytes": 1024). The human readable values can be turned off by adding ?human=false to the query string. This makes sense when the stats results are being consumed by a monitoring tool, rather than intended for human consumption. The default for the human flag is false.

Date Math

Most parameters which accept a formatted date value — such as gt and lt in range queries, or from and to in daterange aggregations — understand date maths.

The expression starts with an anchor date, which can either be now, or a date string ending with ||. This anchor date can optionally be followed by one or more maths expressions:

The supported time units differ from those supported by time units for durations. The supported units are:

Assuming now is 2001-01-01 12:00:00, some examples are:

Response Filtering

All REST APIs accept a filter_path parameter that can be used to reduce the response returned by Elasticsearch. This parameter takes a comma separated list of filters expressed with the dot notation:

GET /_search?q=elasticsearch&filter_path=took,hits.hits._id,hits.hits._score

Responds:

{
  "took" : 3,
  "hits" : {
    "hits" : [
      {
        "_id" : "0",
        "_score" : 1.6375021
      }
    ]
  }
}

It also supports the * wildcard character to match any field or part of a field’s name:

GET /_cluster/state?filter_path=metadata.indices.*.stat*

Responds:

{
  "metadata" : {
    "indices" : {
      "twitter": {"state": "open"}
    }
  }
}

And the ** wildcard can be used to include fields without knowing the exact path of the field. For example, we can return the Lucene version of every segment with this request:

GET /_cluster/state?filter_path=routing_table.indices.**.state

Responds:

{
  "routing_table": {
    "indices": {
      "twitter": {
        "shards": {
          "0": [{"state": "STARTED"}, {"state": "UNASSIGNED"}]
        }
      }
    }
  }
}

It is also possible to exclude one or more fields by prefixing the filter with the char -:

GET /_count?filter_path=-_shards

Responds:

{
  "count" : 5
}

And for more control, both inclusive and exclusive filters can be combined in the same expression. In this case, the exclusive filters will be applied first and the result will be filtered again using the inclusive filters:

GET /_cluster/state?filter_path=metadata.indices.*.state,-metadata.indices.logstash-*

Responds:

{
  "metadata" : {
    "indices" : {
      "index-1" : {"state" : "open"},
      "index-2" : {"state" : "open"},
      "index-3" : {"state" : "open"}
    }
  }
}

Note that Elasticsearch sometimes returns directly the raw value of a field, like the _source field. If you want to filter _source fields, you should consider combining the already existing _source parameter (see Get API for more details) with the filter_path parameter like this:

POST /library/book?refresh
{"title": "Book #1", "rating": 200.1}
POST /library/book?refresh
{"title": "Book #2", "rating": 1.7}
POST /library/book?refresh
{"title": "Book #3", "rating": 0.1}
GET /_search?filter_path=hits.hits._source&_source=title&sort=rating:desc

{
  "hits" : {
    "hits" : [ {
      "_source":{"title":"Book #1"}
    }, {
      "_source":{"title":"Book #2"}
    }, {
      "_source":{"title":"Book #3"}
    } ]
  }
}

Flat Settings

The flat_settings flag affects rendering of the lists of settings. When the flat_settings flag is true, settings are returned in a flat format:

GET twitter/_settings?flat_settings=true

Returns:

{
  "twitter" : {
    "settings": {
      "index.number_of_replicas": "1",
      "index.number_of_shards": "1",
      "index.creation_date": "1474389951325",
      "index.uuid": "n6gzFZTgS664GUfx0Xrpjw",
      "index.version.created": ...,
      "index.provided_name" : "twitter"
    }
  }
}

When the flat_settings flag is false, settings are returned in a more human readable structured format:

GET twitter/_settings?flat_settings=false

Returns:

{
  "twitter" : {
    "settings" : {
      "index" : {
        "number_of_replicas": "1",
        "number_of_shards": "1",
        "creation_date": "1474389951325",
        "uuid": "n6gzFZTgS664GUfx0Xrpjw",
        "version": {
          "created": ...
        },
        "provided_name" : "twitter"
      }
    }
  }
}

By default flat_settings is set to false.

Parameters

Rest parameters (when using HTTP, map to HTTP URL parameters) follow the convention of using underscore casing.

Boolean Values

All REST API parameters (both request parameters and JSON body) support providing boolean "false" as the value false and boolean "true" as the value true. All other values will raise an error.

Number Values

All REST APIs support providing numbered parameters as string on top of supporting the native JSON number types.

Time units

Whenever durations need to be specified, e.g. for a timeout parameter, the duration must specify the unit, like 2d for 2 days. The supported units are:

Byte size units

Whenever the byte size of data needs to be specified, e.g. when setting a buffer size parameter, the value must specify the unit, like 10kb for 10 kilobytes. Note that these units use powers of 1024, so 1kb means 1024 bytes. The supported units are:

Unit-less quantities

Unit-less quantities means that they don’t have a "unit" like "bytes" or "Hertz" or "meter" or "long tonne".

If one of these quantities is large we’ll print it out like 10m for 10,000,000 or 7k for 7,000. We’ll still print 87 when we mean 87 though. These are the supported multipliers:

Distance Units

Wherever distances need to be specified, such as the distance parameter in the Geo Distance Query), the default unit is meters if none is specified. Distances can be specified in other units, such as "1km" or "2mi" (2 miles).

The full list of units is listed below:

Fuzziness

Some queries and APIs support parameters to allow inexact fuzzy matching, using the fuzziness parameter.

When querying text or keyword fields, fuzziness is interpreted as a Levenshtein Edit Distance — the number of one character changes that need to be made to one string to make it the same as another string.

The fuzziness parameter can be specified as:

Enabling stack traces

By default when a request returns an error Elasticsearch doesn’t include the stack trace of the error. You can enable that behavior by setting the error_trace url parameter to true. For example, by default when you send an invalid size parameter to the _search API:

POST /twitter/_search?size=surprise_me

The response looks like:

{
  "error" : {
    "root_cause" : [
      {
        "type" : "illegal_argument_exception",
        "reason" : "Failed to parse int parameter [size] with value [surprise_me]"
      }
    ],
    "type" : "illegal_argument_exception",
    "reason" : "Failed to parse int parameter [size] with value [surprise_me]",
    "caused_by" : {
      "type" : "number_format_exception",
      "reason" : "For input string: \"surprise_me\""
    }
  },
  "status" : 400
}

But if you set error_trace=true:

POST /twitter/_search?size=surprise_me&error_trace=true

The response looks like:

{
  "error": {
    "root_cause": [
      {
        "type": "illegal_argument_exception",
        "reason": "Failed to parse int parameter [size] with value [surprise_me]",
        "stack_trace": "Failed to parse int parameter [size] with value [surprise_me]]; nested: IllegalArgumentException..."
      }
    ],
    "type": "illegal_argument_exception",
    "reason": "Failed to parse int parameter [size] with value [surprise_me]",
    "stack_trace": "java.lang.IllegalArgumentException: Failed to parse int parameter [size] with value [surprise_me]\n    at org.elasticsearch.rest.RestRequest.paramAsInt(RestRequest.java:175)...",
    "caused_by": {
      "type": "number_format_exception",
      "reason": "For input string: \"surprise_me\"",
      "stack_trace": "java.lang.NumberFormatException: For input string: \"surprise_me\"\n    at java.lang.NumberFormatException.forInputString(NumberFormatException.java:65)..."
    }
  },
  "status": 400
}

Request body in query string

For libraries that don’t accept a request body for non-POST requests, you can pass the request body as the source query string parameter instead. When using this method, the source_content_type parameter should also be passed with a media type value that indicates the format of the source, such as application/json.

Content-Type Requirements

The type of the content sent in a request body must be specified using the Content-Type header. The value of this header must map to one of the supported formats that the API supports. Most APIs support JSON, YAML, CBOR, and SMILE. The bulk and multi-search APIs support NDJSON, JSON, and SMILE; other types will result in an error response.

Additionally, when using the source query string parameter, the content type must be specified using the source_content_type query string parameter.