get-cardinality¶

Description¶

Returns the approximate count of unique values that match the query.

Requires permission to access the GetCardinality action.

Synopsis¶

  get-cardinality
[--index-name <value>]
--query-string <value>
[--aggregation-field <value>]
[--query-version <value>]
[--cli-input-json | --cli-input-yaml]
[--generate-cli-skeleton <value>]

Options¶

--index-name (string)

The name of the index to search.

--query-string (string)

The search query string.

--aggregation-field (string)

The field to aggregate.

--query-version (string)

The query version.

--cli-input-json | --cli-input-yaml (string) Reads arguments from the JSON string provided. The JSON string follows the format provided by --generate-cli-skeleton. If other arguments are provided on the command line, those values will override the JSON-provided values. It is not possible to pass arbitrary binary values using a JSON-provided value as the string will be taken literally. This may not be specified along with --cli-input-yaml.

--generate-cli-skeleton (string) Prints a JSON skeleton to standard output without sending an API request. If provided with no value or the value input, prints a sample input JSON that can be used as an argument for --cli-input-json. Similarly, if provided yaml-input it will print a sample input YAML that can be used with --cli-input-yaml. If provided with the value output, it validates the command inputs and returns a sample output JSON for that command. The generated JSON skeleton is not stable between versions of the AWS CLI and there are no backwards compatibility guarantees in the JSON skeleton generated.

See ‘aws help’ for descriptions of global parameters.

Examples¶

Note

To use the following examples, you must have the AWS CLI installed and configured. See the Getting started guide in the AWS CLI User Guide for more information.

Unless otherwise stated, all examples have unix-like quotation rules. These examples will need to be adapted to your terminal’s quoting rules. See Using quotation marks with strings in the AWS CLI User Guide .

To return the approximate count of unique values that match the query

You can use the following setup script to create 10 things representing 10 temperature sensors. Each new thing has 3 attributes.

# Bash script. If in other shells, type `bash` before running
Temperatures=(70 71 72 73 74 75 47 97 98 99)
Racks=(Rack1 Rack1 Rack2 Rack2 Rack3 Rack4 Rack5 Rack6 Rack6 Rack6)
IsNormal=(true true true true true true false false false false)
for ((i=0; i<10 ; i++))
do
  thing=$(aws iot create-thing --thing-name "TempSensor$i" --attribute-payload attributes="{temperature=${Temperatures[i]},rackId=${Racks[i]},stateNormal=${IsNormal[i]}}")
  aws iot describe-thing --thing-name "TempSensor$i"
done

Example output of the setup script:

{
    "version": 1,
    "thingName": "TempSensor0",
    "defaultClientId": "TempSensor0",
    "attributes": {
        "rackId": "Rack1",
        "stateNormal": "true",
        "temperature": "70"
    },
    "thingArn": "arn:aws:iot:us-east-1:123456789012:thing/TempSensor0",
    "thingId": "example1-90ab-cdef-fedc-ba987example"
}

The following get-cardinality example queries the 10 sensors created by the setup script and returns the number of racks that have temperature sensors reporting abnormal temperature values. If the temperature value is below 60 or above 80, the temperature sensor is in an abnormal state.

aws iot get-cardinality \
    --aggregation-field "attributes.rackId" \
    --query-string "thingName:TempSensor* AND attributes.stateNormal:false"

Output:

{
    "cardinality": 2
}

For more information, see `Querying for Aggregate Data<https://docs.aws.amazon.com/iot/latest/developerguide/index-aggregate.html>`__ in the AWS IoT Developer Guide.

Output¶

cardinality -> (integer)

The approximate count of unique values that match the query.

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