# Query historical asset property values in AWS IoT SiteWise
<a name="historical-values"></a>

You can use the AWS IoT SiteWise API [GetAssetPropertyValueHistory](https://docs.aws.amazon.com/iot-sitewise/latest/APIReference/API_GetAssetPropertyValueHistory.html) operation to query the historical values of an asset property.

To identify an asset property, specify one of the following:
+ The `assetId` and `propertyId` of the asset property that data is sent to.
+ The `propertyAlias`, which is a data stream alias (for example, `/company/windfarm/3/turbine/7/temperature`). To use this option, you must first set your asset property's alias. To set property aliases, see [Manage data streams for AWS IoT SiteWise](manage-data-streams.md).

Pass the following parameters to refine your results:
+ `startDate` – The exclusive start of the range from which to query historical data, expressed in seconds in Unix epoch time.
+ `endDate` – The inclusive end of the range from which to query historical data, expressed in seconds in Unix epoch time.
+ `maxResults` – The maximum number of results to return in one request. Defaults to `20` results.
+ `nextToken` – A pagination token returned from a previous call of this operation.
+ `timeOrdering` – The ordering to apply to the returned values: `ASCENDING` or `DESCENDING`.
+ `qualities` – The quality to filter results by: `GOOD`, `BAD`, or `UNCERTAIN`.

**To query the value history for an asset property (AWS CLI)**

1. Run the following command to get the value history for the asset property. This command queries the property's history over a specific 10 minute interval. Replace {{asset-id}} with the ID of the asset and {{property-id}} with the ID of the property. Replace the date parameters with the interval to query.

   ```
   aws iotsitewise get-asset-property-value-history \
     --asset-id {{asset-id}} \
     --property-id {{property-id}} \
     --start-date {{1575216000}} \
     --end-date {{1575216600}}
   ```

   The operation returns a response that contains the historical TQVs of the property in the following format:

   ```
   {
     "assetPropertyValueHistory": [
       {
         "value": {
           "booleanValue": {{Boolean}},
           "doubleValue": {{Number}},
           "integerValue": {{Number}},
           "stringValue": "{{String}}",
           "nullValue": {
               "valueType": "{{String}}"
           }
         },
         "timestamp": {
           "timeInSeconds": {{Number}},
           "offsetInNanos": {{Number}}
         },
         "quality": "{{String}}"
       }
     ],
     "nextToken": "{{String}}"
   }
   ```

1. If more value entries exist, you can pass the pagination token from the `nextToken` field to a subsequent call to the [GetAssetPropertyValueHistory](https://docs.aws.amazon.com/iot-sitewise/latest/APIReference/API_GetAssetPropertyValueHistory.html) operation.