# Using SPARQL UPDATE UNLOAD to delete data from Neptune
<a name="sparql-api-reference-unload"></a>

Neptune also provides a custom SPARQL operation, `UNLOAD`, for removing data that is specified in a remote source. `UNLOAD` can be regarded as a counterpart to the `LOAD` operation. Its syntax is:

```
UNLOAD SILENT (URL of the remote data to be unloaded) FROM GRAPH (named graph from which to remove the data)
```
+ **`SILENT`**   –   (*Optional*) Causes the operation to return success even if there was an error when processing the data.

  This can be useful when a single transaction contains multiple statements like `"LOAD ...; LOAD ...; UNLOAD ...; LOAD ...;"` and you want the transaction to complete even if some of the remote data could not be processed.
+ *URL of the remote data to be unloaded*   –   (*Required*) Specifies a remote data file containing data to be unloaded from a graph.

  The remote file must have one of the following extensions (these are the same formats that UPDATE-LOAD supports):
  + `.nt` for NTriples.
  + `.nq` for NQuads.
  + `.trig` for Trig.
  + `.rdf` for RDF/XML.
  + `.ttl` for Turtle.
  + `.n3` for N3.
  + `.jsonld` for JSON-LD.

  All the data that this file contains will be removed from your DB cluster by the `UNLOAD` operation.

  Any Amazon S3 authentication must be included in the URL for the data to unload. You can pre-sign an Amazon S3 file and then use the resulting URL to access it securely. For example:

  ```
  aws s3 presign --expires-in (number of seconds) s3://(bucket name)/(path to file of data to unload)
  ```

  Then:

  ```
  curl https://(a Neptune endpoint URL):8182/sparql \
    --data-urlencode 'update=unload (pre-signed URL of the remote Amazon S3 data to be unloaded) \
                             from graph (named graph)'
  ```

  For more information, see [Authenticating Requests: Using Query Parameters](https://docs.aws.amazon.com/AmazonS3/latest/API/sigv4-query-string-auth.html).
+ **`FROM GRAPH `***(named graph from which to remove the data)*   –   (*Optional*) Specifies the named graph from which the remote data should be unloaded.

  Neptune associates every triple with a named graph. You can specify the default named graph using the fallback named-graph URI, `http://aws.amazon.com/neptune/vocab/v01/DefaultNamedGraph`, like this:

  ```
  FROM GRAPH <http://aws.amazon.com/neptune/vocab/v01/DefaultNamedGraph>
  ```

In the same way that `LOAD` corresponds to `INSERT DATA { (inline data) }`, `UNLOAD` corresponds to `DELETE DATA { (inline data) }`. Like `DELETE DATA`, `UNLOAD` does not work on data that contains blank nodes.

For example, if a local web server serves a file named `data.nt` that contains the following 2 triples:

```
<http://example.org/resource#a> <http://example.org/resource#p> <http://example.org/resource#b> .
<http://example.org/resource#a> <http://example.org/resource#p> <http://example.org/resource#c> .
```

The following `UNLOAD` command would delete those two triples from the named graph, `<http://example.org/graph1>`:

```
UNLOAD <http://localhost:80/data.nt> FROM GRAPH <http://example.org/graph1>
```

This would have the same effect as using the following `DELETE DATA` command:

```
DELETE DATA {
  GRAPH <http://example.org/graph1> {
    <http://example.org/resource#a> <http://example.org/resource#p> <http://example.org/resource#b> .
    <http://example.org/resource#a> <http://example.org/resource#p> <http://example.org/resource#c> .
  }
}
```

**Exceptions thrown by the `UNLOAD` command**
+ **`InvalidParameterException`**   –   There were blank nodes in the data. *HTTP status*: 400 Bad Request.

  *Message*: ` Blank nodes are not allowed for UNLOAD`

   
+ **`InvalidParameterException`**   –   There was broken syntax in the data. *HTTP status*: 400 Bad Request.

  *Message*: `Invalid syntax in the specified file.`

   
+ **`UnloadUrlAccessDeniedException `**   –   Access was denied. *HTTP status*: 400 Bad Request.

  *Message*: `Update failure: Endpoint (Neptune endpoint) reported access denied error. Please verify access.`

   
+ **`BadRequestException `**   –   The remote data cannot be retrieved. *HTTP status*: 400 Bad Request.

  *Message*: *(depends on the HTTP response).*