PREFIXES not accepted in Neptune SPARQL update query.

Question

I am getting inconsistent behavior from Neptune when using SPARQL endpoint and the UPDATE parameter

This succeeds:
```
number, ip1:38314, ip2:8182, HTTP_POST, [unknown], [unknown], "HttpObjectAggregator$AggregatedFullHttpRequest(decodeResult: success, version: HTTP/1.1, content: CompositeByteBuf(ridx: 0, widx: 653, cap: 653, components=1)) POST /sparql? HTTP/1.1 Accept-Encoding: identity Host::8182 User-Agent: Python-urllib/3.7 Accept: application/sparql-results+xml, application/rdf+xml Content-Type: application/sparql-update Connection: close content-length: 653", "PREFIX xsd:  PREFIX xml:  PREFIX rdfs:  PREFIX owl:  PREFIX rdf:  INSERT DATA { GRAPH  {  a , owl:NamedIndividual;  'John';  'Snow';  'http://example.com' . } }"
```
While this fails:
```
number2, ip:37738, ip2:8182, HTTP_POST, [unknown], [unknown], "HttpObjectAggregator$AggregatedFullHttpRequest(decodeResult: success, version: HTTP/1.1, content: CompositeByteBuf(ridx: 0, widx: 703, cap: 703, components=1)) POST /sparql? HTTP/1.1 Accept-Encoding: identity Host: :8182 User-Agent: Python-urllib/3.7 Accept: application/sparql-results+xml, application/rdf+xml Content-Type: application/sparql-update Connection: close content-length: 703", "PREFIX xsd:  PREFIX xml:  PREFIX rdfs:  PREFIX owl:  PREFIX rdf:  PREFIX flows:  INSERT DATA { GRAPH  {  a , ;  'John';  'Snow';  'http://example.com' . } }"
```
Adding a single Prefix (whether a unique one such as `PREFIX flows: ` in the example, or even just `PREFIX owl: ` will cause a 400 BAD REQUEST error.

I am running these using rdflib 6.x in python.  The general execution code is:
```
from rdflib.plugins.stores.sparqlstore import SPARQLUpdateStore
from rdflib import Graph

store = SPARQLUpdateStore()
store.open((, ))
ng = Graph(store, identifier="GRAPH_URI")
query = """#optionally put prefix here for testing
INSERT DATA
{
   a , owl:NamedIndividual;
       "John";
       "Snow";
       "http://example.com" .
}"""
```

As far as I can tell from the SPARQL update documentation (https://www.w3.org/TR/sparql11-update/#insert), the prefixes should work.

EDIT: fixed some issues due to copying/anonymization that were not SPARQL compliant.

Answer

The syntax of your second example query is incorrect for a couple of reasons.

See here:

```
.... PREFIX flows:  INSERT DATA { GRAPH  { flows#person--4c49da7e> a  ...
```

1. `` is not a valid Namespace in RDF. Namespaces are IRI's, and as such need to have a ":" character to be valid, for example: ``
2. flows#person--4c49da7e> is neither a full URI enclosed in "<>" or a use of the namespace "flows" as it does not have a ":" following the reference to 'flows.'

A valid query could be:

```
PREFIX xsd:  
PREFIX xml:  
PREFIX rdfs:  
PREFIX owl:  
PREFIX rdf:  
PREFIX flows:  
INSERT DATA { 
    GRAPH  { 
        flows:person--4c49da7e a , 
                                  ; 
                         'John'; 
                         'Snow'; 
                         'http://example.com' . 
                        } 
                        
                } 
```

Answer

Yeah, I apologize.  I was copying the queries over by hand from another computer and manually redacting the neptune logs.  The queries themselves are valid (as they are accepted by Neptune) so any errors are in my transposition.

PREFIXES not accepted in Neptune SPARQL update query.

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