SPARQL Results serialization and parsing is slow with large result sets
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Key: JENA-178
URL: https://issues.apache.org/jira/browse/JENA-178
Project: Jena
Issue Type: Bug
Components: ARQ
Affects Versions: ARQ 2.8.9
Environment: Windows 7 Enterprise 64 bit
Reporter: Rob Vesse
The SPARQL XML and JSON Result formats are very slow when the result set is
large. This is surprising to me since both formats are relatively simple and
should lend themselves to fairly fast streaming serialization and parsing.
The following are observed performance figures comparing SPARQL XML, SPARQL
JSON and SPARQL TSV results format. This is the averaged time over 5 runs to
retrieve the first 50,000 triples from the dataset with a simple SELECT * WHERE
{ ?s ?p ?o } LIMIT 50000 via a HTTP request to Fuseki and iterate over the
results on the client.
SPARQL XML = 15.25 seconds
SPARQL JSON = 10.9 seconds
SPARQL TSV = 0.54 seconds
Now obviously TSV is way simpler to serialize and parse than XML/JSON but these
serializers and parsers should not be 20-30 times slower IMO
Also for comparison note that doing an equivalent CONSTRUCT { ?s ?p ?p } WHERE
{ ?s ?p ?o } LIMIT 50000 takes only about 2s and that is using RDF/XML
serialization which I would have expected to be slower because RDF/XML is more
complex to generate than either SPARQL XML/JSON results. I haven't dived into
the code in detail to investigate why this is slow yet but do the Jena team
have any thoughts on this?
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