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From "Andy Seaborne (Commented) (JIRA)" <>
Subject [jira] [Commented] (JENA-178) SPARQL Results serialization is slow for some formats with large result sets
Date Tue, 27 Dec 2011 12:40:30 GMT


Andy Seaborne commented on JENA-178:

Using and a (8K buffer):

== On the 10th iteration (not checking for newlines)
XMLSAX out took: 275
XMLStax out took: 273
XML out took: 264
XML in took: 490
TSV out took: 124
TSV in took: 315
JSON out took: 580
JSON in took: 732
== On the 10th iteration (checking for newlines)
XMLSAX out took: 338
XMLStax out took: 275
XML out took: 439
XML in took: 462
TSV out took: 187
TSV in took: 324
JSON out took: 760
JSON in took: 773

Checked in (IndentedWriter left checking for in-string newlines for now).
revision 1224902

> SPARQL Results serialization is slow for some formats with large result sets
> ----------------------------------------------------------------------------
>                 Key: JENA-178
>                 URL:
>             Project: Jena
>          Issue Type: Bug
>          Components: ARQ
>    Affects Versions: ARQ 2.9.0
>         Environment: Windows 7 Enterprise 64 bit
>            Reporter: Rob Vesse
>            Assignee: Damian Steer
>             Fix For: ARQ 2.9.1
>         Attachments:, Jena178.patch,,,
> 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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