Virtuoso performance

counts don't seem to be reliable

Action Item:
A new custom header is being added for this scenario (it will be live by
the time you read this mail), so as to provide additional information to
this situation. Basically, X-MaxRows: {ini-hard-limit-value}, which in
this case would be 10,000. Note the maximum is 2,000,000 for Virtuoso.

Virtuoso Diagnostics for Query Optimization


Virtuoso 22023 Error SR...: The result vector is too large #119

Graphs names

ld_dir('/usr/local/virtuoso-opensource/var/lib/virtuoso/db', 'extraction_output.nt', 'http://ontosides/missing');




Answered on the Virtuoso Users mailing list where the question was also asked... Dumping results in various formats can be done by using the define output:format "{XX}" pragma, so in your case it would be: SQL> sparql define output:format "TURTLE" CONSTRUCT ... Other possible formats are: NICE_TTL RDF_XML etc. When using the ISQL client to fetch long texts, use the set blobs on; directive to avoid receiving a data truncated warning. i.e.: SQL> set blobs on; SQL> sparql define output:format ... For CONSTRUCT, the supported formats are: TRIG, TTL, JSON, JSON;TALIS, SOAP, RDF/XML, NT, RDFA;XHTML, JSON;RES, HTML;MICRODATA, HTML, JS, ATOM;XML, JSON;ODATA, XML, CXML;QRCODE, CXML, HTML;UL, HTML;TR, JSON;LD, CSV, TSV, NICE_TTL, HTML;NICE_MICRODATA, HTML;SCRIPT_LD_JSON, HTML;SCRIPT_TTL, HTML;NICE_TTL


isql 1111 errors=stdout test.out
isql 1111 dba dba VERBOSE=OFF 'EXEC=status()' test.sql test2.sql -i arg1 arg2

SPARQL query limiting results to 100000 triples

Prevent Limits of Sorted LIMIT/OFFSET query

SELECT ?p ?s
          ?s ?p 
        } ORDER BY ASC(?p)
OFFSET 50000
LIMIT 1000

RAID 10 vs Virtuoso striping. What is the best for IO performance?

Backward chaining


Efficient Use of SQL - SQL Execution profiling

profile ('SELECT COUNT (*) from ct_c a, ct_c b WHERE a.k2 = b.k1 option (loop, order)');


CPU load goes up to 100% when Virtuoso runs its look up processing

Virtuoso.ini param

How to Update Large SPARQL Data avoiding due to database checkpoint abortion?

Translate and Analyze modes for analyzing sparql queries

The “MaxQueryCostEstimationTime"param should never be set in the INI file

Compiling and configuring Virtuoso

Upgrading to the latest Virtuoso git develop/7 branch which is a 07.20.3219

Returns statistics for a running server as a result set


Virtuoso 7 typically requires 10GB RAM per billion triples,

What is the storage cost per triple?

Virtuoso.ini settings parameters

Performance diagnostics

IO Bound

Configuring Virtuoso for Scale

Performance Tuning Virtuoso for RDF Queries by using RDF indexes