Thank you Kingsley,
Is there an approximate date for the patch?
Thank you,
Best/Cordialement,
Charbel El Kaed, PhD
Business Architect
Digital Services Platform
Global Solutions
Schneider Electric
D +1 (978) 975-9361 x59361
M +1 (978) 289-3190
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From: Kingsley Idehen [mailto:kide...@openlinksw.com]
Sent: Thursday, November 03, 2016 9:30 PM
To: virtuoso-users@lists.sourceforge.net
Subject: Re: [Virtuoso-users] Query performance with R2RML remote RDBMS SQL
Server
On 10/14/16 12:41 PM, CHARBEL EL KAED wrote:
Hello,
I would like to have your opinion on the following:
I installed Virtuoso Enterprise on a Windows VM with:
8 cores
28 GB RAM
56 GB SSD
I attached virtuoso configuration file.
On virtuoso I have a local RDF Table with 8221 triples and a remote MS SQL
Azure with 50 million records. A record is simply an id, param1 and param2,
with (id and param1) as a composite primary key.
I have the following query:
Select ?id ?param1 ?param2 {
Select ?id ?param1 ?param2 FROM
<http://localhost:8890/sqldb50m#<http://localhost:8890/sqldb50m>>
Where {
[] <http://localhost:8890/schemas/sqldb50m/id> ?id;
<http://localhost:8890/schemas/ sqldb50m
/param1<http://localhost:8890/schemas/%20sqldb50m%20/param1>> ? param1;
<http://localhost:8890/schemas/ sqldb50m /param2
<http://localhost:8890/schemas/%20sqldb50m%20/param2%20> > ? param2.
filter (?param1 < 5)
{
SELECT DISTINCT (strafter(str(?id1), "#") AS ?trimId) from
<http://localhost:8890/BOC#<http://localhost:8890/BOC>>
WHERE
{
?server qt:hasId ?id1. //returns 42 ids
}
}
filter( ?trimId = ?id)
}
};
The query is expected to return 1 million record result.
I initiated the query yesterday through iSQL, it is still running since, more
than 12 hours. On the Windows VM, the task manager shows that Virtuoso consumes
10 GB of RAM and less then 5% of CPU.
On the MS SQL monitoring tool, you can notice the load is constant using only
10% of the CPU and 10% of the DTU.
Any recommendations to improve the performance?
Thank you
There should be an update in your support case about this matter.
Fundamentally, there was a SPARQL Optimizer bug that lead to the shared
variable effect not kicking in i.e., executing the remote part of the query.
Here are examples to explain the gist of the matter:
## Problematic due to missing {} around dataset modifier fragments that
contain shared variables between local and remote
## Data Sources
SELECT ?s ?p (sql:BEST_LANGMATCH (?o, "ru, en-gb;q=0.8, en;q=0.7, *;q=0.1",
"")) as ?o_filtered
WHERE {
?s a foaf:Person .
# Virtuoso Extension for setting Named Graph scope on a Remote SPARQL
service
SERVICE <http://dbpedia.org/sparql><http://dbpedia.org/sparql> from
<http://dbpedia.org><http://dbpedia.org>
{
?s ?p ?o .
FILTER (?p !=
<http://dbpedia.org/property/abstract><http://dbpedia.org/property/abstract>)
}
OPTIONAL { ?p rdfs:label ?lbl }
}
ORDER BY ASC (COUNT (?o))
## Revised query using {} to group dataset modifier fragments to set scope for
shared variable identifiers
SELECT ?s ?p (sql:BEST_LANGMATCH (?o, "ru, en-gb;q=0.8, en;q=0.7, *;q=0.1",
"")) as ?o_filtered
WHERE {
{ ## shared variable block start ##
?s a foaf:Person .
# Virtuoso Extension for setting Named Graph scope on a Remote
SPARQL service
SERVICE <http://dbpedia.org/sparql><http://dbpedia.org/sparql> from
<http://dbpedia.org><http://dbpedia.org>
{
?s ?p ?o .
FILTER (?p !=
<http://dbpedia.org/property/abstract><http://dbpedia.org/property/abstract>)
}
## shared variable block end ## }
OPTIONAL { ?p rdfs:label ?lbl }
}
ORDER BY ASC (COUNT (?o))
## Another example that failed where I am passing values using BIND. This
failed and will work properly when the fix is in ##
PREFIX
