Peter Ansell wrote:
Thanks,
I will try that out.
I am using the HTTP sparql interface so I will see how it goes with
the define.
Peter,
The pragmas as part of Virtuoso SPARQL, so the work fine via SPARQL
endpoint using SPARQL protocol.
Kingsley
Peter
*From:* Hugh Williams <[email protected]>
*To:* Peter Ansell <[email protected]>
*Cc:* Yves Raimond <[email protected]>;
[email protected]
*Sent:* Friday, 19 June, 2009 9:20:23 AM
*Subject:* Re: [Virtuoso-devel] Deadlocking and slow queries
Peter,
On 18 Jun 2009, at 23:38, Peter Ansell wrote:
Hi all,
----- Original Message ----
From: Yves Raimond <[email protected]
<mailto:[email protected]>>
To: [email protected]
<mailto:[email protected]>
Sent: Thursday, 18 June, 2009 9:57:51 PM
Subject: [Virtuoso-devel] Deadlocking and slow queries
Another major issue we're running into is the deadlocking mechanism.
We have a constant flow of updates going in through
SPARQL/Update. Our
dataset is a collection of fairly small graphs (around 30 triples
each). When we do a query like the above, going through all these
graphs, we're almost sure to reach a deadlock at some point. At
almost
any point in time, there is an update going on in one of the graphs.
I have been having this issue too as I am fairly constantly
running SPARQL INSERT's on a single graph and intermittently
asking the graph for results. It would be nice to have a
consistent solution if possible even if the read-only query is
postponed for a second to allow the concurrent insert to run its
course. None of the inserts are very large (30 or so triples
each), so it is a little strange that the two queries needed to
interfere with each other. I have five indexes on the RDF_QUAD
table btw if that interferes with things. (RDF_QUAD_GPOS
RDF_QUAD_OGPS RDF_QUAD_OPGS RDF_QUAD_POGS RDF_QUAD_SPOG)
The whole database actually silently locked up at one point and
stopped INSERT's working at all when I was experimenting with
CLEAR'ing the graph while INSERT's were happening, but I
restarted it and haven't tried the same thing again so I can't
say whether it was a consistent bug. You might be able to test
some concurrent CLEAR GRAPH queries along with consistent
INSERT's (every second or so)and see if the lockup happens in a
test scenario.
The inserts are some experimental statistics gathering based on
Bio2RDF queries that I thought would be cool and I want to
periodically check the progress without stopping the statistics
gathering process.
[Hugh] When perform SPARUL inserts/updaes/deletes you should use
the log_enable(2) function in you client to force the query to
autocommit and release all locks immediately as detailed at:
http://docs.openlinksw.com/virtuoso/rdfperformancetuning.html#rdfperfsparul
http://docs.openlinksw.com/virtuoso/fn_log_enable.html
Note if you are querying directly against SPARQL endpoint you will
need to pass the the following pragma to set log_enable(2) for
each query:
define sql:log-enable 2
This resolved Yves's problem which was discussed on the
"openlink-virtuoso" IRC ...
Best Regards
Hugh Williams
OpenLink Software
Cheers,
Peter
Access Yahoo!7 Mail on your mobile. Anytime. Anywhere.
Show me how: http://au.mobile.yahoo.com/mail
------------------------------------------------------------------------------
Crystal Reports - New Free Runtime and 30 Day Trial
Check out the new simplified licensing option that enables unlimited
royalty-free distribution of the report engine for externally facing
server and web deployment.
http://p.sf.net/sfu/businessobjects
_______________________________________________
Virtuoso-devel mailing list
[email protected]
<mailto:[email protected]>
https://lists.sourceforge.net/lists/listinfo/virtuoso-devel
------------------------------------------------------------------------
Access Yahoo!7 Mail on your mobile. Anytime. Anywhere. Show me how
<http://au.rd.yahoo.com/mail/mobile/tagline/*http://au.mobile.yahoo.com/mail>.
------------------------------------------------------------------------
------------------------------------------------------------------------------
Crystal Reports - New Free Runtime and 30 Day Trial
Check out the new simplified licensing option that enables unlimited
royalty-free distribution of the report engine for externally facing
server and web deployment.
http://p.sf.net/sfu/businessobjects
------------------------------------------------------------------------
_______________________________________________
Virtuoso-devel mailing list
[email protected]
https://lists.sourceforge.net/lists/listinfo/virtuoso-devel
--
Regards,
Kingsley Idehen Weblog: http://www.openlinksw.com/blog/~kidehen
President & CEO
OpenLink Software Web: http://www.openlinksw.com
