Maybe your server is configured to close idle connections very quickly? The 
MySQL default is 8 hours I believe, and the message you quoted indicates that 
the connection was idle for only 350 seconds. The jdbc:keepAlive value of 3600 
seconds won't help if the server closes the connection after 350 seconds. Maybe 
try a lower value, or increase the timeout setting on the server?

Best,
Richard


On 1 Sep 2011, at 19:59, Zach Schweinfurth wrote:

> Richard,
> 
> I upped the Xmx to 13500m, and that resolved the Unknown Characther error 
> that I was having. However, now I am coming acorss this error: Communications 
> link failure Last packet sent to the server was 350689 ms ago. The query that 
> is giving me the error runs for about five minutes or so, then throws this 
> error. I'm not sure why the communications link between the D2R and the 
> server is going down. 
> 
> I have specified   jdbc:keepAlive "3600" and jdbc:keepAliveQuery "SELECT 1" 
> in my mapping file. 
> 
> Is there something else that I need to do to keep the communications link up?
> 
> Thanks.  
> 
> On Thu, Sep 1, 2011 at 10:13 AM, Zach Schweinfurth 
> <[email protected]> wrote:
> Thanks for the response Richard. 
> 
> I am testing the BSBM at a scale factor of 284826. 
> 
> 
> On Thu, Sep 1, 2011 at 9:24 AM, Richard Cyganiak <[email protected]> wrote:
> Hi Zach,
> 
> Once you get an OutOfMemoryError, pretty much anything can happen… The first 
> thing to try is increasing the -Xmx256M setting in the d2r-server script to 
> assign more heap to the JVM.
> 
> What size of BSBM dataset are you trying?
> 
> Best,
> Richard
> 
> 
> On 31 Aug 2011, at 19:31, Zach Schweinfurth wrote:
> 
> > On other thing to note, this error seems to always occur after I get a java 
> > heap space error. That is, I will run a query, get a java heap space error. 
> > Then any other query I run, I will get the unknown character error.
> >
> > On Wed, Aug 31, 2011 at 11:42 AM, Zach Schweinfurth 
> > <[email protected]> wrote:
> > Hello.
> >
> > I have been working with D2R 0.7 server and the BSBM benchmark relational 
> > data set. And I have come across this error while executing sparql queries 
> > in D2R server against the mappings I have made: Unknown character set index 
> > for field '25959' received from server.:
> >
> > The set up of my mysql database is as follows:
> >
> > I generated sql files from the BSBM generator, loaded them into a mysql 
> > database on mysql server 5.1, running on a virtual Ubuntu 10.04 32 Bit 
> > within my server. All I did to load the database was execute the sql files 
> > that the BSBM generated created. The sql files from the BSBM generator all 
> > seem to set columns and the database itself to a utf8 character set. The 
> > mysql server has its default character set as latin1, but as far as I 
> > understand that character set is not used if the database itself has set a 
> > default character set.
> >
> > The set up of my D2R server is as follows:
> >
> > Running D2R Server version 0.7 on a virtual Ubuntu 10.04 32 Bit within the 
> > same server box the mysql database is running in. I created a mapping file 
> > based on the specification. I connect from D2R server to the mysql 
> > database, both located within my internal network, fine without any mapping 
> > validation errors. Then once I start running queries against the mappings I 
> > get the Unknown character set index for field '25959' received from server 
> > error. Sometimes I am able to get simple limited queries to return results 
> > from the database, but the majority of the queries I run give me the 
> > Character Set error.
> >
> >
> > Do you all happen to know of any possible errors I am making or of any sort 
> > of settings that may be causing this error?
> >
> > Thanks.
> > --
> > Zachary Schweinfurth
> > Ontology Engineer
> > Revelytix, Inc.
> >
> >
> >
> >
> > --
> > Zachary Schweinfurth
> > Ontology Engineer
> > Revelytix, Inc.
> >
> > ------------------------------------------------------------------------------
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> 
> 
> 
> 
> -- 
> Zachary Schweinfurth
> Ontology Engineer
> Revelytix, Inc.
> 
> 
> 
> 
> -- 
> Zachary Schweinfurth
> Ontology Engineer
> Revelytix, Inc.
> 
> ------------------------------------------------------------------------------
> Special Offer -- Download ArcSight Logger for FREE!
> Finally, a world-class log management solution at an even better 
> price-free! And you'll get a free "Love Thy Logs" t-shirt when you
> download Logger. Secure your free ArcSight Logger TODAY!
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> [email protected]
> https://lists.sourceforge.net/lists/listinfo/d2rq-map-devel


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