Giving monetdb a fair chance

Stefan Manegold Stefan.Manegold at cwi.nl
Thu Jul 11 11:53:46 CEST 2013


Hi Franck,

thanks for the feedback!

Which version of MonetDB are you using?

Which OS are you using?

Did you install a pre-built binary version of MonetDB, or are did you compile it yourself from sources (HG or released tarball?)?
If the latter, which configure options did you use?

And, as Martin suggested, would you be able to share your database schema, queries, and possibly even data with us (or at least some more data characteristic)?

Alternatively, could you profile the behavior using Stetoscope (as Martin suggests) or by simply prefixing your SQL queries with TRACE and share the (performance/profiling-) results?

Thanks!
Stefan

----- Original Message -----
> Hi
> 
> Without insight into your benchmark queries and database schema for
> the row stores, little can be said.
> A typical pitfall could be to use row-based queries such as "SELECT *
> FROM tableexpr", which would call
> for expensive tuple reconstruction of all columns. Another
> explanation can come from a multidimensional
> index maintained in a rowstore to speedup grouping. Last but not
> least, it could be grouping order or
> skewed data distribution.
> 
> MonetDB provides some tools to see where time goes, which may give a
> hint.
> http://www.monetdb.org/Documentation/Manuals/MonetDB/Profiler/Stethoscope
> 
> Your table sizes reported is not extreme at all.
> 
> regards, Martin
> 
> On 7/11/13 10:47 AM, Franck Routier wrote:
> > Hi,
> >
> > I am benchmarking different DB alternatives for our BI application.
> > We are using Mondrian/JPivot on a dataset with ~300 millions row,
> > and several parent/child dimensions.
> >
> > We are running some 50 real life scenario (ie 50 differents cubes
> > using parts of this dataset) and measuring user response time on a
> > server with several stripped Sata3 SSD, 32 GB ram and a i7-3820
> > CPU @ 3.60GHz (6 cores).
> >
> > During the tests, Monetdb performed by far the worst of Postgresql,
> > VectorWise and (obvioulsy) MonetDB.
> > Things that take 10 seconds with Postgresql take 450 second with
> > monetdb...
> > This was not expected at all, so looking at the server, I saw that
> > MonetDB was consuming all memory (why not), including swap : bad
> > idea I think. I was expecting MonetDB to memory mapped files when
> > needed, real memory, but not use swap as it it was real
> > memory...
> > So here is my question : with a (quite) big dataset, 32GB ram, is
> > there anything I can do to help MonetDB behave according to
> > expectancies ?
> >
> > (maybe I should use ulimit ?).
> >
> > Thanks for your input,
> >
> > Franck
> >
> >
> >
> > _______________________________________________
> > users-list mailing list
> > users-list at monetdb.org
> > http://mail.monetdb.org/mailman/listinfo/users-list
> >
> 
> _______________________________________________
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> 

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