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Re: Berlin SPARQL Benchmark V2 - Results for Sesame, Virtuoso, Jena TDB, D2R Server, and MySQL

From: Story Henry <henry.story@bblfish.net>
Date: Wed, 24 Sep 2008 23:17:03 +0200
Cc: semantic-web@w3.org, "public-lod@w3.org" <public-lod@w3.org>
Message-Id: <778F9A6F-4D38-4EB6-BA1E-66B3352B2A51@bblfish.net>
To: Paul Gearon <gearon@ieee.org>

As a matter of interest, would it be possible to develop RDF stores  
that optimize the layout of the data by analyzing the queries to the  
database? A bit like a Java Just In Time compiler analyses the usage  
of the classes in order to decide how to optimize the compilation.

Henry

On 24 Sep 2008, at 20:30, Paul Gearon wrote:

> A related point is that processing RDF to create an object means you
> have to move around a lot in the graph. This could mean a lot of
> seeking on disk, while an RDBMS will usually find the entire object in
> one place on the disk. And seeks kill performance.
>
> This leads to the operations used to build objects from an RDF store.
> A single object often requires the traversal of several statements,
> where the object of one statement becomes the subject of the next.
> Since the tables are typically represented as
> Subject/Predicate/Object, this means that the main table will be
> "joined" against itself. Even RDBMSs are notorious for not doing this
> efficiently.
Received on Wednesday, 24 September 2008 21:17:47 GMT

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