> http://www.slideshare.net/ibsurgeon/undestandung-firebird-optimizer-by-dmitry-yemanov-in-english
> http://www.slideshare.net/ibsurgeon/firebird-costbased-optimization-and-statistics-by-dmitry-yemanov-in-english
>
> I'm afraid not that much help for newbies without the speakers voice.
>

Thank you very much for your help you've saved me for a full scan web, your b-tree index is much better ! which selectivity :)