YES! The new snapshot seems to solve the problem! Queries are lightning fast. Great work. Thanks a lot. :)
On 06/01/2010 12:36 PM, Ivan Mikhailov wrote: > Hello Sebastian, > > Something is really weird with this case, because it works at the local > box. The most important question was whether the database statistics are > calculated correctly (if not then execution plans would be wrong in the > majority of queries). The direct comparison of statistical estimates and > the real content of indexes has proven that statistics are accurate with > factor from 0.5 to 2 for nearly all values, that is quite sufficient for > the optimizer (logarithmic tolerance interval 0.7--1.3 is good enough > when compared with scale from e.g. -3 to +10 ). > > So I still do not know the exact origin of the problem and I should > suspend the investigation for few days. > > Best Regards, > > Ivan Mikhailov > OpenLink Software > http://virtuoso.openlinksw.com > > On Thu, 2010-04-29 at 17:40 +0200, Sebastian Trüg wrote: >> Hello, >> >> using a V6 server with default indexes I would like to know why the >> following queries are different in performance. The store contains >> thousands of different graphs but adding a "graph ?g {}" around all >> patterns does not change the execution time. >> >> select * where { ?r a nfo:FileDataObject . >> ?r nfo:fileName ?f . >> ?f bif:contains 'breaking' . } >> >> takes a long time to finish - almost a minute. >> >> >> select * where { ?r nfo:fileName ?f . >> ?f bif:contains 'breaking' . } >> >> is finished in no time. >> >> I just would like to understand the reasons behind the difference. If >> possible also a solution. :) >> >> Cheers, >> Sebastian >> >> ------------------------------------------------------------------------------ >> _______________________________________________ >> Virtuoso-users mailing list >> [email protected] >> https://lists.sourceforge.net/lists/listinfo/virtuoso-users > >
