[Xapian-discuss] Speed of range queries

Dmitry Karasik dmitry at karasik.eu.org
Wed Oct 31 09:25:33 GMT 2012

Hi Olly,

Thank you very much for help! I've played with both profiling and logging, and
here's what I found: Execution of the 'slow' case is CPU-bound, but profiling
shows nothing really interesting, same functions are used as in the 'fast'
case. I've rebuilt xaping with logging, and dumped it separately with A,M,E,and
Q log options, and it seems that it's not as much functions themselves are
slow, but the execution plan that is wildly different. Do you think that can be
true?  Anyway, here's the collection of all logs:


xapian.* are debug logs, others are profiler outputs ( I couldn't collect for
D, it coredumps with stack overflow, see xapian.D.coredump ). Most diffence
goes into xapian.*.M.txt, the slow is a small log while the fast one is 47M,
possibly that gives a hint.

Well anyway I'd be glad to find out more, - and thanks for the great product!


> If rebuilding is a pain, you could try profiling the two cases and see
> where the time is spent - that might give enough of a clue to work out
> what is happening.  There are some tips on profiling on the wiki:
> http://trac.xapian.org/wiki/ProfilingXapian
> Cheers,
>     Olly


	Dmitry Karasik

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