Re: BDB btree vs. BDB hash format

On Fri, Jul 08, 2005 at 01:55:34PM -0400, Brian Burton wrote:
> Thomas Schürger wrote:
> >what is the main motivation for SpamProbe to use BDB btree format
> >instead of BDB hash format? The tree structure of the btree format
> >doesn't seem to be required or exploited somewhere (except that
> >exports are output in sorted order), so the BDB hash format should
> >suffice. It shouldn't have the typical btree problems like removed
> >keys whose allocated space is rarely re-used later. Performance should
> >be better, too.
...
> 
> As I recall I went through a progression as follows:
> 
>  GDBM - horrible performance when database grew, no sorting
>  BDB hash - performance not much better IIRC, no sorting
>  BDB btree - good performance - terms sorted

  I've also found that BDB btree outperforms hash for speed, despite
documentation that suggests otherwise.  Experimenters on the Postfix
mailing list have reported the same.
  -- Clifton

-- 
          Clifton Royston  --  cliftonr-uqdcwbVN1zuHdZQakrT3ElaTQe2KTcn/@public.gmane.org 
         Tiki Technologies Lead Programmer/Software Architect
  "My own personal theory is that this is the very dawn of the world.
We're hardly more than an eyeblink away from the fall of Troy, and
scarcely an interglaciation removed from the Altamira cave painters. We
live in extremely interesting ancient times.
  I like this idea. It encourages us to be earnest and ingenious and
brave, as befits ancestral peoples; but keeps us from deciding that
because we don't know all the answers, they must be unknowable and thus
unprofitable to pursue."  -- Teresa Nielsen Hayden, 1995 


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