Re: btree vs hash for ldbm backend

[Mark Blackman <mark@exonetric.com>]

On 25 Jan 2004, at 20:56, Howard Chu wrote:

> > -----Original Message-----
> > From: owner-openldap-software@OpenLDAP.org
> > [mailto:owner-openldap-software@OpenLDAP.org]On Behalf Of Mark 
> > Blackman
>
> > Hi,
> >
> > I just wondered if there was some reason to prefer btree storage
> > ldbm backends over hash storage ldbm backends. Naively, I'd have
> > thought that hash backends would be quicker for lookups, but perhaps
> > there's other issues I'm not considering.
> >
> > In my small dataset (~1000 entries), I can't find any difference in
> > speed between the two, but I'd guess for large datasets there is a
> > noticeable difference.
> >
> > Anyway, I'd be grateful for the merest clue why btree appears
> > to be preferred.
>
> http://www.sleepycat.com/docs/ref/am_conf/select.html

Thanks. That was something I think I read ages ago and
came to the conclusion that for unknown datasets and unknown
applications, hash was preferred as there was not a huge
difference between best and worst case, where btree performance
is very sensitive to lookup order.

Anyway, thanks for reminding me of the good discussion there.

I believe that for my apps and datasets, hash is to be preferred.

Cheers,
Mark
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