[Monetdb-developers] Will optimisations occur in storage when indexing is applied?

Niels Nes Niels.Nes at cwi.nl
Fri Aug 22 08:51:09 CEST 2008

On Fri, Aug 22, 2008 at 03:42:40AM +0200, Stefan de Konink wrote:
> Hi,
> If a user places an index on a varchar column will the actual character 
> storage move to an intermediate (or final) column with only unique 
> instances of each string. Or will the storage in the original table 
> definition still contain all materialized string, instead of pointers to 
> the index?
There are 2 indices in monetdb. The prime purpose are to speed up
primary and foreign key checks. Both only store numbers (hash values and
oid's for the primary-foreing key relation). So we cannot reduce the 
varchar storage in this case.

However the primary storage of varchar's does allready do this 
duplicate elimination and only stores pointers too strings.

> Stefan
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Niels Nes, Centre for Mathematics and Computer Science (CWI)
Kruislaan 413, 1098 SJ Amsterdam, The Netherlands
room C0.02,  phone ++31 20 592-4098, fax ++31 20 592-4312
url: http://www.cwi.nl/~niels   e-mail: Niels.Nes at cwi.nl

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