Re: Optimizing the implementation of an optimized tree

On 7 May 2002, Christian Rishoej wrote:

> On Tue, 2002-05-07 at 04:00, Christopher Kings-Lynne wrote:
>
> > Why not try Oleg and Teodor's tree module?
> >
> > http://cddb.sai.msu.su/~megera/postgres/gist/
> >
> > You have to expend a little effort in implementing it as the README's in
> > Russian :) Still has examples tho.
>
> As far as I can tell Oleg and Teotor are doing *balanced* trees, and not
> trees usable for containing a hiearchy of nodes where each node can have
> 0-N children.
>
> It is my understanding that I cannot rely on the organization of a
> balanced tree - hence the name "balanced" (nodes are inserted where some
> algotithm thinks it fits in, not where I want it. Imagine if your
> directory-hiearchy on your filesystem was a balanced tree...).

Hmm, you decide where to insert new node. It's my fault we don't have
english documentation for our module. But it was designed to work with
catalog like structure. Here is the link to my original posting:
http://fts.postgresql.org/db/mw/msg.html?mid=1352122

Test data (snapshot DMOZ) is available from
http://www.sai.msu.su/~megera/postgres/gist/tree/dmoz-full.sql.gz

There are functions
entree_level(entree) and bitree_level(bitree) which returns next level of
the node. To add node:

select entree_next(tid) from dmoz where tid <* '1.2.3.*.0' order by tid
desc limit 1;

but you're free to add node by hand:

test=# create table tree ( node bitree );
CREATE
test=# insert into tree values ('22.9.15.19.12');
INSERT 41728161 1
est=# select * from tree;
node
---------------
22.9.15.19.12
(1 row)

>
> Does anyone have a clue on how to optimize triggers? Can I use another
> language than PL/PGSQL? Would C be crazy when I do lots of SQL's and no
> calculation in the trigger?
>
> Christian
>
>
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Regards,
Oleg
_____________________________________________________________
Oleg Bartunov, sci.researcher, hostmaster of AstroNet,
Sternberg Astronomical Institute, Moscow University (Russia)
Internet: oleg(at)sai(dot)msu(dot)su, http://www.sai.msu.su/~megera/
phone: +007(095)939-16-83, +007(095)939-23-83