Re: [SQL] How to store directory like structures?

[Oleg Bartunov]

On Sun, 3 Apr 2005, Axel Straschil wrote:

Hello!

I want to store some structure like:

CREATE TABLE node
(
        nodeid  SERIAL PRIMARY KEY,
        parent  INT REFERENCES node(nodeid)
                        ON UPDATE CASCADE ON DELETE CASCADE,
        label   TEXT,
        UNIQUE (parent, label),
        ...
        data
        ...
);

The label is used to map a node to a directory like strukture, so i can
have a function directory_for(nodeid) which gives me
/root_label/parent_label/parent_label/my_label (root labels have NULL as parent)

The problem is the ammount of queries when i've got deep nodes, and I
often have to query if a node is "in path" of another node.

Is there a good solution to build directory-tree like datastruktures?
I found, http://www.sai.msu.su/~megera/postgres/gist/ltree/ which seems
to do what i want, but I've no idea (and probalbly no chance) to get
that running on my system ;-(

what's a problem with ltree ?

Thanks,
AXEL.

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    Regards,
                Oleg
_____________________________________________________________
Oleg Bartunov, sci.researcher, hostmaster of AstroNet,
Sternberg Astronomical Institute, Moscow University (Russia)
Internet: oleg@sai.msu.su, http://www.sai.msu.su/~megera/
phone: +007(095)939-16-83, +007(095)939-23-83

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