Date: Wed, 17 Nov 2004 12:00:32 +0200 (EET)
From: Achilleus Mantzios <achill@matrix.gatewaynet.com>
To: Oleg Bartunov <oleg@sai.msu.su>
Cc: Gary Stainburn <gary.stainburn@ringways.co.uk>,
	sad <sad@bankir.ru>, <pgsql-sql@postgresql.org>
Subject: Re: tree structure photo gallery date quiery
In-Reply-To: <Pine.GSO.4.61.0411171102460.9952@ra.sai.msu.su>
Message-ID: <Pine.LNX.4.44.0411171153130.8174-100000@matrix.gatewaynet.com>
MIME-Version: 1.0
Content-Type: TEXT/PLAIN; charset=ISO-8859-7
Content-Transfer-Encoding: 8BIT

O Oleg Bartunov έγραψε στις Nov 17, 2004 :

> Gary,
> 
> if you need really fast solution for you task and dont't afraid
> non-standard soltion, take a look on  contrib/ltree module.
> http://www.sai.msu.su/~megera/postgres/gist/ltree/
> 
>  	Oleg

Oleg how would you compare an ltree solution against a
genealogical approach using intarray??
i.e. store for each node, its path to root,
e.g. path='{4,2,7}'::int4[] where 4 is the id of the father,
2 of the grandfather, and 7 of the root, whereas root has
path is null.
That way we can do really fast queries using ~, have indexes
on level (path length),first (immediate ancestor),last (root)
using C functions that we can easily write and so forth.
I have extensively used this approach with success.
Can you comment on the pros and cons of each? (int[] with intarray vs 
ltree).

Thanx
> _____________________________________________________________
> 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
> 
> ---------------------------(end of broadcast)---------------------------
> TIP 9: the planner will ignore your desire to choose an index scan if your
>       joining column's datatypes do not match
> 

-- 
-Achilleus