Re: contrib/tree issues

On Wed, 29 May 2002 achill(at)matrix(dot)gatewaynet(dot)com wrote:

>
> I have been playing with the tree package, and so far
> it seems fast.
>
> But i have some questions:
>
> How can we find "maximum" direct child of a node?
>
> e.g.
> The table has as:
>
> dynatree=# SELECT node from achtree ;
> node
> -------
> 1
> 2
> 1.1
> 1.1.1
> 1.2
> (5 rows)
>
> dynatree=#
>
> Now we find the children of '1' of level 2:
>
> dynatree=# SELECT node from achtree where node <* '1.*.0';
> node
> ------
> 1.1
> 1.2
> (2 rows)
>
> dynatree=#
>
> Now if we want to insert another level 2 child of '1',
> how can we get the current maximum value of level 2 children of node '1'??
> (in this case 2), so that we can insert '1.3' to the table???

Just use functions entree_next(entree), bitree_next(bitree) -
return next free node.

>
> Also, i want to ask if somebody has extended postgresql's jdbc
> implemantation to include support for bitrees,entrees.
>
> One maybe slow solution for both of the above would be to
> be able to cast e.g. entree to text, so that
>
> a) taking the lexicographically maximum bitree value would give the
> maximum current child, and
> b) java intergration would be trivial through java.lang.String.
>
> Thanx
>
>
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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