Hey Derek,
I've been playing around with this nested set stuff today - it's
pretty cool. I nearly have an app working that uses the db for page
content and maps the urls out however you want, it's pretty neat.
I have a slight HQL problem with subquery's but I'll post that 2mro :-)
Thanks for all your help
Tim
Sent from my iPhone
On 30 Nov 2008, at 23:37, "Derek Chen-Becker" <[EMAIL PROTECTED]>
wrote:
> IIRC, JPA has support for batch updates, but I'm not 100% positive
> on that. I'll have more time tomorrow to look at this if you'd still
> like to discuss it.
>
> Derek
>
> On Sun, Nov 30, 2008 at 12:32 PM, Tim Perrett <[EMAIL PROTECTED]>
> wrote:
>
> Derek,
>
> Those links are *extremely* good - thank you! I've not really done
> anything with tree structures before and they are really, really
> usefull.
>
> One thing however, it appears the optimal way of doing the insert
> queries would be with stored procedures, however that im not down
> with, and ideally, i want to keep database vendor independent (part of
> the point of using JPA) so ideally i want to suck that up into the
> application logic. For instance:
>
> --START
> SELECT @myRight := rgt FROM nested_category WHERE name =
> 'TELEVISIONS';
>
> UPDATE nested_category SET rgt = rgt + 2 WHERE rgt > @myRight;
> UPDATE nested_category SET lft = lft + 2 WHERE lft > @myRight;
>
> INSERT INTO nested_category(name, lft, rgt) VALUES('GAME CONSOLES',
> @myRight + 1, @myRight + 2);
> --END
>
> This makes use of variables, and i could of course do this via 3
> separate queries in JPA, but i wondered if there was a neater way to
> construct this type of thing with JPA?
>
> Any advice you guys have is most welcome
>
> Cheers
>
> Tim
>
>
> On Nov 30, 2:27 pm, "Derek Chen-Becker" <[EMAIL PROTECTED]> wrote:
> > If you're heavily skewed towards reads and not writes (as it seems
> in the
> > case of a CMS), you might want to look at Celko nested sets:
> >
> > http://www.intelligententerprise.com/001020/celko.jhtml
> > http://dev.mysql.com/tech-resources/articles/hierarchical-data.html
> >
> > A little more work on updates than an adjacency model, but a lot
> more
> > efficient.
> >
> > Derek
>
>
>
>
> >
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