Re: Nested Sets Insertion
Date: Mon, 12 May 2003 20:37:25 GMT
Message-ID: <7f10cvkbpair78e2c4dgdpg385udho9a94_at_4ax.com>
On Mon, 12 May 2003 11:30:40 -0700, "Mikito Harakiri" <mikharakiri_at_ywho.com> wrote:
>"Enu" <ewiner_at_adelphia.net> wrote in message
>news:r1rqbvkskot712c1ll39bdn8upcc411hmp_at_4ax.com...
>> I'm making some forum software using PHP and MySQL that's quite a bit
>> like a Usenet group (i.e. threads). The data won't change much, and
>> the program is very dependent on being able to count the number of
>> descendants of any post (which is very slow with adjacency tables), so
>> I want to use nested sets. Still, for when a post is added directly
>> into the tree, I haven't been able to find any optimized examples of
>> how to do this. I'm sure there's some sort of spiffy mathematical
>> solution of INSERT and UPDATE statements that can append a child to a
>> node and update the left and right values of the affected nodes.
>> Could somebody point me in the right direction? Thanks!
>
>You either use persistent labeling schema, such as materialized path, or
>volatile labeling such as nested sets. Admitedly, with persistent labeling
>schema quering number of children is not as trivial as with nested sets. But
>it is still easy -- it's index range scan! I never saw a thread bigger than
>1000 messages. Comparing to the whole usenet volume it's a pretty selective
>range scan.
>
>They do have indexes in MySQL, do they?-)
>
Received on Mon May 12 2003 - 22:37:25 CEST