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Posted by Jerry Stuckle on 02/07/07 11:29
R. Rajesh Jeba Anbiah wrote:
> On Feb 6, 5:06 pm, Jerry Stuckle <jstuck...@attglobal.net> wrote:
>> R.RajeshJebaAnbiahwrote:
> <snip>
>>> My memory is vain on the theory of the recursive SQL, but the
>>> overhead in nested set architecture is only when you insert the data,
>>> but not while fetching. Usually the categories structure won't change
>>> often--IOW, it's more or less static than dynamic. There is some good
>>> stuff on nested sets here <http://dev.e-taller.net/dbtree/>
>> A side note. The nested set isn't appropriate - and IME it seldom works
>> very in real life. The nested set has its own problems like inserting
>> new items into a large table. It's also more complex to manage than a
>> simple parent/child relationship. I agree with Micha that is is way too
>> complicated for a simple job like this.
>
> As I said earlier, the categories kinda thing for a normal web
> application will be very limited--the table data will be more or less
> static. I'm expecting the table size will be 200-500 records. But,
> when you take the breadcrumb, you have to show it is on every pages--
> the headache is higher here. So, nested set architecture will be ideal
> here or it's variants (my memory recalls two or more variants)
>
Maybe, maybe not. It all depends, doesn't it? And how far down one
goes. I can see this to be a few dozen entries - but I could also
easily see it grow to tens of thousands.
And it may or may not be static. I could also see something which is
fairly dynamic.
>> Hopefully MySQL will get recursive SQL soon. It's quite handy for
>> managing parent-child relationships and other tree types. And it
>> handles other types of relationships as well - including ones where
>> nested sets don't work.
>
> As I said, my memory is vain on the theory of recursive SQL; but I
> still know as I implemented nested sets will be ideal for showing
> breadcrumbs. I'll lurk <news:comp.database.theory> sometime later.
>
> --
> <?php echo 'Just another PHP saint'; ?>
> Email: rrjanbiah-at-Y!com Blog: http://rajeshanbiah.blogspot.com/
>
Try news:comp.database.most.databases.implement.recursive.sql.
Recursive SQL is not theory - it is present in many large databases,
including oracle, sql server and db2. Just not MySQL yet.
I've used the nested set architecture before. It's really a PITA to
manage, and way overkill for something as simple as a parent-child
relationship. And the latter can be easily handled in a stored procedure.
--
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Jerry Stuckle
JDS Computer Training Corp.
jstucklex@attglobal.net
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