what does left_id and right_id in the table forums?

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Discussion of general topics related to the new release and its place in the world. Don't discuss new features, report bugs, ask for support, et cetera. Don't use this to spam for other boards or attack those boards!
frank burian
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what does left_id and right_id in the table forums?

Post by frank burian » Fri Jun 15, 2007 7:57 am

Hey,

can me tell someone for which, the columns "left_id" and "right_id" in the table "forums", it is? and how it builds itself when i insert a forum in the admin panel?

thx, i hope you understand me!?
Frank

frank burian
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Re: what does left_id and right_id in the table forums?

Post by frank burian » Sun Jun 17, 2007 5:26 pm

no answer!

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A_Jelly_Doughnut
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Re: what does left_id and right_id in the table forums?

Post by A_Jelly_Doughnut » Sun Jun 17, 2007 5:27 pm

The two columns constitute a binary tree.
http://en.wikipedia.org/wiki/Binary_tree
A_Jelly_Doughnut

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naderman
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Re: what does left_id and right_id in the table forums?

Post by naderman » Thu Jun 21, 2007 2:15 pm

It's just a general tree and not a binary tree as you can have more then just 2 subforums in a forum ;-) The numbers are necessary to efficiently use a tree stored in a relational database. There's an interesting tutorial explaining the basics on sitepoint: http://www.sitepoint.com/article/hierar ... a-database

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Re: what does left_id and right_id in the table forums?

Post by alcaeus » Thu Jul 05, 2007 8:01 pm

The structure is called a Nested set ;)
It's a special kind of tree: you store the tree in a linear structure (your database) and re-assemble it into a tree in linear time complexity. Of course, completely rebuilding the tree or adding/deleting items is not completely trivial, but since those actions are not done that often, it doesn't matter that much.

Greetz
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god0fgod
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Re: what does left_id and right_id in the table forums?

Post by god0fgod » Tue May 20, 2008 3:45 pm

This was the closest thing to the answer I want. Can anyone please tell me how I would make the numbers for these columns? Does it matter? Thanks for any answers.

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Re: what does left_id and right_id in the table forums?

Post by JRSweets » Tue May 20, 2008 10:51 pm

Did you take a look at the code in the acp to add forum and/or modules?

god0fgod
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Re: what does left_id and right_id in the table forums?

Post by god0fgod » Tue May 20, 2008 11:14 pm

I did look but probably not enough. I'll look again tomorrow.

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the_dan
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Re: what does left_id and right_id in the table forums?

Post by the_dan » Sat May 24, 2008 6:00 pm

The sitepoint article linked above gives details about how the numbers are allocated.

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Dog Cow
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Re: what does left_id and right_id in the table forums?

Post by Dog Cow » Tue May 27, 2008 9:45 pm

They're for sub-forums, right? So you know what the parent forum is, and what the child forum is.

This is my assumption, anyway. :?

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