library laravel-nestedset

lianhechx/laravel-nestedset

Nested Set Model for Laravel

This is a Laravel package for working with trees in relational databases., _(*1)

• Theory

What are nested sets?

Nested sets or Nested Set Model is a way to effectively store hierarchical data in a relational table. From wikipedia:, _(*2)

The nested set model is to number the nodes according to a tree traversal, which visits each node twice, assigning numbers in the order of visiting, and at both visits. This leaves two numbers for each node, which are stored as two attributes. Querying becomes inexpensive: hierarchy membership can be tested by comparing these numbers. Updating requires renumbering and is therefore expensive., _(*3)