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symfony1doctrinenested-setsadjacency-list

Doctrine nested set vs adjacency list

I need to display a tree of categories by levels (all tree elements on each level).

Root
Cat1 (parent_id) Cat2 (parent_id) ...
Subcat1 (parent_id) Subcat2 (parent_id) Subcat3 (parent_id) ...

I tried to implement it with Nested Set structure, but I ran into a problem: no easy way to get the parent's node id (without a separate query to the database). Should I use Adjacency list instead?

The goal is to make the display as fast as possible, ideally with one query to the database.

Solution

  • Read this article about Nested Set vs Adjacency List. You'll see that Nested Set makes the queries faaaaar easier to write. Also read this § about the nested set hierarchy hydration method, and you'll figure out how to get several doctrine objects in a hierarchical form with a single query.