How do I use entity framework with hierarchical data?

Question

I'm working with a large hierarchical data set in sql server - modelled using the standard "EntityID, ParentID" kind of approach. There are about 25,000 nodes in the whole tree.

I often need to access subtrees of the tree, and then access related data that hangs off the nodes of the subtree. I built a data access layer a few years ago based on table-valued functions, using recursive queries to fetch an arbitrary subtree, given the root node of the subtree.

I'm thinking of using Entity Framework, but I can't see how to query hierarchical data like this. AFAIK there is no recursive querying in Linq, and I can't expose a TVF in my entity data model.

Is the only solution to keep using stored procs? Has anyone else solved this?

Clarification: By 25,000 nodes in the tree I'm referring to the size of the hierarchical dataset, not to anything to do with objects or the Entity Framework.

Answer 1

It may the best to use a pattern called "Nested Set", which allows you to get an arbitrary subtree within one query. This is especially useful if the nodes aren't manipulated very often: Managing hierarchical data in MySQL.

In a perfect world the entity framework would provide possibilities to save and query data using this data pattern.