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sanket pathre avatar image
sanket pathre asked

HierarchyID needed Help

I have read many articles about HierarchyID

http://msdn.microsoft.com/en-us/library/bb677290.aspx

In above link I found, hierarchy ID take the size is about 6*logAn bits, where A is the average fan-out. Can anybody give me definition of fan out. Is fan out for current level in which you are adding new node or is it considering all node in hierarchy.

For eg

If "A" has two child "B" and "C". "B" and "C" also has 2 children each "D", "E" and "F", "G" respectively.

what is average fan out of "A". Total there are 7 nodes. A,B,C has 2 child each then average fan out is 6/7 OR just 2 as there is no other node in same hierarchy level of A.

Also please forward me any article which has measure performance of heirarchyID Db Type.

Up to How many node I can stored as child of root node. That is just up to one hierarchical level. I.e. I want to find One root node and X child nodes. What will be the max value of X.

hierarchical-queryhierarchyid
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graz avatar image
graz answered

The article you linked to says that fan out is the average number of children per node. Fan out is the average over the entire hierarchy.

In your example I believe the average fan out would be 2. Each node has two children on average.

I'm not aware of any in depth articles on performance.

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