It seems to me that the question at hand isn't hierarchial entities, per se. 
We have quite a few options for representing them and any will do, 
truthfully.

It is the operations on them which pose issues. Notably, how do we make our 
queries for decendants cost-effective?

I say use whatever representation feels comfortablee to you. Other issues 
you may deal with are a matter of indexing and other operations both 
important and separate from the exact representation. If the need is "give 
me all of this node's decendants" then we may create simple index entries 
mapping a node to each of its decendants and mmay be in a group without 
impacting the nodes themselves or other nodes' decendant indexes.

On Oct 31, 2008 3:21 PM, "Sal" <[EMAIL PROTECTED]> wrote:


Yes, entity groups should be small since 'touching' an entity in the
group/path/hierarchy, blocks the whole group. Entity groups are really
only meant to be used in situations where you need transaction
support. In fact, quoting the GAE documentation, "Only use entity
groups when they are needed for transactions. For other relationships
between entities, use ReferenceProperty properties and Key values".

On Oct 31, 11:23 am, yejun <[EMAIL PROTECTED]> wrote: > I think I have read 
somewhere in documents, ...

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