About DBD XML physical storage xml document

Question

Recently I survey about BDB XML,
and I want to know how is it to storage the XML document, what format?? is like Natix storage like in page file ?? So if there are not index can be utilize, the system will use tree travel method to get query answer.
Or there are any document or technical manual support to introduction how DBD XML system internal storage format,how query process, how index build ....etc, because I ready some aboubt document but it major explain how to use the system (like API introduction).
Thanks very much !!

Answer 1

Hi Henry,
The physical nodes store a large amount of information in a record, including it's node ID, it's parent's node ID, it's level in the tree and the node ID of it's last descendant.
Ancestor-descendant relationships can be calculated using the node ID and last descendant ID as upper and lower bounds. Parent-child relationships additionally use the node level information. Sibling relationships need to use the parent's ID to check they have the same parent.
Navigation, on the other hand, uses other node IDs stored in the physical node, or implicit information. For instance if a node has children, it's first child is always the next node record stored. The last child ID is stored in the physical node, since this cannot be similarly calculated, as are the next and previous sibling node IDs.
If you are interested look in dbxml/src/dbxml/nodeStore/NsFormat.(hpp|cpp), which contains the marshaling code for the node storage format.
John