2.3.2 BTree-on-Heap (BTH)
A BTree-on-Heap implements a classic BTree on a heap node. A BTH consists of several parts: A header, the BTree records, and optional BTree data. The following diagram shows a high-level schematic of a BTH.
The preceding diagram shows a BTH with two levels of indices. The top-level index (Key, HID) value pairs actually point to heap items that contain the Level 1 Indices, which, in turn, point to heap items that contain the leaf (Key, data) value pairs. Each of the six boxes in the diagram actually represents six separate items allocated out of the same HN, as indicated by their associated HIDs.