B-树的性质 1. Every node x has the following attributes a.x. n, the number of keys currently stored in node x, b. the x n keys themselves, x key1, x key2,.,x key x n, stored in nondecreas ing order, so that x:key1≤x.key2≤…≤x.exn, C.x. leaf, a boolean value that is TRUE if x is a leaf and FAlSE if x is an internal 2. Each internal node x also contains x. +I pointers x.C1,xC2, ..,xCx. n+1 to its children. Leaf nodes have no children, and so their ci attributes are unde 3. The keys x key i separate the ranges of keys stored in each subtree: if ki is any key stored in the subtree with root x ci, then k1≤x.1≤k2≤xk2≤…≤x.kxn≤kxB-树的性质