B-树的性质 1.Every node x has the following attributes: a.x.n,the number of keys currently stored in nodex, b.the x.n keys themselves,x.key,x.key2,....x.keyx.n,stored in nondecreas- ing order,so thatx.key1≤x.key2≤…≤x.keyx.m c.x.leaf,a boolean value that is TRUE if x is a leaf and FALSE if x is an internal node. 2.Each internal node x also contains x.n+1 pointers x.c1,x.c2,....x.Cx.n+1 to its children.Leaf nodes have no children,and so their ci attributes are unde- fined. 3.The keys x.key;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.key1≤k2≤x.key2≤…≤x.keyx.n≤kx.n+1·B-树的性质