Indexing scheme for flash memory

An index scheme of a flash memory for modifying, inserting or deleting a leaf node is provided to reduce a access time about the flash memory and to lengthen the lifetime of the flash memory by minimizing the number of filled in. Index nodes related to a leaf node and the leaf node are filled in the same page which is identical in mu-tree(e). The index nodes(C, A) which are the parent nodes of the leaf nodes and leaf node(F) is stored in the page(P1). The leaf node(E) and the index nodes(B, A) are stored in the page(P2). The leaf node(D) and index nodes(B, A) are stored in the page(P3). If the leaf node(E) and index nodes(B, A) are stored in the page(P2), the index node(A) becomes invalid since the index node(A) designates the page in which the index nodes(B, C) are stored.