attribute x 1k the access information of the root access node 50 includes an indicator of the range of values the maximum value in the example shown of the attribute by which the access structure is organized in its child nodes and a pointer to or other identifier of a location of an access node in level 1 in the embodiment shown in fig5 there are five pointers in the root node 50 which point to pages p2 p3 p4 p5 and p6 all in level 1 as indicated by the arrows the access nodes 51 52 53 54 55 in level 1 store a current copy of the statistical information stat rec1 designated sr1 in the figure and a copy of the last promoted version stat rec2 designated sr2 in the figure it can be seen that the number n stored in p1 the root access node 50 is equal to the sum of the values of n 39 stored in the last promoted version sr2 of the statistical information for the access nodes in level 1 thus 79 is equal to the sum of 14 20 15 20 and 10 furthermore the value of the summation s of x 1k stored in the root access node 50 is equal to the sum of the last promoted versions s 39 from sr2 in the access nodes in level 1 each of the access nodes in level 1 includes pointers to data nodes in the figure only the pointers from access node 51 labeled p2 are provided for the purpose of description as can be seen there are four pointers in access node 51 pointing to pages p7 p8 p9 and p10 respectively the statistical information stored in sr1 in the access node 51 is a summary of the statistical.