INDEX TRAVERSALS UTILIZING ALTERNATE IN-MEMORY SEARCH STRUCTURE AND SYSTEM MEMORY COSTING

In searching an index in an original search structure for a database, portion(s) of the index are determined to be stored in a memory in an alternate search structure. The alternate search structure with the portion(s) is created and stored in the memory. The index is searched by traversing the alternate search structure and possibly the original search structure. The alternate search structure may be traversed more efficiently than the original search structure. The number of portions of the index may be a tunable parameter or selected based on a performance improvement/expense ratio. The search of the index begins at the alternate search structure. During traversal of the one or more portions in the alternate search structure, if traversal is to continue at a portion in the original search structure, the identity of this portion is obtained. The traversal is continued at this identified portion in the original search structure.