"Joaquín Mª López Muñoz" wrote: [ random access index used as dynamic index ] The idea is that a sorted random access index can serve as a manual replacement for an ordered index, much like sorted std::vectors are sometimes suggested as an alternative to std::multisets. Random access allows you to efficiently lookup elements with binary search (once the index is sorted, of course.) Colum change can be implemented in a straightforward manner just by appropriately resorting the ra-index. Alas you lose autoupdate --or more precisely, autosort.. --------- This looks as quite useful case for RA index. Perhaps the library may provide something as wrapper around RA index which gets notified when new item is added/removed/updated, throwing exception then. /Pavel