>>> Nor in the tree-based dictionnary, or in the multidimentionnal array. >> No, in an array the unused locations do exist. > I don't understand this. If you have a 2-dimention array > quota[id][type], and quota[class=group] doesn't exist for this > filesytem, you have quota[class=group]=NULL and no memory associated > with it.
Not no memory. The memory for that pointer, the one that's nil, still exists. If you use an array, representing a quota for id=0 and a quota for id=999999 requires 1000000 array elements, even if 999998 of them are nil. With a suitable sparse data structure, the memory cost is..substantially lower. /~\ The ASCII Mouse \ / Ribbon Campaign X Against HTML mo...@rodents-montreal.org / \ Email! 7D C8 61 52 5D E7 2D 39 4E F1 31 3E E8 B3 27 4B
