In this paper we show how dynamic brokering for batch allocation in grids based on bi-dimensional indices can be used in practice in computational grids, with or without knowing the sizes of the jobs. We provide a fast algorithm (with a quadratic complexity) which can be used off-line or even on-line to compute the index tables. We also report numerous simulations providing numerical evidence of the great efficiency of our index routing policy as well as its robustness with respect to parameter changes. The value of information is also assessed by comparing the performance of indexes when the sizes of the jobs are known and when they are not known.