RE: optimizer_index_cost_adj and optimizer_index_cachingIn windows I set DB_FILE_MULTIBLOCK_READ_COUNT to 16 (guy harrison suggestion) which would be the value for MREADTIM in 9i. And which is the complete name for MREADTIM and SREADTIM please. :) According to the Metalink note you can even achieve 8.1.7 behavior when you set MREADTIM = 1.2 * SREADTIM and MBRC=8, but I haven't tested this. And finally I haven't heard for a negative feedback till now and this counts as well. But as usual happens in real life also the system stats is not solving all problems.