I was reading the above mentioned article by Jonathan Lewis. I do not understand how the number of branch blocks was calculated. So far as I know, the branch blocks have pointers to the leaf blocks. The branch blocks have rowids and range of key values of leaf blocks. I tried to find out more about the structure of branch blocks, but was told not to be concerned about it. Can anyone please clarify how the branch block sizes were calculated.

Thanks...

10,000,000 rows at 100 rows per block => 100,000 leaf blocks 100,000 leaf blocks (at 50 percent packing) => 1,000 level 1 branch blocks 1,000 level 1 branch blocks (at 50 percent packing) => 10 level 2 branch blocks 10 level 2 branch blocks (at 50 percent packing) => 1 level 3 branch block

-- Arun Gupta (c-agupta@state.pa.us), November 24, 2003