Re: why are full table scans good??

It depends on the file system (or RAW or JFS!) you use. Generally the maxio is limited by the kernel constant SSTMAXIO and this is the maximum size (or amont) of data can be read in a single multiblock read. Though you have higher db_file_multiblock_read_count Operating System will not be able to get that much data in a single IO request and will do multiple reads. But your Optimizer will still think it is reading in a single read and may favor FTS over index scan,

I assume your block size is 8k (or 16K or 32K) and I think 8/16 would be the appropriate value if you use UFS or RAW and not tuned the volmaxio kernel parameter. If you have set the MAXIO to non default value you must set your multiblock read count accordingly.

Best Regards,
K Gopalakrishnan
Bangalore, INDIA Received on Wed Dec 05 2001 - 17:10:43 CST