Re: Raw vs. Cooked

Hello Mark

Thanks again for your input.

I do realise that db_file_sequential_read signifies a wait for a single block IO and when this event represents a large proportion of a query's resource profile the most appropriate action is to reduce the number of database calls (e.g. logical IOs). Only when the number of LIOs required has been truly reduced to a minimum should we consider making changes to the IO subsystem if a performance problem still exists.

Where my confusion comes in is that the optimal configuration in the paper also exhibits the longest db_file_sequential_read durations. This despite the SQL that is being executed during the test being identical the SQL executed when testing the non-optimal configurations. This has led me to think that the increased throughput afforded by async IO has led to busier disks and longer db_file_sequential_read durations. Do you think this assumption is reasonable? Received on Mon Dec 20 2004 - 03:37:39 CST