On 2011-11-20 15:00, Jon Nelson wrote:
Do you happen to recall if disk I/O is counted as user or system time?
Neither, traditionally. Those times are cpu times; they only account for what the cpu was doing. The disks could be working in parallel as a result of cpu actions, and probably were - but the software found work to do for the cpu. You'd want to be looking at iostat during the run to see how busy the disks were. As to why it takes 16 hours cpu to do the external version but only 34 minutes for internal - some of that will be down to data-shuffling in- and out- of disk files which is nonetheless accounted to user-mode cpu time, but some will be the plain inefficiency of the external version having to effectively do work over many times because it can't have a complete view of the problem at hand at any one time. -- Jeremy -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
