On Sun, Nov 20, 2011 at 7:56 AM, Jeremy Harris <jgh@xxxxxxxxxxx> wrote: > On 2011-11-17 17:10, Jon Nelson wrote: >> >> external sort ended, 7708696 disk blocks used: CPU 359.84s/57504.66u >> sec elapsed 58966.76 sec >> >> Am I to understand that the CPU portion of the sorting only took 6 >> minutes but the sort itself took almost 16.5 hours and used approx >> 60GB of disk space? > > > I realise you've had helpful answers by now, but.... that reads > as 16 hours of cpu time to me; mostly user-mode but with 6 minute > of system-mode. 98% cpu usage for the 16 hours elapsed. Thank you very much! I was going to post a followup asking for help interpreting the log line, but now I don't have to. Do you happen to recall if disk I/O is counted as user or system time? If it's counted as system time, then I have more questions, namely: If using a hash table (hash aggregation) shows that the GROUPing can take place in 35 minutes, but a Group Aggregation takes 16 hours, how much of that is CPU and how much is waiting for I/O? -- Jon -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
