Re: How to improve db performance with $7K?

От: Tom Lane
Тема: Re: How to improve db performance with $7K?
Дата: ,
Msg-id: 29785.1113542934@sss.pgh.pa.us
(см: обсуждение, исходный текст)
Ответ на: Re: How to improve db performance with $7K?  (Kevin Brown)
Ответы: Re: How to improve db performance with $7K?  (Kevin Brown)
Список: pgsql-performance

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How to improve db performance with $7K?  (Steve Poe, )
 Re: How to improve db performance with $7K?  (Tom Lane, )
  Re: How to improve db performance with $7K?  (Steve Poe, )
 Re: How to improve db performance with $7K?  (Will LaShell, )
 Re: How to improve db performance with $7K?  ("Joshua D. Drake", )
  Re: How to improve db performance with $7K?  (Steve Poe, )
   Re: How to improve db performance with $7K?  (Bjoern Metzdorf, )
    Re: How to improve db performance with $7K?  (Josh Berkus, )
     Re: How to improve db performance with $7K?  (Steve Poe, )
      Re: How to improve db performance with $7K?  (Cott Lang, )
       Re: How to improve db performance with $7K?  (Steve Poe, )
        Re: How to improve db performance with $7K?  (Cott Lang, )
         Follow-Up: How to improve db performance with $7K?  (Steve Poe, )
          Re: Follow-Up: How to improve db performance with $7K?  (Thomas F.O'Connell, )
           Re: Follow-Up: How to improve db performance with $7K?  (Kevin Brown, )
            Re: Follow-Up: How to improve db performance with $7K?  ("Steinar H. Gunderson", )
            Re: Follow-Up: How to improve db performance with $7K?  (Thomas F.O'Connell, )
          Re: Follow-Up: How to improve db performance with $7K?  (Vivek Khera, )
           Re: Follow-Up: How to improve db performance with $7K?  (Will LaShell, )
     Re: How to improve db performance with $7K?  (Steve Poe, )
    Re: Follow-Up: How to improve db performance with $7K?  (PFC, )
     Re: Follow-Up: How to improve db performance with $7K?  ("Steinar H. Gunderson", )
   Re: How to improve db performance with $7K?  (PFC, )
    Re: How to improve db performance with $7K?  (Dave Cramer, )
     Re: How to improve db performance with $7K?  (Greg Stark, )
     Re: How to improve db performance with $7K?  (Alex Turner, )
      Re: How to improve db performance with $7K?  (Steve Poe, )
       Re: How to improve db performance with $7K?  (Alex Turner, )
        Re: How to improve db performance with $7K?  (Vivek Khera, )
         Re: How to improve db performance with $7K?  (Alex Turner, )
        Re: How to improve db performance with $7K?  (William Yu, )
         Re: How to improve db performance with $7K?  (Alex Turner, )
          Re: How to improve db performance with $7K?  (William Yu, )
           Re: How to improve db performance with $7K?  (Alex Turner, )
            Re: How to improve db performance with $7K?  ("Jim C. Nasby", )
             Re: How to improve db performance with $7K?  (Alex Turner, )
              Re: How to improve db performance with $7K?  (Alex Turner, )
               Re: How to improve db performance with $7K?  (Alex Turner, )
              Re: How to improve db performance with $7K?  (Greg Stark, )
               Re: How to improve db performance with $7K?  (Alex Turner, )
               Re: How to improve db performance with $7K?  (Tom Lane, )
                Re: How to improve db performance with $7K?  (Kevin Brown, )
                 Re: How to improve db performance with $7K?  (Greg Stark, )
                  Re: How to improve db performance with $7K?  (Kevin Brown, )
                   Re: How to improve db performance with $7K?  (Tom Lane, )
                    Re: How to improve db performance with $7K?  (Kevin Brown, )
                     Re: How to improve db performance with $7K?  (Alex Turner, )
                      Re: How to improve db performance with $7K?  (PFC, )
                     Re: How to improve db performance with $7K?  (Tom Lane, )
                      Re: How to improve db performance with $7K?  (Kevin Brown, )
                       Re: How to improve db performance with $7K?  (Tom Lane, )
                        Re: How to improve db performance with $7K?  (Kevin Brown, )
                      Re: How to improve db performance with $7K?  (Greg Stark, )
                     Re: How to improve db performance with $7K?  (Vivek Khera, )
                      Re: How to improve db performance with $7K?  ("Joshua D. Drake", )
                       Re: How to improve db performance with $7K?  (Vivek Khera, )
                      Re: How to improve db performance with $7K?  (Kevin Brown, )
                    Re: How to improve db performance with $7K?  (Matthew Nuzum, )
                     Re: How to improve db performance with $7K?  ("Jim C. Nasby", )
                   Re: How to improve db performance with $7K?  (Rosser Schwarz, )
                    Re: How to improve db performance with $7K?  (Kevin Brown, )
                   Re: How to improve db performance with $7K?  (Greg Stark, )
                   Re: How to improve db performance with $7K?  (Bruce Momjian, )
                    Re: How to improve db performance with $7K?  (Alex Turner, )
                     Re: How to improve db performance with $7K?  (Alvaro Herrera, )
                     Re: How to improve db performance with $7K?  (Bruce Momjian, )
              Re: How to improve db performance with $7K?  ("Douglas J. Trainor", )
               Re: How to improve db performance with $7K?  (, )
                Re: How to improve db performance with $7K?  (Alex Turner, )
                 Re: How to improve db performance with $7K?  (, )
            Re: How to improve db performance with $7K?  ("Douglas J. Trainor", )
            Re: How to improve db performance with $7K?  (PFC, )
             Re: How to improve db performance with $7K?  (Alan Stange, )
    Re: How to improve db performance with $7K?  (Dave Cramer, )
 Re: How to improve db performance with $7K?  ("Alexander Kirpa", )
 Re: How to improve db performance with $7K?  ("Mohan, Ross", )
 Re: How to improve db performance with $7K?  ("Matthew Nuzum", )
  Re: How to improve db performance with $7K?  (Greg Stark, )
   Re: How to improve db performance with $7K?  (PFC, )
  Re: How to improve db performance with $7K?  (Tom Lane, )
 Re: How to improve db performance with $7K?  ("Dave Held", )
 Re: How to improve db performance with $7K?  ("Mohan, Ross", )
  Re: How to improve db performance with $7K?  (Steve Poe, )
   Re: How to improve db performance with $7K?  ("Joshua D. Drake", )
   Re: How to improve db performance with $7K?  (William Yu, )
    Re: How to improve db performance with $7K?  (Greg Stark, )
     Re: How to improve db performance with $7K?  (Alex Turner, )
      Re: How to improve db performance with $7K?  (Greg Stark, )
       Re: How to improve db performance with $7K?  (Alex Turner, )
        Re: How to improve db performance with $7K?  (Jacques Caron, )
         Re: How to improve db performance with $7K?  (Alex Turner, )
          Re: How to improve db performance with $7K?  (Alex Turner, )
           Re: How to improve db performance with $7K?  (Jacques Caron, )
            Re: How to improve db performance with $7K?  (Alex Turner, )
          Re: How to improve db performance with $7K?  (Jacques Caron, )
         Re: How to improve db performance with $7K?  (Greg Stark, )
        Re: How to improve db performance with $7K?  (Alan Stange, )
        Re: How to improve db performance with $7K?  (John A Meinel, )
         Re: How to improve db performance with $7K?  (Alex Turner, )
          Re: How to improve db performance with $7K?  ("Joshua D. Drake", )
           Re: How to improve db performance with $7K?  (Alex Turner, )
        Re: How to improve db performance with $7K?  (Steve Poe, )
         Re: How to improve db performance with $7K?  (Alex Turner, )
     Re: How to improve db performance with $7K?  (Jacques Caron, )
      Re: How to improve db performance with $7K?  ("Jim C. Nasby", )
     Re: How to improve db performance with $7K?  (William Yu, )
 Re: How to improve db performance with $7K?  ("Dave Held", )
 Re: How to improve db performance with $7K?  ("Mohan, Ross", )
 Re: How to improve db performance with $7K?  ("Dave Held", )
  Re: How to improve db performance with $7K?  ("Jim C. Nasby", )
 Re: How to improve db performance with $7K?  ("Mohan, Ross", )
  Re: How to improve db performance with $7K?  ("Jim C. Nasby", )
   Re: How to improve db performance with $7K?  (Alex Turner, )
 Re: How to improve db performance with $7K?  ("Dave Held", )
  Re: How to improve db performance with $7K?  (Alex Turner, )
   Re: How to improve db performance with $7K?  (William Yu, )
 Re: How to improve db performance with $7K?  ("Mohan, Ross", )
  Re: How to improve db performance with $7K?  (Bruce Momjian, )
   Re: How to improve db performance with $7K?  (, )
    Re: How to improve db performance with $7K?  ("Jim C. Nasby", )
     What to do with 6 disks?  (Jeff Frost, )
      Re: What to do with 6 disks?  ("Jim C. Nasby", )
      Re: What to do with 6 disks?  (Josh Berkus, )
       Re: Opteron vs Xeon (Was: What to do with 6 disks?)  (Jeff Frost, )
        Re: Opteron vs Xeon (Was: What to do with 6 disks?)  ("J. Andrew Rogers", )
         Re: Opteron vs Xeon (Was: What to do with 6 disks?)  (Jeff Frost, )
          Re: Opteron vs Xeon (Was: What to do with 6 disks?)  (William Yu, )
        Re: Opteron vs Xeon (Was: What to do with 6 disks?)  (Vivek Khera, )
       Re: What to do with 6 disks?  (Vivek Khera, )
      Re: What to do with 6 disks?  (William Yu, )
 Re: How to improve db performance with $7K?  ("Mohan, Ross", )
  Re: How to improve db performance with $7K?  (Bruce Momjian, )
  Re: How to improve db performance with $7K?  (Dawid Kuroczko, )
 Re: How to improve db performance with $7K?  ("Mohan, Ross", )
 Re: How to improve db performance with $7K?  ("Mohan, Ross", )
 Re: How to improve db performance with $7K?  ("Mohan, Ross", )
 Re: How to improve db performance with $7K?  ("Dave Held", )
 Re: How to improve db performance with $7K?  ("Mohan, Ross", )

Kevin Brown <> writes:
> In the case of pure random reads, you'll end up having to wait an
> average of half of a rotation before beginning the read.

You're assuming the conclusion.  The above is true if the disk is handed
one request at a time by a kernel that doesn't have any low-level timing
information.  If there are multiple random requests on the same track,
the drive has an opportunity to do better than that --- if it's got all
the requests in hand.

            regards, tom lane


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