Re: [HACKERS] MVCC, undo log, and HOT

2007-10-23 Thread Gregory Stark
Andrew Dunstan [EMAIL PROTECTED] writes: HOT is cool, but it really doesn't solve the whole problem. It works for a significant class of problems, but for example it won't have any significant effect on the app I'm currently working on which is very index-rich. It would be a major mistake to

Re: [HACKERS] MVCC, undo log, and HOT

2007-10-23 Thread Simon Riggs
On Mon, 2007-10-22 at 11:00 -0400, Bruce Momjian wrote: Joshua D. Drake wrote: Josh Berkus wrote: Bruce Momjian wrote: Those who have been with the community from long ago might remember discussion about implementing a undo log. The big advantage of this is that it allows UPDATE to

Re: [HACKERS] MVCC, undo log, and HOT

2007-10-23 Thread Jonah H. Harris
On 10/23/07, Simon Riggs [EMAIL PROTECTED] wrote: We never actually considred undo I did, but eventually ruled it out during the HOT design process. But then I considered a ton of other things and ruled them out also. Can't see a reason to bring it up again, so perhaps we should add it to

Re: [HACKERS] MVCC, undo log, and HOT

2007-10-23 Thread Jonah H. Harris
On 10/23/07, Andrew Dunstan [EMAIL PROTECTED] wrote: It would be a major mistake to think there's no work left to do in improving update performance. Agreed. That would be a very short-sighted move. -- Jonah H. Harris, Sr. Software Architect | phone: 732.331.1324 EnterpriseDB Corporation

Re: [HACKERS] MVCC, undo log, and HOT

2007-10-23 Thread Jonah H. Harris
On 10/23/07, Simon Riggs [EMAIL PROTECTED] wrote: Don't *need* would be better. Forgot to mention I agree. What's done is done. I'm not beating that UNDO horse anymore; it's long past dead. -- Jonah H. Harris, Sr. Software Architect | phone: 732.331.1324 EnterpriseDB Corporation

Re: [HACKERS] MVCC, undo log, and HOT

2007-10-23 Thread Joshua D. Drake
On Tue, 23 Oct 2007 09:07:52 -0400 Jonah H. Harris [EMAIL PROTECTED] wrote: On 10/23/07, Andrew Dunstan [EMAIL PROTECTED] wrote: It would be a major mistake to think there's no work left to do in improving update performance. Agreed. That would be a very short-sighted move. I don't

Re: [HACKERS] MVCC, undo log, and HOT

2007-10-22 Thread Bruce Momjian
Joshua D. Drake wrote: Josh Berkus wrote: Bruce Momjian wrote: Those who have been with the community from long ago might remember discussion about implementing a undo log. The big advantage of this is that it allows UPDATE to _replace_ rows and limits the amount of cleanup required

Re: [HACKERS] MVCC, undo log, and HOT

2007-10-22 Thread Josh Berkus
Bruce, We never actually considred undo, but high UPDATE activity was one of the areas we historically handled poorly compared to undo systems, and undo would have been one way to improve that area. I think with HOT we have improved high UPDATE activity enough that the undo benefits are no

Re: [HACKERS] MVCC, undo log, and HOT

2007-10-22 Thread Bruce Momjian
Josh Berkus wrote: Bruce, We never actually considred undo, but high UPDATE activity was one of the areas we historically handled poorly compared to undo systems, and undo would have been one way to improve that area. I think with HOT we have improved high UPDATE activity enough that

Re: [HACKERS] MVCC, undo log, and HOT

2007-10-22 Thread Andrew Dunstan
Bruce Momjian wrote: Josh Berkus wrote: Bruce, We never actually considred undo, but high UPDATE activity was one of the areas we historically handled poorly compared to undo systems, and undo would have been one way to improve that area. I think with HOT we have improved high

Re: [HACKERS] MVCC, undo log, and HOT

2007-10-21 Thread Josh Berkus
Bruce Momjian wrote: Those who have been with the community from long ago might remember discussion about implementing a undo log. The big advantage of this is that it allows UPDATE to _replace_ rows and limits the amount of cleanup required for UPDATEs. I am hoping that with HOT we will no

Re: [HACKERS] MVCC, undo log, and HOT

2007-10-21 Thread Joshua D. Drake
Josh Berkus wrote: Bruce Momjian wrote: Those who have been with the community from long ago might remember discussion about implementing a undo log. The big advantage of this is that it allows UPDATE to _replace_ rows and limits the amount of cleanup required for UPDATEs. I am hoping that

[HACKERS] MVCC, undo log, and HOT

2007-10-20 Thread Bruce Momjian
Those who have been with the community from long ago might remember discussion about implementing a undo log. The big advantage of this is that it allows UPDATE to _replace_ rows and limits the amount of cleanup required for UPDATEs. I am hoping that with HOT we will no longer have any need to