Re: [PERFORM] Setting vacuum_freeze_min_age really low

2013-05-23 Thread Josh Berkus
HAndres, > Well. For one you haven't proven that the changed setting actually > improves performance. So the comparison isn't really valid. We will I agree that I haven't proven this yet, but that doesn't make it invalid. Just unproven. I agree that performance testing is necessary ... and the

Re: [PERFORM] Setting vacuum_freeze_min_age really low

2013-05-13 Thread Andres Freund
On 2013-05-13 13:21:54 -0400, Robert Haas wrote: > On Sun, May 12, 2013 at 8:50 AM, Andres Freund wrote: > > [ a response that I entirely agree with ] > > +1 to all that. > It's maybe worth noting that it's probably fairly uncommon for vacuum > to read a page and not dirty it, because if the pag

Re: [PERFORM] Setting vacuum_freeze_min_age really low

2013-05-13 Thread Robert Haas
On Sun, May 12, 2013 at 8:50 AM, Andres Freund wrote: > [ a response that I entirely agree with ] +1 to all that. It's maybe worth noting that it's probably fairly uncommon for vacuum to read a page and not dirty it, because if the page is all-visible, we won't read it. And if it's not all-visi

Re: [PERFORM] Setting vacuum_freeze_min_age really low

2013-05-12 Thread Andres Freund
Hi Josh, On 2013-05-11 16:28:32 -0700, Josh Berkus wrote: > > That, and Tom's concern about forensics, which I understand to be the > > larger sticking point. > > I don't buy the idea that we should cause regular recurring performance > issues for all of our users in order to aid diagnosing the k

Re: [PERFORM] Setting vacuum_freeze_min_age really low

2013-05-11 Thread Josh Berkus
Robert, Andres, > That, and Tom's concern about forensics, which I understand to be the > larger sticking point. I don't buy the idea that we should cause regular recurring performance issues for all of our users in order to aid diagnosing the kind of issues which happen 1% of the time to 2% of o

Re: [PERFORM] Setting vacuum_freeze_min_age really low

2013-05-09 Thread Andres Freund
On 2013-05-09 12:09:04 -0400, Robert Haas wrote: > On Mon, Mar 25, 2013 at 4:31 PM, Josh Berkus wrote: > > In the past, setting vacuum_freeze_min_age (vfma) really low (say to > > 1 or 5) would have caused lots of extra writing work due to > > dirtying extra pages for freezing. This has b

Re: [PERFORM] Setting vacuum_freeze_min_age really low

2013-05-09 Thread Andres Freund
Hi, On 2013-03-25 13:31:17 -0700, Josh Berkus wrote: > In the past, setting vacuum_freeze_min_age (vfma) really low (say to > 1 or 5) would have caused lots of extra writing work due to > dirtying extra pages for freezing. This has been our stated reason to > keep vfma high, despite the o

Re: [PERFORM] Setting vacuum_freeze_min_age really low

2013-05-09 Thread Robert Haas
On Mon, Mar 25, 2013 at 4:31 PM, Josh Berkus wrote: > In the past, setting vacuum_freeze_min_age (vfma) really low (say to > 1 or 5) would have caused lots of extra writing work due to > dirtying extra pages for freezing. This has been our stated reason to > keep vfma high, despite the ob

[PERFORM] Setting vacuum_freeze_min_age really low

2013-03-25 Thread Josh Berkus
Folks, In the past, setting vacuum_freeze_min_age (vfma) really low (say to 1 or 5) would have caused lots of extra writing work due to dirtying extra pages for freezing. This has been our stated reason to keep vfma high, despite the obvious advantage of freezing tuples while they're stil