Re: [HACKERS] The case against multixact GUCs

2014-04-16 Thread Josh Berkus
On 03/12/2014 09:45 AM, Heikki Linnakangas wrote: In hindsight, I think permanent multixids in their current form was a mistake. Before 9.3, the thing that made multixids special was that they could just be thrown away at a restart. They didn't need freezing. Now that they do, why not just use

Re: [HACKERS] The case against multixact GUCs

2014-04-16 Thread Andres Freund
On 2014-04-16 11:10:52 -0700, Josh Berkus wrote: On 03/12/2014 09:45 AM, Heikki Linnakangas wrote: In hindsight, I think permanent multixids in their current form was a mistake. Before 9.3, the thing that made multixids special was that they could just be thrown away at a restart. They

Re: [HACKERS] The case against multixact GUCs

2014-04-16 Thread Josh Berkus
On 04/16/2014 11:22 AM, Andres Freund wrote: I'm serious. The multixact stuff has been broken since 9.3 was released, and it's *still* broken. We can't give users any guidance or tools on how to set multixact stuff, and autovacuum doesn't handle it properly. Sorry, but I think you're

Re: [HACKERS] The case against multixact GUCs

2014-04-16 Thread Andres Freund
On 2014-04-16 11:25:49 -0700, Josh Berkus wrote: On 04/16/2014 11:22 AM, Andres Freund wrote: I'm serious. The multixact stuff has been broken since 9.3 was released, and it's *still* broken. We can't give users any guidance or tools on how to set multixact stuff, and autovacuum doesn't

Re: [HACKERS] The case against multixact GUCs

2014-04-16 Thread Josh Berkus
On 04/16/2014 11:30 AM, Andres Freund wrote: On 2014-04-16 11:25:49 -0700, Josh Berkus wrote: On 04/16/2014 11:22 AM, Andres Freund wrote: I'm serious. The multixact stuff has been broken since 9.3 was released, and it's *still* broken. We can't give users any guidance or tools on how to set

Re: [HACKERS] The case against multixact GUCs

2014-03-12 Thread Albe Laurenz
Josh Berkus wrote: What makes these GUCs worse is that nobody knows how to set them; nobody on this list and nobody in the field. Heck, I doubt 1 in 1000 of our users (or 1 in 10 people on this list) know what a multixact *is*. I won't contend your first statement, but multixacts are

Re: [HACKERS] The case against multixact GUCs

2014-03-12 Thread Robert Haas
On Tue, Mar 11, 2014 at 3:14 PM, Josh Berkus j...@agliodbs.com wrote: In the 9.3.3 updates, we added three new GUCs to control multixact freezing. This was an unprecented move in my memory -- I can't recall ever adding a GUC to a minor release which wasn't backwards compatibility for a

Re: [HACKERS] The case against multixact GUCs

2014-03-12 Thread Heikki Linnakangas
On 03/12/2014 06:26 PM, Robert Haas wrote: On Tue, Mar 11, 2014 at 3:14 PM, Josh Berkus j...@agliodbs.com wrote: In the 9.3.3 updates, we added three new GUCs to control multixact freezing. This was an unprecented move in my memory -- I can't recall ever adding a GUC to a minor release which

Re: [HACKERS] The case against multixact GUCs

2014-03-12 Thread Robert Haas
On Wed, Mar 12, 2014 at 12:45 PM, Heikki Linnakangas hlinnakan...@vmware.com wrote: On 03/12/2014 06:26 PM, Robert Haas wrote: On Tue, Mar 11, 2014 at 3:14 PM, Josh Berkus j...@agliodbs.com wrote: In the 9.3.3 updates, we added three new GUCs to control multixact freezing. This was an

Re: [HACKERS] The case against multixact GUCs

2014-03-11 Thread Alvaro Herrera
Sigh ... Josh Berkus wrote: Further, there's no clear justification why these cannot be set to be the same as our other freeze ages (which our users also don't understand), or a constant calculated portion of them, or just a constant. Calculated portion was my first proposal. The objection

Re: [HACKERS] The case against multixact GUCs

2014-03-11 Thread David Johnston
Josh Berkus wrote Hackers, In the 9.3.3 updates, we added three new GUCs to control multixact freezing. This was an unprecented move in my memory -- I can't recall ever adding a GUC to a minor release which wasn't backwards compatibility for a security fix. This was a mistake. It