max_standby_delay considered harmful
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From: Robert Haas on 6 May 2010 00:32 On Wed, May 5, 2010 at 11:50 PM, Bruce Momjian <bruce(a)momjian.us> wrote: > If someone wants to suggest that HS is useless if max_standby_delay > supports only boolean values, I am ready to suggest we remove HS as well > and head to 9.0 because that would suggest that HS itself is going to be > useless. I think HS is going to be a lot less useful than many people think, at least in 9.0. But I think ripping out max_standby_delay will make it worse. > The code will not be thrown away; we will bring it back for 9.1. If that's the case, then taking it out makes no sense. -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise Postgres Company -- Sent via pgsql-hackers mailing list (pgsql-hackers(a)postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
From: Robert Haas on 6 May 2010 00:47 On Wed, May 5, 2010 at 11:52 PM, Bruce Momjian <bruce(a)momjian.us> wrote: > I am afraid the current setting is tempting for users to enable, but > will be so unpredictable that it will tarnish the repuation of HS and > Postgres. We don't want to be thinking in 9 months, "Wow, we shouldn't > have shipped that features. It is causing all kinds of problems." We > have done that before (rarely), and it isn't a good feeling. I am not convinced it will be unpredictable. The only caveats that I've seen so far are: - You need to run ntpd. - Queries will get cancelled like crazy if you're not using steaming replication. That just doesn't sound that bad to me, especially since the proposed alternative is: - Queries will get cancelled like crazy, period. Or else: - Replication can fall infinitely far behind and you can write a tedious and error-prone script to try to prevent it if you like. I think THAT is going to tarnish our reputation. -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise Postgres Company -- Sent via pgsql-hackers mailing list (pgsql-hackers(a)postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
From: Heikki Linnakangas on 6 May 2010 01:35 Robert Haas wrote: > On Wed, May 5, 2010 at 11:52 PM, Bruce Momjian <bruce(a)momjian.us> wrote: >> I am afraid the current setting is tempting for users to enable, but >> will be so unpredictable that it will tarnish the repuation of HS and >> Postgres. We don't want to be thinking in 9 months, "Wow, we shouldn't >> have shipped that features. It is causing all kinds of problems." We >> have done that before (rarely), and it isn't a good feeling. > > I am not convinced it will be unpredictable. The only caveats that > I've seen so far are: > > - You need to run ntpd. > - Queries will get cancelled like crazy if you're not using steaming > replication. And also in situations where the master is idle for a while and then starts doing stuff. That's the most significant source of confusion, IMHO, I wouldn't mind the requirement of ntpd so much. > That just doesn't sound that bad to me, especially since the proposed > alternative is: > > - Queries will get cancelled like crazy, period. > > Or else: > > - Replication can fall infinitely far behind and you can write a > tedious and error-prone script to try to prevent it if you like. > > I think THAT is going to tarnish our reputation. The difference is that that's easy to document and understand, so the behavior won't be a surprise to anyone. -- Heikki Linnakangas EnterpriseDB http://www.enterprisedb.com -- Sent via pgsql-hackers mailing list (pgsql-hackers(a)postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
From: Heikki Linnakangas on 6 May 2010 01:38 Robert Haas wrote: > On Wed, May 5, 2010 at 11:50 PM, Bruce Momjian <bruce(a)momjian.us> wrote: >> The code will not be thrown away; we will bring it back for 9.1. > > If that's the case, then taking it out makes no sense. I doubt we're going to bring back the same code, because it still has the same issues. But we will do something better thought-out. Or people are happy with the boolean and no-one cares anymore, that's pretty likely too. -- Heikki Linnakangas EnterpriseDB http://www.enterprisedb.com -- Sent via pgsql-hackers mailing list (pgsql-hackers(a)postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
From: Simon Riggs on 6 May 2010 00:25
On Wed, 2010-05-05 at 17:56 +0300, Heikki Linnakangas wrote: > Simon Riggs wrote: > > I am mostly unavailable for next few days. (Repairing bikeshed.) > > Hey, you're supposed to do the bikeshedding on-list! ;-) That was just a joke, I'm mostly unavailable for other reasons. -- Simon Riggs www.2ndQuadrant.com -- Sent via pgsql-hackers mailing list (pgsql-hackers(a)postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers |