Why is vacuum_defer_cleanup_age PGC_USERSET?
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From: Simon Riggs on 3 Jul 2010 14:03 On Sat, 2010-07-03 at 13:07 -0400, Tom Lane wrote: > It seems to me it ought to be PGC_SIGHUP. In the first place, the > actually important value under normal circumstances is going to be > that seen by autovac workers. There is also some impact on HOT > cleanup, but I can't see any sane argument why you don't want all > backends to be applying the same value for that, since it's difficult > or impossible to predict which session is actually going to HOT-clean > any page. In the second place, it seems completely foolish to let > ordinary unprivileged users mess with the value. Arguably an individual > user could produce a denial of service on HS slaves by cutting his local > value of vacuum_defer_cleanup_age and then vacuuming tables that queries > on the slaves will look at. To the extent that the variable does > anything useful at all, it is the system-wide behavior that is > important, so I see no use-case for changing it in individual sessions > anyway. Happy with that argument, so agreed. > It also appears to me to be misclassified. WAL_STANDBY_SERVERS should > be the category for variables that you'd adjust on an HS slave, no? > But this is something that has to be set on the master. Possibly the > best place for it is WAL_REPLICATION. Those didn't exist when it was originally classified, thats all. Yes, those categories sounds good. -- 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
From: Josh Berkus on 7 Jul 2010 17:14
On 7/3/10 10:07 AM, Tom Lane wrote: > It seems to me it ought to be PGC_SIGHUP. +1 I believe it's userset because the other vacuum parameters are, and that nobody thought about it much. -- -- Josh Berkus PostgreSQL Experts Inc. http://www.pgexperts.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 |