Обсуждение: Upgrading and streaming replication
I'm planning my upgrade from 9.1.5 to 9.1.6 on some master and streaming-replication standby pairs and have some questions: Generally: http://www.postgresql.org/docs/9.1/static/warm-standby.html section 25.2.1 says: "...it is likely that running different minor release levels on primary and standby servers will work successfully. However, no formal support for that is offered and you are advised to keep primary and standby servers at the same release level as much as possible. When updating to a new minor release, the safest policy is to update the standby servers first — a new minor release is more likely to be able to read WAL files from a previous minor release than vice versa." My mental translation of this is "...try updating the standby first and hope it works - if not and you at some point find your standby is scrod, you're on your own...we warned you..." Is this the correct interpretation? I'd feel better if there were a documented approved upgrade process for systems using streaming replication and that the release notes would specify when a minor upgrade involves WAL file changes that require special handling (and it would be nice if PostgreSQL would detect dangerous format mismatch issues and refuse to start). Specifically: Neither the update release notes on the wiki (http://wiki.postgresql.org/wiki/20120924updaterelease as of this writing) nor the release notes http://www.postgresql.org/docs/9.1/static/release-9-1-6.html nor news http://www.postgresql.org/about/news/1416/ indicate that any special handling is required on standby servers. Can anyone confirm if that is correct or, if not, what additional steps are prudent? Cheers, Steve
Hi, On Tue, 2012-09-25 at 14:22 -0700, Steve Crawford wrote: > "...it is likely that running different minor release levels on > primary > and standby servers will work successfully. However, no formal > support > for that is offered and you are advised to keep primary and standby > servers at the same release level as much as possible. When updating > to > a new minor release, the safest policy is to update the standby > servers > first — a new minor release is more likely to be able to read WAL > files > from a previous minor release than vice versa." > > My mental translation of this is "...try updating the standby first > and hope it works - if not and you at some point find your standby is > scrod, you're on your own...we warned you..." I would translate it as: "Newer minor releases will be compatible with the previous versions, so receving xlogs from older releases will be supported. Upgrade standby first, and then the master server" Regards, -- Devrim GÜNDÜZ Principal Systems Engineer @ EnterpriseDB: http://www.enterprisedb.com PostgreSQL Danışmanı/Consultant, Red Hat Certified Engineer Community: devrim~PostgreSQL.org, devrim.gunduz~linux.org.tr http://www.gunduz.org Twitter: http://twitter.com/devrimgunduz