[Pkg-postgresql-public] Bug#784005: Bug#784005: postgresql-9.4: Cluster upgrade from 9.1 to 9.4 results in broken configuration

[Christoph Berg]

Control: severity -1 normal
Control: reassign -1 postgresql-common

Re: Gunnar Wolf 2015-05-02 <20150502022312.5656.52842.reportbug at mosca.iiec.unam.mx>
> Now, following the instructions at
> /usr/share/doc/postgresql-common/README.Debian.gz (section "Default
> clusters and upgrading") led to a seemingly correct cluster migration
> — Just at the final step, at the cluster restart time, I got:
> 
> 2015-05-02 01:27:01 GMT FATAL:  could not open shared memory segment "/PostgreSQL.1804289383": Function not implemented

>     dynamic_shared_memory_type = sysv
> 
> As posix semantics seem not to work under LXC (or not under its
> default configuration).

Hi Gunnar,

I'd call it a LXC bug if it doesn't support POSIX shared memory.
That said, I've been bitten by this problem as well - in my case,
/dev/shm was simply not mounted and a cluster with no explicit
dynamic_shared_memory_type setting defaulted to "posix" didn't start.
If you create a new cluster in such an environment, initdb will probe
the various shared memory types and pick one that works. I'm not
really happy with this auto-probing because it hides the real problem,
but atm that's what upstream has designed.

We'll document the gotcha in README.Debian.

Christoph
-- 
cb at df7cb.de | http://www.df7cb.de/