Re: pg_ctl restart - behaviour based on wrong instance

On Sat, Mar 19, 2011 at 10:20 AM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
> On Fri, Mar 18, 2011 at 1:19 PM, Erik Rijkers <er(at)xs4all(dot)nl> wrote:
>> This is OK and expected.  But then it continues (in the logfile) with:
>>
>> FATAL:  lock file "postmaster.pid" already exists
>> HINT:  Is another postmaster (PID 20519) running in data directory
>> "/var/data1/pg_stuff/pg_installations/pgsql.vanilla_1/data"?
>>
>> So, complaints about the *other* instance.  It doesn't happen once a successful start (with pg_ctl
>> start) has happened.
>
> I'm guessing that leftover postmaster.pid contents might be
> responsible for this?

The cause is that "pg_ctl restart" uses the postmaster.opts which was
created in the primary. Since its content was something like
"pg_ctl -D vanilla_1/data", vanilla_1/data/postmaster.pid was checked
wrongly.

The simple workaround is to exclude postmaster.opts from the backup
as well as postmaster.pid. But when postmaster.opts doesn't exist,
"pg_ctl restart" cannot start up the server. We might also need to change
the code of "pg_ctl restart" so that it does just "pg_ctl start" when
postmaster.opts doesn't exist.

Regards,

--
Fujii Masao
NIPPON TELEGRAPH AND TELEPHONE CORPORATION
NTT Open Source Software Center