Re: BUG #6689: socket file name convention doesn't allow different IPs and the same port for different pgclusters

Hello Magnus,

Thanks a lot for your time checking my email.

Am 15.06.2012 07:56, schrieb Magnus Hagander:
> On Wed, Jun 13, 2012 at 2:45 AM,<ms(at)it-infrastrukturen(dot)org> wrote:
>> The following bug has been logged on the website:
>>
>> Bug reference: 6689
>> Logged by: Mark
>> Email address: ms(at)it-infrastrukturen(dot)org
>> PostgreSQL version: 9.1.3
>> Operating system: unbuntu-server 12.04 LTS
>> Description:
>>
>> When using /var/run/postgresql/ as unix_socket_directory for "main" and
>> "second" pgcluster and different IP-interfaces (addresse) for every
>> pgcluster (but the same default port number), there are different pid file
>> names (like 9.1-main.pid and 9.1-secondpg.pid) *but* names of unix_sockek
>> files doesn't follow such name conventions.
>>
>> It results in error when trying to run the second pgcluster with another IP
>> but the same (default port 5432):
>> Error: Port conflict: another instance is already running on on
>> /var/run/postgresql with port 5432
> First of all, this is not a bug - this is intended behaviour. Perhaps
> the documentation needs to be clearified on the fact that the port
> number needs to be unique across all instances though.
Even it is not an implementation bug it is a kind of *conception* bug
from my point of view.
There is *no* real reason why port numbers should be different for
different IP addresses.

There is anything about running further psql instances on different
ethernet interfaces (on one box) in the current doc yet.

> One reason is that the port number is used to control several other
> things. Just the Unix socket is only one of the things - it also
> controls the name of shared memory segments, so it still won't work if
> you work around that.
When I want to run two separate psql instances they should use also
separate shared memory segments.

> All instances need to have their own ports. If you want to listen on
> the same port on different IPs, you will need to use something like
> kernel level ip forwarding to rewrite the access, and actually run
> PostgreSQL on different ports still.
Using different port number for the second ethernet interface works as
expected.

How complex is it to implement different unix_socket names in the sourse
code?
(when further instances listen on different ethernet interfaces)

regards, Mark

--
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