Re: Database system identifier via SELECT?

You can get the database system identifier from the OS shell as part of the
control data:
pg_controldata /Library/PostgreSQL/9.1/data

Here, '/Library/PostgreSQL/9.1/data' is my data directory on os x; replace
it with your own data directory.
>From there, you can isolate the database system identifier with grep:
pg_controldata /Library/PostgreSQL/9.1/data | grep "system identifier"

This is not the same as calling a function within a SELECT statement, but
using the shell command above, one could easily write a function that
returns the database system identifier as a string in a SQL query.

I hope this solves the problem.

On Thu, Dec 8, 2011 at 4:57 PM, Scott Mead <scottm(at)openscg(dot)com> wrote:

>
> On Thu, Dec 8, 2011 at 4:27 PM, Bruce Momjian <bruce(at)momjian(dot)us> wrote:
>
>> Joshua D. Drake wrote:
>> >
>> > On 12/08/2011 12:57 PM, Bruce Momjian wrote:
>> > >
>> > > Chris Redekop wrote:
>> > >> Is there any way to get the database system identifier via a select
>> > >> statement? I have a primary/secondary async replication setup, and
>> I'd
>> > >> like be able to verify from the client side that the provided
>> primary and
>> > >> secondary connection strings do in fact refer to the same data set...
>> > >
>> > > Wow, that is a reasonable thing to want available via SQL, but I can't
>> > > see a way to get to it.
>> > >
>> > > The only method I can suggest is to write a server-side C function
>> that
>> > > calls GetSystemIdentifier().
>>
>
> select inet_server_addr()?
>
> --Scott
>
>
>
>
>> >
>> > This seems like something we should have in core, don't you think?
>>
>> Yeah, kind of, except this is the first request we ever got for this.
>> The identifier is passed as part of streaming replication, so maybe it
>> will be needed more in the future.
>>
>> --
>> Bruce Momjian <bruce(at)momjian(dot)us> http://momjian.us
>> EnterpriseDB http://enterprisedb.com
>>
>> + It's impossible for everything to be true. +
>>
>> --
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>
>