Обсуждение: Running several postmaster using same database in parallel

Hi,

I'am running several postmaster on different machines, accessing the
same database in parallel. Is this a good idea? Do the postmaster lock
each other or do they work independent?

Thanks
    Steffen

Steffen Schmidt writes:

> I'am running several postmaster on different machines, accessing the
> same database in parallel. Is this a good idea?

Not at all.  In fact, version 7.0 and later won't even let you do this any
more.  Earlier versions where not so careful.

--
Peter Eisentraut      peter_e@gmx.net       http://yi.org/peter-e/

On Thu, 23 Nov 2000, Steffen Schmidt wrote:

> I'am running several postmaster on different machines, accessing the
> same database in parallel. Is this a good idea? Do the postmaster lock
> each other or do they work independent?

Are they all accessing the same database on the same machine?  What is the
performance like, as opposed to having a postmaster running on the same
machine as the database and connecting straight via the tcpip?  The
postmaster on the database server still has to be used, doesn't it?

Brett W. McCoy
                                     http://www.chapelperilous.net/~bmccoy/
---------------------------------------------------------------------------
"I'd love to go out with you, but there are important world issues that
need worrying about."

Steffen Schmidt <Steffen.Schmidt@EMBL-Heidelberg.de> writes:
> I'am running several postmaster on different machines, accessing the
> same database in parallel. Is this a good idea? Do the postmaster lock
> each other or do they work independent?

You mean they are all sharing the same data files, using NFS or some
such?  That is a horribly, horribly *bad* idea; I'm surprised you
have not already experienced catastrophic data corruption.  Stop doing
it *at once*, or expect to suffer the consequences :-(

Performance over an NFS mount would be so awful that I don't really
see the point anyway.  Forget the extra postmasters, and just run
one on the machine where the files actually are.

(BTW, what version are you running?  I thought we had an interlock
to check for this sort of silliness --- although perhaps it would
fail to notice a postmaster that wasn't on the same machine ...)

            regards, tom lane

many users have asked for this feature (ie load balancing,clustering, of 1
postgresql database)
but no answer from mailing-list, and no planning for this important feature,
i don't understand why.
Why not set-up a site to found this project with donations... on
postgresql.org?

valter mazzola


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