Tom Lane wrote:
Robert Haas <robertmh...@gmail.com> writes:
On Wed, Sep 22, 2010 at 1:09 PM, Joshua D. Drake <j...@commandprompt.com> wrote:
On Wed, 2010-09-22 at 13:00 -0400, Robert Haas wrote:
But it CAN'T be a system catalog, because, among other problems, that
rules out cascading slaves, which are a feature a lot of people
probably want to eventually have.
I guarantee you there is a way around the cascade slave problem.

And that would be...?

Indeed.  If it's a catalog then it has to be exactly the same on the
master and every slave; which is probably a constraint we don't want
for numerous reasons, not only cascade arrangements.
It might be an idea to store the replication information outside of all clusters involved in the replication, to not depend on any failure of the master or any of the slaves. We've been using Apache's zookeeper http://hadoop.apache.org/zookeeper/ to keep track of configuration-like knowledge that must be distributed over a number of servers. While Zookeeper itself is probably not fit (java) to use in core Postgres to keep track of configuration information, what it provides seems like the perfect solution, especially group membership and a replicated directory-like database (with per directory node a value).

regards,
Yeb Havinga



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