Re: Horizontal scalability/sharding

On Wed, Sep  2, 2015 at 02:41:46PM -0400, Robert Haas wrote:
> 4. Therefore, I think that we should instead use logical replication,
> which might be either synchronous or asynchronous.  When you modify
> one copy of the data, that change will then be replicated to all other
> nodes.  If you are OK with eventual consistency, this replication can
> be asynchronous, and nodes that are off-line will catch up when they
> are on-line.  If you are not OK with that, then you must replicate
> synchronously to every node before transaction commit; or at least you
> must replicate synchronously to every node that is currently on-line.
> This presents some challenges: logical decoding currently can't
> replicate transactions that are still in process - replication starts
> when the transaction commits.  Also, we don't have any way for
> synchronous replication to wait for multiple nodes.  But in theory
> those seem like limitations that can be lifted.  Also, the GTM needs
> to be aware that this stuff is happening, or it will DTWT.  That too
> seems like a problem that can be solved.

Can you explain why logical replication is better than binary
replication for this use-case?

--  Bruce Momjian  <bruce@momjian.us>        http://momjian.us EnterpriseDB
http://enterprisedb.com
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