On 09/02/2015 03:56 PM, Bruce Momjian wrote:
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?
Selectivity?
JD
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