Re: Slow synchronous logical replication

Hi,

On 2017-10-09 10:37:01 +0300, Konstantin Knizhnik wrote:
> So we have implement sharding - splitting data between several remote tables
> using pg_pathman and postgres_fdw.
> It means that insert or update of parent table cause insert or update of
> some derived partitions which is forwarded by postgres_fdw to the
> correspondent node.
> Number of shards is significantly larger than number of nodes, i.e. for 5
> nodes we have 50 shards. Which means that at each onde we have 10 shards.
> To provide fault tolerance each shard is replicated using logical
> replication to one or more nodes. Right now we considered only redundancy
> level 1 - each shard has only one replica.
> So from each node we establish 10 logical replication channels.

Isn't that part of the pretty fundamental problem? There shouldn't be 10
different replication channels per node. There should be one.

Greetings,

Andres Freund