> Please avoid adding another round trip by using a GUC_REPORTed variable (ParameterStatus entry). If you want to support this libpq failover with >pre-10 servers, you can switch the method of determining the primary based on the server version. But I don't think it's worth supporting older servers > at the price of libpq code complexity.
Currently there is no consensus around this. For now, making this patch to address failover to next primary as similar to JDBC seems sufficient for me.
On next proposal of patch I think we can try to extend as you have proposed
>Please consider supporting "standby" and "prefer_standby" like PgJDBC. They are useful without load balancing when multiple standbys are used for HA.
I think they become more relevant with load-balancing. And, making it usable when we extend this feature to have load-balancing makes sense to me.
> I haven't tracked the progress of logical replication, but will target_server_type be likely to be usable with it? How will target_server_type fit logical > replication?
I tried to check logical replication WIP patch, not very sure how to accomodate same.
