On 14 September 2017 at 08:58, Turbo Fredriksson <turbo@bayour.com> wrote:
I’m the system administrator of our environment in AWS. We’re running a Scala app on there, which accesses a RDS (PostgreSQL) cluster in AWS.
This cluster consists of one master (read/write) and several slaves/replicas (read/only).
All these have a different endpoint to access them. If the master dies, AWS will promote one of the replicas as master automatically (if I understand the documentation correctly), but I’m not sure if it will also update the endpoint. I’m fairly certain it doesn’t.
I thought RDS kept the endpoint the same when one of the replica's dies?
Meaning, the app can no longer access the DB!
There’s two solutions to this:
1) Add all endpoints, after each other, in the config. 2) Add a DNS round-robin entry with all endpoints.
For point one, will the driver only try subsequent endpoints/DBs IF the first fails? As in, no load balancing :(.
The driver doesn't do load balancing.
For point two, my question is (and my developer don’t know and don’t have time to dig into this - he have googled, but have not found a determinate answer) is if the pgsql-jdbc driver can recognise which of these are the master automatically. As in, does it “know” which one it can write to?
Yes, it does know when it connects but if that situation changes it will not be able to figure it out
