As for now, DBaaS is only offered on Virtual Servers. Cloud Cubes may be used in the future as well.
IONOS DBaaS doesn't provide connection pooling. However, you may use a connection pooler (such as pgbouncer) between your application and the database.
Depending on the library you are using, it should be something like:
failed to create DB connection: addr x.x.x.x:5432: connection refused.
The best way to manage connections is to have your application maintain a pool of at least 10-20 connections. It is considered bad practice to have a lot of DB connections. However, letting the user configure max_connections themselves in the future is an option.
Yes, see Connection Limits for more info.
We provide an automated backup within our cloud. If you want to backup to somewhere else, you may use a client-side tool, such as pg_dump.
The number of standby nodes (in addition to primary node) doesn’t really matter. If you have one or ten makes no difference. Synchronous modes are slower in write performance due to the increase in latency for communication between a primary node and a standby node.
If you are receiving an error message Parameter out of bounds: The recovery target time is before the newest basebackup., check the earliestRecoveryTargetTime of your backup. Your target time of the restore needs to be after this timestamp. You can use an earlier earliestRecoveryTargetTime backup for your cluster if you have one.
If the earliestRecoveryTargetTime is missing in your backup, the cluster from where you want to restore wasn't able to do a base backup. This can happen, when you e.g. quickly delete a newly created cluster, since the base backup will be triggered up to a minute after the cluster is available.