Re: Pg jdbc DNS failover - Mailing list pgsql-jdbc

From Dave Cramer
Subject Re: Pg jdbc DNS failover
Date
Msg-id CADK3HHLSA2CBWq2S3TSqtUz9ELn2BXkEnWgOvxkb25SKAf087A@mail.gmail.com
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In response to Pg jdbc DNS failover  (Nikolay Prokofiev <nprokofiev@gmail.com>)
List pgsql-jdbc



On Tue, 21 Nov 2023 at 04:07, Nikolay Prokofiev <nprokofiev@gmail.com> wrote:

Hi. According to pgjdbc documantation, the driver supports failover when ip addresses and ports of host are comma separated, like this: jdbc:postgresql://my-db-host-slave-1:5432,my-db-host-master-1:5432/database?targetServerType=primary.

But it's not convenient, because we use k8s for pg, and there may be more slaves added and master ip may be changed.

I want to store all my hosts in DNS and to specify one hostname like this: jdbc:postgresql://my-db-host.local:5432/database?targetServerType=primary

I have a dns record with 2 ip addresses:

$ nslookup my-db-host.local
Server: 192.168.1.1 
Address: 192.168.1.1#53 

Non-authoritative answer:  
Name: my-db-host-slave-1
Address: 192.168.10.21 
Name: my-db-host-master-1
Address: 192.168.11.25

and I tried to specify it like this: jdbc:postgresql://my-db-host.local:5432/database?targetServerType=primary.

But this way it only picks the first ip - slave and fails with org.postgresql.util.PSQLException: Could not find a server with specified targetServerType: primary

Is there any workaround for using dns failover? May be some options in connection pools if driver does not support that?


Currently no.  It would be a useful addition however.

Dave

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