Re: High Availability, guarantee to use sync nodes

Maksim Milyutin <milyutinma@xxxxxxxxx> · Tue, 1 Sep 2020 20:10:41 +0300



    On 31.08.2020 14:06, Dirk Krautschick wrote:

    
        Hi all,
      
    
    Hi

    
        if there are several
            PostgreSQL nodes replicating synchronous and I configure a
            guarantee that
        for example 3 of 5 nodes
            have to be in sync to go on with synchronous_standby_names
            and
            
        now I want to implement
            a load balancing scenario with active standby DBs…how or
            with what
        tool can I achieve that
            my read clients only use sync nodes. For sure somehow a
            check in the
        pg_stat_replication
            before is possible but is there something in parameters or
            with solutions
        like repmgr, patroni,
            etc. to do this?
      
    
    For such tools as patroni or stolon the list of sync replicas
      could be got from DCS storage (etcd, consul, etc). Your
      application or some proxy, e.g. haproxy with confd, might extract
      the list of sync nodes, subscribe on changes in KV entry that
      stores this list and routes queries according it.

    
    -- 
Regards,
Maksim Milyutin