On 31.08.2020 14:06, Dirk Krautschick wrote:
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.
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Regards,
Maksim Milyutin