Yes Vijaykumar you are right it is just a random shuffle while picking a slave.
Is there a way I can specify in the connection parameters to pick a slave with zero lag else fall back to master?
On Sun, Jun 17, 2018 at 2:11 PM, Vijaykumar Jain <vjain@xxxxxxxxxxxxx> wrote:
I guess the distinction between master and secondary logic can be looked up here(isMaster)
https://github.com/pgjdbc/pgjdbc/blob/ f78a639d1ed3c64e80e1fa107691b4 af5945cb84/pgjdbc/src/main/ java/org/postgresql/core/v3/ ConnectionFactoryImpl.java
and from within slaves iirc we did check the code and it is random shuffle and does not support any custom logic to pick any slaves.
I might be wrong but I do remember looking it up in the source :)
Regards,
Vijay
________________________________________
From: Debraj Manna <subharaj.manna@xxxxxxxxx>
Sent: Sunday, June 17, 2018 11:31:32 AM
To: pgsql-admin
Subject: [External] JDBC Postgres Failover with quorum based synchronous replication
Hi
Let's say I am using quorum based synchronous replication<https://wiki.postgresql.org/wiki/New_in_ > either ANY or FIRST in synchronous_standby_namespostgres_10#Quorum_Commit_for_ Synchronous_Replication
I am trying to read from slave as discussed here<https://jdbc.postgresql.org/documentation/head/ >.connect.html
jdbc:postgresql://node1,node2,node3/accounting? 1. How does a slave is selected? Is a slave randomly selected or a slave is preferred which has zero lag or the minimum lag?targetServerType=preferSlave& loadBalanceHosts=true
Can someone let me know
2. Is there any setting in jdbc url which will only select the slave with zero replication and if no such slave exists then read will be sent to master ?
Thanks,
