Thread

1. request for new parameter for disable promote (slave only mode)

   Ioseph Kim <pgsql-kr@postgresql.kr> — 2018-07-27T16:05:40Z

   Hi.
   
   I want to build one master & multi slave environments to use physical replication.
   Slave nodes have low hardware spec, so I changed max_connection server parameters, and try start slave node.
   But I could not start slave nodes, 
   because CheckRequiredParameterValues function (in src/backend/access/transam/xlog.c) reject to set less values then master’s values.
   
   It is maybe, 
   This concept is base on some slave node can be promte master.
   In my enterprise environments, readonly slave nodes are not used as master.
   For High availability of master node, I’m using non shared disk fail over (like using pacemaker),
   Then my slave nodes are used for always readonly nodes.
   
   I suggest that new server parameter is added, such like allow_promote = on|off.
   If allow_promte set off then CheckRequiredParameterValues skip check slave node parameters.
   
   If there is a better plan, it is welcome too.
   
   Regards, ioseph. 
   
   
   
   

2. modify: request for new parameter for disable promote (slave only mode)

   Ioseph Kim <pgsql-kr@postgresql.kr> — 2018-07-28T14:56:36Z

   Sorry, I was misstyped. 
   
   non shared -> shared
   
   On Sat, Jul 28, 2018 at 01:05:40AM +0900, Ioseph Kim wrote:
   > Hi.
   > 
   > I want to build one master & multi slave environments to use physical replication.
   > Slave nodes have low hardware spec, so I changed max_connection server parameters, and try start slave node.
   > But I could not start slave nodes, 
   > because CheckRequiredParameterValues function (in src/backend/access/transam/xlog.c) reject to set less values then master’s values.
   > 
   > It is maybe, 
   > This concept is base on some slave node can be promte master.
   > In my enterprise environments, readonly slave nodes are not used as master.
   > For High availability of master node, I’m using non shared disk fail over (like using pacemaker),
   > Then my slave nodes are used for always readonly nodes.
   > 
   > I suggest that new server parameter is added, such like allow_promote = on|off.
   > If allow_promte set off then CheckRequiredParameterValues skip check slave node parameters.
   > 
   > If there is a better plan, it is welcome too.
   > 
   > Regards, ioseph. 
   > 
   > 
   
   
   

3. Re: request for new parameter for disable promote (slave only mode)

   Robert Haas <robertmhaas@gmail.com> — 2018-07-30T17:10:58Z

   On Fri, Jul 27, 2018 at 12:05 PM, Ioseph Kim <pgsql-kr@postgresql.kr> wrote:
   > I want to build one master & multi slave environments to use physical replication.
   > Slave nodes have low hardware spec, so I changed max_connection server parameters, and try start slave node.
   > But I could not start slave nodes,
   > because CheckRequiredParameterValues function (in src/backend/access/transam/xlog.c) reject to set less values then master’s values.
   >
   > It is maybe,
   > This concept is base on some slave node can be promte master.
   
   No, it's because the machinery that computes MVCC snapshots on slaves
   relies on max_connections being set high enough.
   
   -- 
   Robert Haas
   EnterpriseDB: http://www.enterprisedb.com
   The Enterprise PostgreSQL Company