[pgpool-general: 3516] Node disabled problems

James Sewell james.sewell at lisasoft.com
Mon Mar 16 16:19:19 JST 2015


I am using PGpool on an AWS instance with the following settings:

backend_flag0 = 'ALLOW_TO_FAILOVER'
backend_flag1 = 'ALLOW_TO_FAILOVER'
failover_command = ''
failback_command = ''
fail_over_on_backend_error = off

I am managing failovers from an external product (EDB Enterprise Failover
Manager). This seems to work well most of the time.

Sometimes I get the master node failing because of the AWS network flaking
out on me, this works as expected and I get into the following state:

postgres=# show pool_nodes;
 node_id |   hostname   | port | status | lb_weight |  role
 0       |  | 5432 | 3      | 0.500000  | primary
 1       | | 5432 | 2      | 0.500000  | standby
(2 rows)

My question is, is there any way in PGPool to automatically re-enable the
primary node when it shows up again? If it *really* went down then my EFM
would fail it over (which runs pcp_promote_node) - so I just want it to
enable it when it shows up again. I can't explain why EFM seems to be more
fault tolerant than PGPool - but I'm ignoring that for now.

I tried using DISALLOW_TO_FAILOVER , but this removes any way of disabling
a single node and stops all PGPool access when I stop the standby node.
This won't work for me. I need to be able to perform the following

   - promote a node in PGPool to master (I use pcp_promote_node currently)
   - disable a node in PGPool (I use pcp_detach_node currently)
   - enable a node I have disabled (I use pcp_enable_node currently)
   - Operate on just the master node
   - Operate on just the slave node (read only)

I can't seem to find a way to hit all these and still have a functioning

I'm getting the feeling that maybe I can't get all this from PGPool, but
any help would be appreciated. I'm on PGPool 3.3.1


James Sewell,
PostgreSQL Team Lead / Solutions Architect

 Level 2, 50 Queen St, Melbourne VIC 3000

*P *(+61) 3 8370 8000  *W* www.lisasoft.com  *F *(+61) 3 8370 8099


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