[Pgpool-hackers] Proposal: failover control directive

[Tatsuo Ishii]

It seems there's no objection for this.  I am going to add
documentatins, pool_status changes and commit them.
--
Tatsuo Ishii
SRA OSS, Inc. Japan
English: http://www.sraoss.co.jp/index_en.php
Japanese: http://www.sraoss.co.jp

>> Hi pgpool hackers,
>> 
>> I would like to propose new directive to control failover behavior for
>> 3.1.
>> 
>> Background:
>> 
>> Certain configration such as master/slave mode with Slony-I requires
>> master node not to failover. For this purpose the master node is
>> protected by HA(High Availability) software, it is desired for
>> pgpool-II disregard failover event on the master node.
>> 
>> Another use case is, D/W house like configuration with streaming
>> replication. Primary node is not often updated and standby servers are
>> used for load balancing. Sometimes it is not neccessary to promoto a
>> standby when the primary goes down, rather waiting for the primary
>> wakes up.
>> 
>> Proposal:
>> Add new directive to backend_*. to control the failover behavior.
>> 
>> backend_hostname0 = 'example.com'
>> backend_port0 = 5432
>> backend_weight0 = 1
>> backend_flag0 = 'flags' <--- proposed new directive
>> 
>> "flags" can be just a "allow failover or not" for now, but I would
>> like to allow to ORing several flags for the future porpose. At this
>> poing the flag would be:
>> 
>> ALLOW_TO_FAILOVER (allow to failover, default)
>> or
>> NEVER_FAILOVER (do not allow to failover)
>> 
>> Comments?
> 
> Ok, I have created patches for this.
> 
> - Add new directive. If backend_flag0 = 'DISALLOW_TO_FAILOVER'(for
>   example) is specified, no failover (including health checking,
>   connection errors, pcp_detach_node) will happen. If you want to
>   allow failover you can specify backend_flag0 =
>   'ALLOW_TO_FAILOVER'. For backward compatibility sake, if
>   backend_flag0 directive is omitted, it is regarded as backend_flag0
>   = 'ALLOW_TO_FAILOVER' is specified.
> 
> - the directive can only be changed at pgpool starting up.
> 
> - No pool_status patches are included (yet).
> 
> - No documentation patches are included (yet).
> --
> Tatsuo Ishii
> SRA OSS, Inc. Japan
> English: http://www.sraoss.co.jp/index_en.php
> Japanese: http://www.sraoss.co.jp