[pgpool-general: 1386] Re: PgPool 3.2.2 doesn't appear to be load balancing

[Lonni J Friedman]

I think pcp_attach_node is what you want?

On Mon, Feb 11, 2013 at 6:04 PM, David Kerr <web at mr-paradox.net> wrote:
> which reminds me, is there a way to do that w/o restarting the server with -D?
>
> On Feb 11, 2013, at 5:17 PM, web at mr-paradox.net wrote:
>
>> Looks like I had to clear the node status, pgpool thought that my slave node was
>> down.
>>
>> On Mon, Feb 11, 2013 at 03:13:29PM -0800, web at mr-paradox.net wrote:
>> - pgpool-II version 3.2.2 (namameboshi), CentOS
>> -
>> - My configuration is currently like this
>> - master_slave_mode = on             # (change requires restart)
>> - master_slave_sub_mode = 'stream'   # (change requires restart)
>> -
>> - sr_check_period = 10
>> - sr_check_user = 'nobody'
>> - sr_check_password = 'n0b0dy'
>> - delay_threshold = 10000000
>> -
>> - backend_hostname0 = master
>> - backend_port0 = 5432
>> - backend_weight0 = 0
>> - backend_data_directory0 = '/db/pg'
>> - backend_flag0 = 'ALLOW_TO_FAILOVER'
>> -
>> - backend_hostname1 = slave
>> - backend_port1 = 5432
>> - backend_weight1 = 1
>> - backend_data_directory1 = '/db/pg'
>> - backend_flag1 = 'ALLOW_TO_FAILOVER'
>> -
>> - All reads and writes are currently going to the master.
>> -
>> - load_balance_mode = on
>> - ignore_leading_white_space = on
>> - white_function_list = ''
>> - black_function_list = 'currval,lastval,nextval,setval'
>> -
>> - I've read the FAQ:
>> -
>> - > It seems my pgpool-II does not do load balancing. Why?
>> - > First of all, pgpool-II' load balancing is "session base", not "statement base". That means, DB node
>> - > selection for load balancing is decided at the beginning of session. So all SQL statements are sent to the
>> - > same DB node until the session ends.
>> -
>> - To mitigate this I have a low client_idle_limit, since rails will attempt to retain it's own pool.
>> - I'd love an opinion on this.
>> -
>> - > Another point is, whether statement is in an explicit transaction or not. If the statement is in a
>> - > transaction, it will not be load balanced in the replication mode. In pgpool-II 3.0 or later, SELECT will be
>> - > load balanced even in a transaction if operated in the master/slave mode.
>> -
>> - I read this as: in version >3 that I should expect to see SELECTs load balanced in master/slave mode.
>> -
>> - > Note the method to choose DB node is not LRU or some such. Pgpool-II chooses DB node randomly considering
>> - > the "weight" parameter in pgpool.conf. This means that the chosen DB node is not uniformly distributed among
>> - > DB nodes in short term. You might want to inspect the effect of load balancing after ~100 queries have been
>> - > sent.
>> -
>> - I set the weight for the master to 0 in hopes that basically all non-writes go to the slave.
>> -
>> -
>> - Any help would be great, if i can debug, or log anything I'd be happy to do so. (nothing particularly
>> - useful is in the current logs)
>> -
>> - Thanks
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>> pgpool-general at pgpool.net
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>>
>
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L. Friedman                                    netllama at gmail.com
LlamaLand                       https://netllama.linux-sxs.org