[pgpool-general: 1554] Re: pgpool 3.2.3 node gets down after some hours of work.

Dzmitry dzmitry.nikitsin at gmail.com
Fri Mar 29 10:00:01 JST 2013

I don't see any network latency and we are not sending a lot of data. I
don't know how big is delay in replication, but delay exists - it's how
streaming replication works.
If  I do almost simultaneous 2 sql query, one to write data, second - read
written data. Does pgpool handle this situation and do write/read from
master DB(if yes - does delay is configurable?) ? Or it can write to
master and read from slave - when data is not synchronized.


On 3/29/13 3:53 AM, "Lonni J Friedman" <netllama at gmail.com> wrote:

>I think you're trying to solve the wrong problem.   Something seems
>wrong in your environment if there's a non-trivial delay in
>replication between the master & standby.  Is the standby struggling
>to keep up with the changes, or is there a lot of network latency, or
>is there some other problem?
>On Thu, Mar 28, 2013 at 4:48 PM, Dzmitry <dzmitry.nikitsin at gmail.com>
>> I installed & configured pgpool using this guide
>> http://www.pgpool.net/pgpool-web/contrib_docs/simple_sr_setting2_3.0/ .
>> But I found issue with log - you made me thinking, thank you. The issue
>> was I haven't /usr/sbin/rotatelogs2 but I have /usr/sbin/rotatelogs.
>> I will monitor log to check why my node goes down.
>> One more question - my production application is connected to pgpool &
>> do load balancing. When application write data - pgpool send queries to
>> master DB & master do streaming replication with delay. But application
>> can do read very quickly - and pgpool can send query to standy DB where
>> changes is not synchronized yet.(for example user signup: 1 signup, 2 -
>> show protected page - here data can be not synchronized). Is it possible
>> to resolve this situation with pgpool somehow ? Does it have option to
>> send query to specified DB ? Or I need to connect my production
>> application server to master DB directly, but servers that do background
>> processing - can be connected to pgpool ?
>> Thanks,
>>   Dzmitry
>> On 3/29/13 2:24 AM, "Lonni J Friedman" <netllama at gmail.com> wrote:
>>>On Thu, Mar 28, 2013 at 4:10 PM, Dzmitry <dzmitry.nikitsin at gmail.com>
>>>> Dear all,
>>>> I am using postgres 9.2 with streaming replication. I have 1 master DB
>>>> 2 standby DBs, it's hosted on amazon EC2, each has it's own server. On
>>>> separate server i have pgpool(3.2.3) that do load balancing(in pgpool
>>>> config i have num_init_children=290, max_pool- 2, child_life_time -
>>>> 0child_max_connections - 100, connection_life_time- 100,
>>>> - 0. do not cache onnections.). Sometimes pgpool show server status as
>>>> "down", but actually server is up & running fine, due to this, i am
>>>> getting a lot of issues.
>>>> Also i have in pgpool config:
>>>> health_check_timeout - 60
>>>> health_check_period - 30
>>>> health_check_max_retries - 3
>>>> health_check_retry_delay -5
>>>> Also pgpool is not writing log :(
>>>> i setup it
>>>> log_destination "stderr"
>>>> debug_level 0
>>>> logdir /var/tmp - i checked permissions it has 777, so it's not the
>>>> when i start pgpool i start it with "-n" option to let it write log.
>>>> Any ideas why server shown as down & where is my logs ?
>>>Your logs would indicate why the nodes are down.  As for where they
>>>are, you'd have to tell us.  How did you install & configure pgpool?
>L. Friedman                                    netllama at gmail.com
>LlamaLand                       https://netllama.linux-sxs.org

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