[pgpool-general: 7316] Re: Setup Pgpool2 with Postgresql Streaming Replication

Nguyen, Tu tnguyen3 at honolulu.gov
Sat Oct 24 16:04:25 JST 2020 

Hi Tatsuo,

Can you tell me exactly which parameters in the "recovery_1st_stage" and "pgpool_remote_start" files I need to replace with my own server information?  I think it may be some settings in there that is causing it to just hang when I run "pcp_recovery_node -h 192.168.94.100 -p 9898 -U postgres"  from the primary server.  It just stalls on the next line and doesn't do anything until I hit Ctrl +C to cancel out of it.  

Should I follow the instructions from this link:  
https://www.pgpool.net/docs/latest/en/html/example-cluster.html

or

This Link:
https://www.pgpool.net/docs/40/en/html/example-cluster.html


Thanks,
Alan

-----Original Message-----
From: Nguyen, Tu 
Sent: Friday, October 23, 2020 12:06 PM
To: 'Tatsuo Ishii' <ishii at sraoss.co.jp>
Cc: pgpool-general at pgpool.net
Subject: RE: Setup Pgpool2 with Postgresql Streaming Replication


Hi all,

Looks like I may have been able to run the pcp_recovery_node command, but after I entered the password, it goes to the next line and just stays there, no errors or anything.  Maybe it's stuck?  I looked on the standby server node I'm trying to recover, with the "top" command and it says CPU usage is around 35% for the pg_basebackup command.  It's been almost 5 hours like this.  Does anyone know how long it takes?  I heard that the standby recovery takes a long time, but does it really take this long?  I have around 15 databases that totals about 300-500 MB of data that Pgpool2 is supposedly trying to recover right now.

Thanks,
Alan

-----Original Message-----
From: Tatsuo Ishii [mailto:ishii at sraoss.co.jp]
Sent: Thursday, October 22, 2020 1:43 AM
To: Nguyen, Tu <tnguyen3 at honolulu.gov>
Cc: pgpool-general at pgpool.net
Subject: Re: Setup Pgpool2 with Postgresql Streaming Replication

> 2020-10-19 10:06:44.941 HST [24277] LOG:  starting PostgreSQL 12.3 
> (Ubuntu 12.3-1.pgdg16.04+1) on x86_64-pc-linux-gnu, compiled by gcc 
> (Ubuntu 5.4.0-6ubuntu1~16.04.12) 5.4.0 20160609, 64-bit

The document is for CentOS, while you are using Ubuntu. I am not sure the documentation is useful for you or not. Anyway...

1) I need the PostgreSQL log while you are getting:

>> I'm at step 7.3.8.1 Set up PostgreSQL standby server:
>> Ran this command on the primary server: pcp_recovery_node -h
>> 192.168.80.90 -p 9898 -U postgres -n 1 And received this error:
>> ERROR:  recovery is checking if postmaster is started
>> DETAIL:  postmaster on hostname:"ltpgsql12" database:"template1"
>> user:"postgres" failed to start in 90 second

2) Do you follow the step "7.3.4. Before Starting"? I am asking because you got this error:

2020-10-19 13:10:23.521 HST [6757] postgres at postgres DETAIL:  User "postgres" has no password assigned.
	Connection matched pg_hba.conf line 8: "host    all             all             0.0.0.0/0               md5"

Have you executed below in the documentation?

  [server1]# psql -U postgres -p 5432
       postgres=# SET password_encryption = 'scram-sha-256';
       postgres=# CREATE ROLE pgpool WITH LOGIN;
       postgres=# CREATE ROLE repl WITH REPLICATION LOGIN;
       postgres=# \password pgpool
       postgres=# \password repl
       postgres=# \password postgres



From: "Nguyen, Tu" <tnguyen3 at honolulu.gov>
Subject: RE: Setup Pgpool2 with Postgresql Streaming Replication
Date: Thu, 22 Oct 2020 09:35:36 +0000
Message-ID: <F152F79048C4864E9825A767687750E404E82E97F0 at CchExMail2.cchnl.hnl>

> Hi Tatsuo,
> 
> Yes I'm using Pgpool-II version 4.0.
> 
> Ssh doesn't seem to be the issue, I was able to test ssh successfully 
> to both servers using this command from the new documentation:  ssh 
> postgres at serverX -i ~/.ssh/id_rsa_pgpool
> 
> I have attached the postgresql-12-main.log file.
> 
> After we get the online recovery task fixed, are there recommended step by step instructions on how to best setup Postgresql Streaming Replication for Pgpool-II 4.0 clustering?  When I execute the "show pool_nodes" command, the replication_state and replication_sync_state values are blank and data is not being replicated.
> 
> On another topic, can the Pgpool2 Connection Pooling feature handle 3,000-4,000 simultaneous connections effectively?
> 
> Thanks,
> Alan
> 
> 
> -----Original Message-----
> From: Tatsuo Ishii [mailto:ishii at sraoss.co.jp]
> Sent: Wednesday, October 21, 2020 10:21 PM
> To: Nguyen, Tu <tnguyen3 at honolulu.gov>
> Cc: pgsql-general at postgresql.org
> Subject: Re: Setup Pgpool2 with Postgresql Streaming Replication
> 
> Hi Alan,
> 
> This is not the best forum to discuss Pgpool-II related topics. I advice you to go to the Pgpool-II dedicated forum:
> 
> https://www.pgpool.net/mailman/listinfo/pgpool-general
> 
>> Hi,
>> 
>> I'm following the steps from:
>> 
>> https://access.crunchydata.com/documentation/pgpool/4.0.0/example-clu
>> s
>> ter.html
> 
> This documentation looks pretty old. The original and the latest documentation for Pgpool-II 4.0 is here (I assume you are using Pgpool-II 4.0):
> 
> 
> 
> 
> https://www.pgpool.net/docs/40/en/html/example-cluster.html
> 
> I strongly suggest to look into this.
> 
>> I'm at step 7.3.8.1 Set up PostgreSQL standby server:
>> Ran this command on the primary server: pcp_recovery_node -h
>> 192.168.80.90 -p 9898 -U postgres -n 1 And received this error:
>> ERROR:  recovery is checking if postmaster is started
>> DETAIL:  postmaster on hostname:"ltpgsql12" database:"template1"
>> user:"postgres" failed to start in 90 second
>> 
>> How can I get this command to run successfully?
> 
> Probably you have a problem with ssh settings. The newer and original document describes far detailed steps to set up ssh settings. Please take a look at "7.3.2. Requirements" section in the newer document.
> 
> In the mean time to confirm that the problem is related to ssh, we need to look into the PostgreSQL log (not Pgpool-II log) on primary PostgreSQL node. Please share it (again, you'd better to post messages to the pgpool-general mailing list).
> 
>> Also, when I ran this command: psql -p 5433 -c "show pool_nodes"
>> It shows the following pgpool2 node status, but when I did a listing 
>> of databases on the primary and standby servers, I don't see the 
>> databases on the primary replicated to the standby.  How can I setup 
>> the Postgresql Streaming Replication and check if it's working?
> 
> Standby status is down because you failed to execute online recovery. You need to fix it.
> 
>> node_id | hostname  | port | status | lb_weight |  role   | select_cnt |
>> load_balance_node | replication_delay | replication_state | 
>> replication_sync_state | last_status_change
>> ---------+-----------+------+--------+-----------+---------+------------+-------------------+-------------------+-------------------+------------------------+---------------------
>>  0       | ltpgsql11 | 6432 | up     | 0.500000  | primary | 0          |
>> true              | 0                 |                   |                       
>> | 2020-10-21 11:56:48
>>  1       | ltpgsql12 | 6432 | down   | 0.500000  | standby | 0          |
>> false             | 0                 |                   |                       
>> | 2020-10-21 11:56:48
>> (2 rows)
>> 
>> 
>> Thanks,
>> Alan
>> 
>> 
>> 
>> --
>> Sent from: 
>> https://www.postgresql-archive.org/PostgreSQL-general-f1843780.html
>> 
>>

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