Tuesday, June 4, 2013

Setting up everything at one time

While developping pgpool-II 3.3, I created a small script to make developer's life a little bit easier. However, the tool might be useful for PostgreSQL/pgpool-II beginners. So I decided to introduce it in my blog.

Disclaimer: the environment created by the tool below should never be used for production.

The script is called "pgpool_setup".  It creates followings by just one command under current directory. The directory must be empty. PostgreSQL and pgpool binaries must be installed and in your command search path beforehand.
  • PostgreSQL clusters. You can choose "streaming replication mode" or "native replication mode". The former you already know, I assume. The latter is just a set of identical PostgreSQL clusters except the port numbers are different.
  • If you choose streaming replication mode, one primary server and standby servers are ready after the command runs (even with WAL archival is enabled).
  • By default those PostgreSQL cluster port number start from 11000 and continues 11001, 11002 and so on.
  • The port numbers of pgpool and pcp follow.
  • One pgpool server, with failover/online recovery/followmaster command are all set.
  • A test database "test" is created.
  • pcp commands(which are for pgpool administrator) account and password are ready for you.
By running pgpool_setup, you are ready to start pgpool and PostgreSQL with complete settings (at least for testing pupose) on your computer. I use this tool to create multiple groups  of pgpool+PostgreSQL set on my laptop.

So here's a sample session.

$ pgpool_setup
Satrting set up in streaming replication mode
creating startall and shutdownall
creating failover script
creating database cluster /home/t-ishii/work/git.postgresql.org/tmp2/data0...done.
update postgreql.conf
creating pgpool_remote_start
creating basebackup.sh
creating recovery.conf
creating database cluster /home/t-ishii/work/git.postgresql.org/tmp2/data1...done.
update postgreql.conf
creating pgpool_remote_start
creating basebackup.sh
creating recovery.conf
temporarily start data0 cluster to create extensions
temporarily start pgpool-II to create standby nodes
waiting for failover happens...done.
 node_id | hostname | port  | status | lb_weight |  role   
---------+----------+-------+--------+-----------+---------
 0       | /tmp     | 11000 | 2      | 0.500000  | primary
 1       | /tmp     | 11001 | 3      | 0.500000  | standby
(2 rows)

recovery node 1...done.
creating follow master script
Pager usage is off.
 node_id | hostname | port  | status | lb_weight |  role   
---------+----------+-------+--------+-----------+---------
 0       | /tmp     | 11000 | 2      | 0.500000  | primary
 1       | /tmp     | 11001 | 2      | 0.500000  | standby
(2 rows)

shutdown all

pgpool-II setting for streaming replication mode is done.
To start the whole system, use /home/t-ishii/work/git.postgresql.org/tmp2/startall.
To shutdown the whole system, use /home/t-ishii/work/git.postgresql.org/tmp2/shutdownall.
pcp command user name is "t-ishii", password is "t-ishii".
Each PostgreSQL, pgpool-II and pcp port is as follows:
#1 port is 11000
#2 port is 11001
pgpool port is 11002
pcp port is 11003
The info above is in README.port.
$ ls
README.port  bashrc.ports*  data1/  log/              run/          startall*
archivedir/  data0/         etc/    pgpool_setup.log  shutdownall

# So here you can see PostgreSQL cluster 0 as "data0" and cluster 1 as
# "data1".  You can start everything (pgpool and PostgreSQL) by using
# "startall", which is creaeted by the comand.

$ sh startall
waiting for server to start.... done
server started
waiting for server to start.... done
server started

# Make sure primary and standby are running.  "show pool_nodes" shows
# the info. Port 11002 is the port for pgpool.  As you can see
# primary's port is 11000 and standby's port is 11001.
# Status "2" means up and running.

$ psql -p 11002 -c 'show pool_nodes' test
 node_id | hostname | port  | status | lb_weight |  role   
---------+----------+-------+--------+-----------+---------
 0       | /tmp     | 11000 | 2      | 0.500000  | primary
 1       | /tmp     | 11001 | 2      | 0.500000  | standby
(2 rows)

# Now let's make sure that streaming replication is activated.

$ psql -p 11002 test
Pager usage is off.
psql (9.3beta1)
Type "help" for help.

test=# create table t1(i int);
CREATE TABLE
test=# insert into t1 values(1);
INSERT 0 1
test=# select * from t1;
 i 
---
 1
(1 row)

test=# \q

# Connect to standby.
$ psql -p 11001 test
Pager usage is off.
psql (9.3beta1)
Type "help" for help.

test=# select * from t1;
 i 
---
 1
(1 row)

test=# \q

# Ok, "t1" is propagated.

# Next test failover. So shutdown standby.

$ pg_ctl -D data1 -m f stop
waiting for server to shut down.... done
server stopped
$ psql -p 11002 -c 'show pool_nodes' test
 node_id | hostname | port  | status | lb_weight |  role   
---------+----------+-------+--------+-----------+---------
 0       | /tmp     | 11000 | 2      | 0.500000  | primary
 1       | /tmp     | 11001 | 3      | 0.500000  | standby
(2 rows)

# Note that status "3" means down.

# Let's stary standby and make it online.
$ pg_ctl -D data1 start
server starting
$ pcp_attach_node 1 localhost 11003 t-ishii t-ishii 1
$ psql -p 11002 -c 'show pool_nodes' test
 node_id | hostname | port  | status | lb_weight |  role   
---------+----------+-------+--------+-----------+---------
 0       | /tmp     | 11000 | 2      | 0.500000  | primary
 1       | /tmp     | 11001 | 2      | 0.500000  | standby
(2 rows)

# Next test is promotion. Let's stop primary and see if standby promotes.

$ pg_ctl -D data0 -m f stop
waiting for server to shut down.... done
server stopped

# Wait for while to let our failover script and follow master script do the job.

$ psql -p 11002 -c 'show pool_nodes' test
 node_id | hostname | port  | status | lb_weight |  role   
---------+----------+-------+--------+-----------+---------
 0       | /tmp     | 11000 | 2      | 0.500000  | standby
 1       | /tmp     | 11001 | 2      | 0.500000  | primary
(2 rows)

# Ok, now node 0 is standby, and 1 is primary. 
 
pgpool_setup is available here.
 

5 comments:

  1. Pretty nice post. I have in fact enjoyed reading your website posts. I have been googling blogs and sites in related manner recently and i have to state you have a nice

    Toshiba PVT-375BT

    ReplyDelete
  2. pgpool_setup link is not working. And I have been going through setup for quite sometime and not able to set it up for my postgres cluster.

    Does pgpool create this show pool_nodes table automatically?

    It will be really helpful if you share the above setup scripts.

    ReplyDelete
    Replies
    1. This comment has been removed by the author.

      Delete
    2. Got it. It can be checked using command with pgpool ip and port from anywhere with psql command: psql -h x.x.x.x -p 5432 -x -c "show pool_nodes;"

      Delete
  3. I am not able to see the script.

    Can u please email me at dtrkishore@gmail.com

    ReplyDelete