Tales From A Lazy Fat DBA

Hi Everyone,

Today’s post will be all about monitoring your PostgreSQL database clusters using EDB PostgreSQL Enterprise Manager (PEM). Postgres Enterprise Manager is a comprehensive, customizable solution providing an interface to control and optimize your PostgreSQL deployment.

I will be doing the installation, configuration, adding servers to the console and will perform a live monitoring of the database while I will be generating some synthetic load on the database host. I am doing this on a standalone RHEL 7 64 Bit server which I will be using it both as a PEM server and local instance. Alright, so without further ado, lets start. So, first you need to download EDB’s official repository and install following package.

Below is a complete list of packages available with name ‘edb-pem’, you need to install version: edb-pem-8.0.1-1.rhel7.x86_64

[root@canttowin repo]# yum search edb-pem
Loaded plugins: langpacks, ulninfo

=================================================================== N/S matched: edb-pem ====================================================================
edb-pem-debuginfo.x86_64 : Debug information for package edb-pem
edb-pem.x86_64 : PostgreSQL Enterprise Manager
edb-pem-agent.x86_64 : Postgres Enterprise Manager Agent
edb-pem-docs.x86_64 : Documentation for Postgres Enterprise Manager
edb-pem-server.x86_64 : PEM Server Components

Once installation is completed, go to the default installation directory, it’s /usr/edb in my case, and go to pem/bin folder.

[root@canttowin ~]# cd /usr/edb/
[root@canttowin edb]# ls
as12 bart efm-4.1 jdbc migrationtoolkit pem pgbouncer1.15 pgpool4.2
[root@canttowin ~]# cd /usr/edb/pem/bin/
[root@canttowin bin]# ls
configure-pem-server.sh configure-selinux.sh

We see two configuration shell scripts are present, we will be using the configuration script – configure-pem-server.sh
Here I will be choosing option 1 which means I will be installing web services and databases all on one host, next you need to input installation path (/usr/edb/as12 in my case), followed by super user name, port numbers and IP Address of the server.

Before I call the config script, let me quickly reset the default superuser’s password.

postgres=# alter user postgres with password 'dixit';
ALTER ROLE

Now, let’s call the configuration scipt and pass all discussed values.

[root@canttowin bin]# ./configure-pem-server.sh

 -----------------------------------------------------
 EDB Postgres Enterprise Manager
 -----------------------------------------------------
Install type: 1:Web Services and Database, 2:Web Services 3: Database [ ] :1
Enter local database server installation path (i.e. /usr/edb/as12 , or /usr/pgsql-12, etc.) [ ] :/usr/edb/as12
Enter database super user name [ ] :enterprisedb
Enter database server port number [ ] :5444
Enter database super user password [ ] :
Please enter CIDR formatted network address range that agents will connect to the server from, to be added to the server's pg_hba.conf file. For example, 192.168.1.0/24 [ 0.0.0.0/0 ] :10.0.0.153/32
Enter database systemd unit file or init script name (i.e. edb-as-12 or postgresql-12, etc.) [ ] :edb-as-12
Please specify agent certificate path (Script will attempt to create this directory, if it does not exists) [ ~/.pem/ ] :
CREATE EXTENSION
[Info] Configuring database server.
CREATE DATABASE
CREATE ROLE
CREATE ...
..
..
..
CREATE EXTENSION
-->  [Info] -->  [Info] Configuring database server.
-->  [Info] -->  [Info] creating role pem
-->  [Info] -->  [Info] Generating certificates
-->  [Info] -->  [Info] Executing systemctl stop edb-as-12
-->  [Info] -->  [Info] Skipping - configurations for /var/lib/edb/as12/data/pg_hba.conf and /var/lib/edb/as12/data/postgresql.conf file
-->  [Info] -->  [Info] Executing systemctl start edb-as-12
-->  [Info] -->  [Info] Enable pemagent service.
-->  [Info] -->  [Info] Executing systemctl enable pemagent
-->  [Info] -->  [Info] Stop pemagent service
-->  [Info] -->  [Info] Executing systemctl stop pemagent
-->  [Info] -->  [Info] Start pemagent service.
-->  [Info] -->  [Info] Executing systemctl start pemagent
-->  [Info] -->  [Info] Configuring httpd server
-->  [Info] -->  [Info] Executing systemctl stop httpd
-->  [Info] -->  [Info] Taking backup of /usr/edb/pem/web/pem.wsgi
-->  [Info] -->  [Info] Creating /usr/edb/pem/web/pem.wsgi
-->  [Info] -->  [Info] Taking backup of /usr/edb/pem/web/config_local.py.
-->  [Info] -->  [Info] Generating PEM Cookie Name.
-->  [Info] -->  [Info] Creating /usr/edb/pem/web/config_local.py
-->  [Info] -->  [Info] Taking backup of /etc/httpd/conf.d/edb-pem.conf
-->  [Info] -->  [Info] Creating /etc/httpd/conf.d/edb-pem.conf
-->  [Info] -->  [Info] Configuring httpd server sslconf
-->  [Info] -->  [Info] Taking backup of /etc/httpd/conf.d/edb-ssl-pem.conf
-->  [Info] -->  [Info] Taking backup of /etc/httpd/conf.d/edb-ssl-pem.conf
-->  [Info] -->  [Info] Executing /usr/edb/pem/web/setup.py
Postgres Enterprise Manager - Application Initialisation
========================================================
-->  [Info] -->  [Info] Check and Configure SELinux security policy for PEM
 getenforce found, now executing 'getenforce' command
 Configure the httpd to work with the SELinux
 Allow the httpd to connect the database (httpd_can_network_connect_db = on)
 Allow the httpd to connect the network (httpd_can_network_connect = on)
 Allow the httpd to work with cgi (httpd_enable_cgi = on)
 Allow to read & write permission on the 'pem' user home directory
 SELinux policy is configured for PEM
-->  [Info] -->  [Info] Executing systemctl start httpd
-->  [Info] -->  [Info] Configured the webservice for EDB Postgres Enterprise Manager (PEM) Server on port '8443'.
-->  [Info] -->  [Info] PEM server can be accessed at https://127.0.0.1:8443/pem at your browser

It’s completed, and at the very end it has provided URL to access the PEM GUI.

Now next step is to install PEM Agents to the server, you need to install it on all servers which you want to monitor, I am leaving the PEMAgents configuration that you do in agent.cfg file.

[root@canttowin bin]# yum install edb-pem-agent

Let’s check the PEM GUI now.

Here on the left panel you will notice there’s already one database present under ‘PEM Server Directory’ folder, this is the same database which we have configured/used PEM server, hence it will be automatically added to the server list. We will manually add one more database cluster to explain how to do it explicitly.

Let’s check the dashboard for the same (PEM Server) database for session, TPS, IO related details.

Now, let’s add another database to the monitoring console. I will be adding a community PostgreSQL 12 database to it. Go to ‘PEM Server Directory’ folder right click on it, choose option create-> server.

Next, fill connection wizard with all details i.e, username, password, IP, port and security related details for the new database and click save at the end.

And you are done!

Now, let’s see the default landing page of PEM GUI and here you see details of all added hosts and agents with their status.

Next I will create some new databases to see how that data reflects in PEM GUI.
postgres=#
postgres=# create database dixit;
CREATE DATABASE
postgres=# create database kartikey;
CREATE DATABASE

postgres=# \l
List of databases
Name | Owner | Encoding | Collate | Ctype | Access privileges | Size
-----------+----------+----------+-------------+-------------+-----------------------+--------
dixit | postgres | UTF8 | en_US.UTF-8 | en_US.UTF-8 | | 8049 kB
kartikey | postgres | UTF8 | en_US.UTF-8 | en_US.UTF-8 | | 8049 kB
postgres | postgres | UTF8 | en_US.UTF-8 | en_US.UTF-8 | | 8193 kB

(3 rows)

All good! now let’s do some performance test to see how useful PEM can be in case of performance issues. In order to mimic or simulate the situation, I will generating some synthetic load using PostgreSQL’s default utility Pgbench.

Reference:
-c number of clients
-j 2 number of threads
-t amount of transactions

These values are 10000 transactions per client. So : 10 x 10000 = 100,000 transactions

[postgres@canttowin bin]$ ./pgbench -U postgres -p 5432 -c 10 -j 2 -t 10000 postgres
starting vacuum…end.

Let’s see how the changes are captured and presented in PEM.

Okay, we can see the peaks are recorded and presented.

The load is still running and we can clearly see that from the below graph.

[postgres@canttowin bin]$ ./pgbench -U postgres -p 5432 -c 10 -j 2 -t 10000 postgres
starting vacuum…end.transaction type:
scaling factor: 1
query mode: simple
number of clients: 10
number of threads: 2
number of transactions per client: 10000
number of transactions actually processed: 100000/100000
latency average = 18.217 ms
tps = 548.940142 (including connections establishing)
tps = 548.970173 (excluding connections establishing)

Alright, so the load run has ended, let see how the graph now looks like.

So to conclude, PEM is a great tool which can fulfil all your monitoring needs, it has got some cool features too i.e. performance dashboards, tuning wizards, advisories and other graphs.

Hope It Helped
Prashant Dixit