PostgreSQL Replication Status Test

The process of copying data from a PostgreSQL database server to another server is called PostgreSQL Replication. The source database server is usually called the Master server, whereas the database server receiving the copied data is called the Replica server.

In a high availability environment, the replica servers should always be in sync with the master database instance. For this, the replication should always be enabled on the master and the replica servers should be connected to the master at all times. If the replication fails even for a brief period or if the replica servers are not connected to the master, the replica servers will not be upto date. To avoid this, it is essential to monitor the replication status of the master PostgreSQL database server. The PostgreSQL Replication Status test helps administrators in this regard!

This test reports whether/not the replication process is enabled on the target database server and also helps administrators figure out if the target database server is the master or not. Additionally, this test reports the count of replica servers connected to the target database server.

Target of the test : PostgreSQL server

Agent deploying the test: An internal/remote agent

Outputs of the test : One set of results for the target PostgreSQL server

Configurable parameters for the test
Parameter	Description
Test period	How often should the test be executed
Host	The IP address of the host for which this test is to be configured.
Port	The port on which the server is listening. The default port is 5432.
Username	In order to monitor a PostgreSQL server, you need to manually create a special database user account in every PostgreSQL database instance that requires monitoring. To know how to create such a user based on where the target PostgreSQL server is installed (whether on-premises or hosted on Cloud), refer to How does eG Enterprise Monitor PostgreSQL Server?.
Password	The password associated with the above Username (can be ‘NULL’). Here, ‘NULL’ means that the user does not have any password.
Confirm Password	Confirm the Password (if any) by retyping it here.
DB Name	The name of the database to connect to. The default is “postgres”.
SSL	If the PostgreSQL server being monitored is an SSL-enabled server, then set the SSL flag to Yes. If not, then set the SSL flag to No.
Verify CA	If the eG agent is required to establish an encrypted connection with the target PostGreSQL Database server by authenticating the server's identity through verifying the server CA certificate, set Verify CA flag to Yes. By default, this flag is set to No.
CA Cert File	This parameter is applicable only if the target PostGreSQL Database is SSL-enabled.The certificate file is a public-key certificate following the x.509 standard. It contains information about the identity of the server, such as its name, geolocation, and public key. Each nodes of the target cluster can have individual certificate files or a single certificate can be used to access all the nodes in the cluster. Essentially, it’s a certificate that the server serves to the connecting users to prove that they are what they claim to be. Therefore, specify the full path to the server root certificate or certificate file that is signed by the CA in .crt file format for all/each node in the CA Cert File text box. For example, the location of this file may be: C:\app\eGurkha\JRE\lib\security\PostGreQL-test-ca.crt. By default, this parameter is set to none. This parameter specification differs according to the type of cluster and configuration: If the certificate file is available for each node of the PostGreSQL Cluster then, provide a comma-seperated list of full path to the certificates in CA Cert File text box: For example:C:\app\eGurkha\JRE\lib\security\postgresql-test-ca.crt,C:\app\eGurkha\JRE\lib\security\postgresql-test-ca2.crt,C:\app\eGurkha\JRE\lib\security\postgresql-test-ca3.crt Specify the full path to the certificate file of the target PostGreSQL Database if a single certificate is used to access all nodes. For example: C:\app\eGurkha\JRE\lib\security\postgresql-test-ca.crt
Client Cert File	This parameter is applicable only if the target PostGreSQL Database is SSL-enabled. In order to collect metrics from the target MongoDB cluster, the eG agent requires client certificate in .p12 format. Hence, specify the full path to the Client certificate file in .p12 format in the Client Cert File text box. For example, the location of this file may be: C:\app\eGurkha\JRE\lib\security\test-client.p12.
Client Key File	A client key file refers to a file containing the private key that corresponds to the public key used by a client. Provide full path of the file containing client key.
Detailed Diagnosis	To make diagnosis more efficient and accurate, the eG Enterprise embeds an optional detailed diagnostic capability. With this capability, the eG agents can be configured to run detailed, more elaborate tests as and when specific problems are detected. To enable the detailed diagnosis capability of this test for a particular server, choose the On option. To disable the capability, click on the Off option. The option to selectively enable/disable the detailed diagnosis capability will be available only if the following conditions are fulfilled: The eG manager license should allow the detailed diagnosis capability Both the normal and abnormal frequencies configured for the detailed diagnosis measures should not be 0.

Measurements made by the test

Measurement

Description

Measurement Unit

Interpretation

Is replication enabled?

Indicates whether/not replication is enabled on the target database server.

The values reported by this measure and its numeric equivalents are mentioned in the table below:

Measure Value	Numeric Value
Yes	1
No	0

Note:

By default, this measure reports the Measure Values listed in the table above to indicate whether/not replication is enabled on the server. The graph of this measure however, is represented using the numeric equivalents only i.e., 0 or 1.

Is master?

Indicates whether/not the database server is the master.

The values reported by this measure and its numeric equivalents are mentioned in the table below:

Measure Value	Numeric Value
Yes	1
No	0

Note:

By default, this measure reports the Measure Values listed in the table above to indicate whether/not the server is the master. The graph of this measure however, is represented using the numeric equivalents only i.e., 0 or 1.

Slave nodes

Indicates the number of replica servers attached to the database server.

Number

This measure will be reported only if the Is master? measure reports a value of Yes.

If the value of this measure decreases gradually, backup data could not be replicated by the master database server and hence data could not be retrieved if the master database server crashes.