PostgreSQL Unused Indexes Test

While at one end indexes greatly enhance database performance, at the other they also add significant overhead to table change operations. Useless/unused indices can therefore be unnecessary resource hogs. Such indexes are typically not used by any regular query and may not enforce a constraint. However, these unneeded indexes cost you in several ways: they slow updates, inserts and deletes; they may keep HOT from updating the row in-place, requiring more VACUUMs; they take time to VACUUM; they add to query planning time; they take time to backup and restore. Administrators hence need to identify such indexes and eliminate them. The PostgreSQL Unused Indexes test helps administrators achieve the same. This test reports the number and names of unused/useless indexes, and thus prompts administrators to remove them so as to save the server from unnecessary performance degradations.

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
  1. TEST PERIOD – How often should the test be executed.
  2. Host – The IP address of the server.
  3. Port – The port on which the server is listening. The default port is 5432.
  4. User – 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. When doing so, ensure that this user is vested with the superuser privileges. The sample script we recommend for user creation for eG monitoring is:

    CREATE ROLE eguser LOGIN

    ENCRYPTED PASSWORD {‘eguser password’}

    SUPERUSER NOINHERIT NOCREATEDB NOCREATEROLE;

    The name of this user has to be specified in the USERNAME text box.

  5. Password- The password associated with the above user name (can be ‘NULL’). Here, ‘NULL’ means that the user does not have any password.
  6. Confirm password – Confirm the password (if any) by retyping it here.
  7. dbname - The name of the database to connect to. The default is “postgres”.
  8. include db - Specify a comma-separated list of databases that you wish to monitor.
  9. exclude db - Specify a comma-separated list of databases that need to be excluded from monitoring. By default, this is set to rdsadmin.

  10. Note:

    If you are monitoring a PostgreSQL server on the AWS EC2 cloud, then make sure that you do not remove 'rdsadmin' from the EXCLUDE DB list.

  11. ssl - The name of this user has to be specified in the USERNAME text box.
  12. To make diagnosis more efficient and accurate, the eG Enterprise suite 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

Number of indexes:

Indicates the number of indexes that are currently unused/useless on the server.

Number

A high value of this measure is a cause for concern. Use the detailed diagnosis of this measure to identify the unused indexes and take measures to get rid of them.