EMLight is a web based application for exploring Oracle Database instances and monitoring their activity. A light version of Oracle Enterprise Manager DB Console without associated overhead, so to speak.
Yes, that’s it. You only need the database you want to monitor and a web browser capable of displaying SVG graphics we occasionally use for charts and images. No additional software on the server and no additional software on your desktop, laptop or mobile device.
EMLight conveniently displays essential information about your database and instance in your web browser of choice, including, but not limited to, the following:
And most bits of the information displayed are clickable for further details. For example, active sessions display allows you to drill down to particular statement being executed in a session and from that to its plan, execution statistics, etc.
As an Oracle DBA, you are typically responsible for keeping your databases secure and preventing unauthorized access to the mission-critical data stored in them. Security-conscious DBAs consider every additional access path into the database as a potential security hole, so they typically avoid installing into, or close to, their databases anything that might pose additional security risks. How does EMLight fit the picture?
The first thing to know about EMLight is that it’s read-only, and is confined to a certain limited set of database views it can read from. It was purposedly designed that way – as a light and simple monitoring tool, not a DBA’s swiss army knife. You can’t change anything in the database using it, be it an initialization parameter or a job definition, and you can’t access any object out of the application scope through it. EMLight can show you where a performance or operational issue can be, but to fix that issue you should use other tools (like SQL*Plus) that have full access to the database you control. And it’s light on the system being monitored: when activated, it strives to consume as little system resources as possible so as to not get in the way of primary system workload.
Since some data EMLight displays can still reveal sensitive information about your database (like SQL statements, database file paths, other bits of information that may aid an intruder in penetrating your defenses and breaking into the database,) it is highly recommended that you secure EMLight access point after installation so that only authorized personnel could access it.
Check out or screenshot gallery. If you are familiar with Oracle Enterprise Manager Grid Control or DB Console, you will probably spot the similarities. They are intentional.
Download EMLight here and refer to the installation instructions for step-by-step guide to get your first EMLight instance running. It also describes how to restrict access to the application to authorized people only.
EMLight uses system performance diagnostic and monitoring views provided by Oracle Diagnostic Pack. Oracle Diagnostic Pack is additionally licensable Oracle Database option and in order to use it you must purchase license for the Diagnostic Pack from Oracle.