Alert Log Contents

The alert log is a text file that contains text messages generated by the Oracle software as the database is running. These messages are written to alert you to problems and to record significant events in the life of the database. The most common log entry types that you will see are described in this Slide Show:

Many of the messages recorded in the alert log are routine and do not require any special action. Some routine messages, such as those that record physical changes, are useful in recovery situations. Error messages should always be looked at, especially the 600 series of errors.

The truth of the matter is, I do not always chase down each and every error that I see in the alert log. Perhaps I should, and perhaps I shouldn't admit that I don't. Usually what I do is watch to see if an error repeats. If it's a one-time thing, I'll ignore it, especially if I don't have a lot of time to spare. If I get complaints from users or from developers, though, I sometimes find the error messages in the alert log to be an invaluable resource. A developer may remember getting a strange error at a certain time of day, but may not remember what that error was. By looking at the messages in the alert log from around the same time of day, I have a chance of discovering what error occurred and resolving it.