深入了解 Oracle 日志查看方式（oracle日志查看）

In order to better understand and make use of Oracle systems and databases, we must have a good understanding of Oracle logs, their purpose and how to view them.

Oracle logs are designed to provide the database administrator with detailed information about the Oracle database and services. The logs are used to record the activities that the database and services have performed, the errors that have occurred, and any other details that may be of interest to the administrator.

There are four main types of Oracle log: alert logs, value-added logs, event logs and trace logs. Alert logs provide information about errors that may have been encountered while performing database operations. Value-added logs provide additional information about the activities that were performed, such as the details of a particular query executed. Event logs record the occurrence of ‘events’ within the database, such as ‘startup’ or ‘shutdown’. Finally, trace logs provide a detailed trail of the execution history of an SQL statement.

When a database administrator needs to view one of these logs, there are a number of approaches available. To view the alert log, the administrator may use the Oracle Database Log Viewer, or the sqlplus command line interface. The value-added log can be viewed through the Enterprise Manager or the sqlplus command line interface. For the event log and trace logs, the administrator may use the Enterprise Manager or the Trace Analyzer command line tool.

It is also possible to view the logs programmatically. For example, an Oracle Database Connect module may be used to query the contents of the log tables. Here is an example of a query that can be used to view the contents of an alert log:

SELECT * FROM V$ALERT_LOG WHERE Message LIKE ‘%error%’;

This query would return all rows in the V$ALERT_LOG table where the message contains the word “error”.

Lastly, it is also possible to view the Oracle logs outside of the database. For example, the logmining package allows the administrator to specify certain criteria and then generate reports from the contents of the log files.

In summary, Oracle logs provide a wealth of valuable information and understanding that can be used to troubleshoot and manage the database. Oracle logs can be viewed using Enterprise manager, the Log Viewer, the Trace Analyzer, or programmatically via the database. This allows administrators to quickly identify errors, review performance information, or even trace the execution of an SQL statement.