How to view logs in oracle

Oracle is a very popular relational database management system that provides many useful functions to monitor the health of the database. One of these is the ability to view database logs so that we can track and diagnose problems in the database. This article will introduce how to view logs in Oracle.

1. Overview

In the Oracle database, there are many types of log records, including audit logs, trace files, log files, etc. The contents of these log records include transactions that occur in the database, execution of SQL statements, error logs, etc.

2. View log files

If you want to view the log files of the Oracle database, you need to use the viewer tool. How to use this tool is as follows:

First, find the path to the log file of the database. On Unix or Linux systems, Oracle's log files are usually located under the $ORACLE_HOME/diag/rdbms///trace path. On Windows systems, it is usually located under the %ORACLE_HOME%\diag\rdbms\\\trace path.

Then, use the viewer program to open the log file. This program is in the $ORACLE_HOME/bin path and its name is "adrci". For example, to open the log file of the test library, you can use the following command:

$ORACLE_HOME/bin/adrci

Query path:

$ cd /u01/app/oracle /diag/rdbms/orcl/ORCL/trace

$ adrci
adrci> set home orcl // Set path
adrci> show alert -tail -f // View alert log file real-time output

Enter the interactive interface after opening the program and enter the following command:

set homepath path

Among them, path is the one mentioned above The path to the database log file.

Next, you can use the following command to view the log file:

1. show alert -tail -f

This command can view the real-time output of the log file, Can be used to monitor errors and warning messages in the system.

2. show alert -p "message_text like '%keyword%'"

This command can find log entries where specific keywords appear and can be used to track specific issues. happened.

3. show alert -term

This command can output the log file to the terminal and can be used to analyze and debug problems.

The above three commands are only part of viewing the log file. If you want to view more detailed information, you can view the Oracle documentation.

3. View trace files

In addition to log files, Oracle database also has a trace file that can be used to diagnose problems. Trace files are some information recorded when Oracle is running, including the execution of SQL statements, system response, fault information, etc. If you have performance issues or other errors with your database, you can use trace files to help you find the problem.

There are two types of tracking files in Oracle database: user tracking files and background tracking files. User tracking files are under user control and can be included in the application. Background trace files are automatically generated by Oracle database and are usually used for debugging and maintenance purposes.

To view the trace file, you can use the following steps:

1. Open the trace file

First, use the query statement to open the trace file:

ALTER SESSION SET tracefile_identifier = "Identifier file name";

The "identifier file name" can be freely selected and can be used to distinguish different trace files.

2. Execute SQL statements

Next, execute the SQL statements that need to be traced.

3. Close the tracking file

After you complete the tracking analysis, you must close the tracking file to avoid occupying system resources.

ALTER SESSION SET tracefile_identifier = "";

The above are the basic steps for viewing Oracle database logs and trace files. When using logs and trace files for debugging and maintenance, you need to pay attention to the following points:

1. Tracing files will generate a large amount of data and occupy a large amount of disk space, so be sure to close the tracing files after use.
2. When viewing logs and trace files, you need to pay attention to filtering out information related to the problem to avoid wasting time and energy.
3. If you have other issues that need to be tracked and debugged, please check Oracle's official documentation, which provides more detailed operating guidelines and suggestions.

In short, viewing Oracle database logs and trace files is an important task for database debugging and maintenance. Mastering this skill can help you better manage the database.

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