Lesson 1

When problems occur, Oracle provides two options for getting detailed information. As you learned in the last module, one of these options is the alert log. The other source of information is a trace file. Trace files are generated automatically when a session terminates abnormally. You can also create trace files on demand to diagnose problems. In this module, you will learn how to find and use trace files to detect and diagnose database problems. Specifically, you will be able to:

1. Describe the functions of two types of trace files
2. Find the location of trace files on any Oracle database
3. Interpret information contained in trace files
4. Create Oracle trace files to diagnose problems
5. Set events to produce trace files

In Oracle 19c, there are two primary types of trace files, each serving different functions:

1. Background Trace Files | Function:
   • Background trace files are generated by the background processes of the Oracle database. These processes include critical components like the
     1. Database Writer (DBWR),
     2. Log Writer (LGWR),
     3. System Monitor (SMON),
     4. Process Monitor (PMON)
   • The purpose of these trace files is to log information related to the operations and activities of these background processes. This can include routine tasks like checkpoint operations, instance recovery, and log file switching, as well as unexpected events such as errors or failures in the background processes.
   • These files are crucial for diagnosing issues related to the core functioning of the database instance, such as performance problems, instance crashes, or other system-level issues.
2. User Trace Files | Function:
   • User trace files are generated when specific user sessions encounter errors, experience performance issues, or when tracing is explicitly enabled for a session (e.g., using SQL Trace or DBMS_MONITOR).
   • These trace files contain detailed information about SQL statements executed by the user, including parsing, execution plans, bind variables, and execution statistics. They are instrumental in diagnosing and tuning SQL performance, identifying bottlenecks, and resolving issues related to specific user operations.
   • User trace files are typically used by database administrators and developers to fine-tune queries, analyze performance problems, and troubleshoot issues related to user sessions or applications interacting with the Oracle database.

Summary:

• Background Trace Files focus on logging the operations of the database's background processes, providing insights into the overall health and functionality of the database instance.
• User Trace Files capture detailed information about user sessions, helping in diagnosing performance issues and troubleshooting specific user-related problems.

Both types of trace files are critical tools for maintaining the stability, performance, and reliability of an Oracle database, especially in a production environment.

In Oracle, trace files are used to record detailed information about the performance and behavior of an Oracle database. Trace files can be generated for a variety of purposes, such as debugging, performance analysis, and problem diagnosis. In general, the format and content of trace files in Oracle 18c are similar to those in Oracle 12c. However, there are some differences between the two versions, including:

1. Automatic Diagnostic Repository (ADR): In Oracle 12c, trace files were stored in a user-specified directory. In Oracle 18c, trace files are stored in the ADR, a centralized repository for diagnostic data that is shared by all Oracle components. The ADR provides a standardized location and format for trace files, making it easier to manage and analyze diagnostic data.
2. Enhanced tracing capabilities: Oracle 18c introduced several enhancements to the tracing capabilities of the database, including the ability to trace specific SQL statements, improved tracing of database events, and support for tracing of Unified Audit Trail (UAT) events.
3. Optimizations: Oracle 18c includes various optimizations that improve the performance of tracing, including faster trace file creation and improved buffering of trace data.

Overall, while there are some differences between trace files in Oracle 18c and 12c, the basic purpose and functionality of trace files remain the same. Trace files continue to be an important tool for database administrators and performance analysts to diagnose and troubleshoot issues with Oracle databases.
In the next lesson, you will get an overview of the trace file.