Oracle Oracle Database 19c: Performance Management and Tuning 1z0-084 Exam Dumps: Updated Questions & Answers (October 2025)

To configure and enable Database Smart Flash Cache, you must set the DB_FLASH_CACHE_SIZE parameter to reflect the combined size of the flash devices you intend to use for the cache. In this scenario, two flash devices are configured: /dev/sdj with 128G and /dev/sdk with 64G.

Determine the combined size of the flash devices intended for the Database Smart Flash Cache. In this case, it's 128G + 64G = 192G.

However, Oracle documentation suggests setting DB_FLASH_CACHE_SIZE to the exact sizes of the individual devices, separated by a comma when multiple devices are used.

Modify the parameter in the database initialization file (init.ora or spfile.ora) or using an ALTER SYSTEM command. Here's the command for altering the system setting:

ALTER SYSTEM SET DB_FLASH_CACHE_SIZE='128G,64G' SCOPE=SPFILE;

Since this is a static parameter, a database restart is required for the changes to take effect.

Upon database startup, it will allocate the Database Smart Flash Cache using the provided sizes for the specified devices.

It is important to note that MEMORY_TARGET and MEMORY_MAX_TARGET parameters should be configured independently of DB_FLASH_CACHE_SIZE. They control the Oracle memory management for the SGA and PGA, and do not directly correlate with the flash cache configuration.

References

Oracle Database 19c Documentation on Database Smart Flash Cache

Oracle Support Articles and Community Discussions on DB_FLASH_CACHE_SIZE Configuration

In the provided code block, the DBMS_SERVER_ALERT.SET_THRESHOLD procedure is used to set alert thresholds for the CPU time per call in Oracle Database. This procedure is a part of Oracle's Database Server Alert system, which monitors various metrics and generates alerts when certain thresholds are exceeded.

The parameters passed to the SET_THRESHOLD procedure are as follows:

The first parameter DBMS_SERVER_ALERT.CPU_TIME_PER_CALL specifies the metric for which the threshold is being set, in this case, the CPU time consumed per database call.

The second and third parameters DBMS_SERVER_ALERT.OPERATOR_GE and '8000' specify the warning threshold level and its value, respectively. However, these are not relevant to the answer as they are overridden by the critical threshold settings.

The fourth and fifth parameters DBMS_SERVER_ALERT.OPERATOR_GE and '10000' set the critical threshold level and its value. This means that a critical alert will be generated when the CPU time per call exceeds 10000 microseconds.

The remaining parameters specify the warning and critical alert intervals, the instance name, the object type, and the service name. These are not directly relevant to the behavior described in the options.

Thus, the correct answer is B, as the critical threshold for CPU time per call is set to 10000 microseconds, and the system is configured to issue a critical alert when this threshold is exceeded.

References:

Oracle Database 19c documentation on the DBMS_SERVER_ALERT.SET_THRESHOLD procedure, which details the parameters and usage of this procedure for setting alert thresholds within Oracle Database monitoring system.

Oracle Database Performance Tuning Guide, which provides best practices and methodologies for monitoring and tuning Oracle Database performance, including the use of server alerts and thresholds.

When you enable statistics gathering for a specific service and module using DBMS_MONITOR.SERV_MOD_ACT_STAT_ENABLE, the output is aggregated and can be viewed using the V$SERV_MOD_ACT_STATS dynamic performance view. This view contains the cumulative statistics of database activity broken down by service and module, which is exactly what you collect when executing the provided command.

B (Incorrect): While many types of trace files are located in the Diagnostic Destination directory ($ORACLE_BASE/diag), the aggregated statistics for services and modules are not written to trace files but are instead viewable through dynamic performance views.

C (Incorrect): The V$SERVICE_STATS view provides service-level statistics but does not provide the combined service/module-level breakdown.

D (Incorrect): The output of the PL/SQL block is not written to a file in the current working directory; it is stored in the data dictionary and accessible via dynamic performance views.

References:

Oracle Database PL/SQL Packages and Types Reference: DBMS_MONITOR

Oracle Database Reference: V$SERV_MOD_ACT_STATS

The query output from V$PGA_TARGET_ADVICE provides tuning information for the PGA (Program Global Area). Let’s break it down step by step:

Key Columns in the Output:

TARGET_MB:

Represents the hypothetical PGA_AGGREGATE_TARGET values (in megabytes) evaluated by Oracle.

CACHE_HIT_PERC:

The percentage of work areas that could execute in-memory (optimal execution) without requiring temporary disk writes.

Higher percentages indicate fewer work areas requiring disk I/O.

ESTD_OVERALLOC_COUNT:

The estimated number of work areas that need to go to disk (multipass operations or overallocations).

Observations from the Data:

At TARGET_MB = 700 MB:

The CACHE_HIT_PERC is 68%.

The ESTD_OVERALLOC_COUNT is 30. This indicates that some multipass work areas still exist.

At TARGET_MB = 800 MB:

The CACHE_HIT_PERC rises to 74%.

The ESTD_OVERALLOC_COUNT drops to 0. This indicates that no work areas require multipass execution.

At TARGET_MB = 900 MB and above:

The CACHE_HIT_PERC increases slightly to 82%-84%.

The ESTD_OVERALLOC_COUNT remains 0, meaning that all work areas are now either optimal or one-pass.

Why D is Correct:

At 800 MB or more, the ESTD_OVERALLOC_COUNT is 0, indicating that all one-pass execution work areas are eliminated.

A one-pass execution requires temporary disk I/O for intermediate results, but with sufficient PGA, these are no longer necessary.

Why Other Options Are Incorrect:

Option A:

It mentions all multipass executions work areas would be eliminated at 700 MB. This is incorrect because, at 700 MB, the ESTD_OVERALLOC_COUNT is still 30, indicating some multipass work areas still exist.

Option B:

Suggests setting the PGA_AGGREGATE_TARGET to at least 800 MB, which is partially correct but does not address the elimination of one-pass execution.

Option C:

Suggests setting the PGA_AGGREGATE_TARGET to at least 700 MB, which is not sufficient to eliminate all one-pass executions, as shown by the ESTD_OVERALLOC_COUNT of 30.

SQL Performance Analyzer (SPA) can be used to assess the impact of different types of changes on SQL performance. These changes can include database initialization parameters, which can significantly affect how SQL statements are executed and therefore their performance. SPA allows you to capture a workload before and after the change and compare the performance of each SQL statement.

Database consolidation, including moving to pluggable databases (PDBs), can also affect SQL performance. SPA can analyze the SQL workload to see how consolidation impacts performance, by comparing metrics such as elapsed time and CPU time before and after the consolidation.

References:

Oracle Database SQL Tuning Guide, 19c

Oracle Database Performance Tuning Guide, 19c

Statspack is a performance diagnostic tool provided by Oracle prior to the introduction of the Automatic Workload Repository (AWR). At snap level 6, Statspack captures the following types of statistics:

A (Correct): Parent and child latches are captured. Latch statistics provide information about contention for latches, which are low-level serialization mechanisms used by Oracle.

E (Correct): Enqueue statistics, which provide information on the waits for locks that manage the concurrency between users.

F (Correct): Segment-level statistics, which provide detailed information on database segments such as tables, indexes, etc., to identify I/O and contention issues.

C (Incorrect): While optimizer execution plans are an essential aspect of performance tuning, detailed execution plan capture is not part of the Statspack report at level 6.

D (Incorrect): Plan usage data refers to how frequently a plan is being used, which is more associated with AWR and not typically captured in Statspack reports.

References:

Oracle Database Performance Tuning Guide: Using Statspack

A. When Cursor_sharing is set to FORCE, Oracle tries to avoid hard parses by replacing literals in SQL statements with bind variables, even if the original statement didn't include bind variables. This can lead to the use of a single execution plan for multiple executions of a statement with different literal values, which might not be optimal for all executions.

D. Setting cursor_sharing to EXACT ensures that SQL statements must match exactly for them to share a cursor. This setting prevents the use of Adaptive Cursor Sharing (ACS) since ACS relies on the ability to share cursors among similar statements that differ only in their literal values. With EXACT, there's no cursor sharing for statements with different literals, hence no opportunity for ACS to operate.

References:

Oracle Database SQL Tuning Guide, 19c

Oracle Database Reference, 19c

When an ORA-00060 deadlock error occurs, detailed information about the error and the deadlock graph are dumped into the alert log. This log contains a trace file name that you can use to find additional detailed information about the sessions involved in the deadlock and the SQL statements they were executing.References:

Oracle Database Administrator’s Guide, 19c

Oracle Database Error Messages, 19c

The production phase of the application lifecycle is often managed reactively. While proactive measures and performance tuning are essential, unforeseen issues can arise in production that require immediate attention and resolution. Reactive management involves monitoring performance and responding to issues as they occur, ensuring the application maintains acceptable performance levels for end-users.

References

Oracle Database 19c Performance Tuning Guide - Reactive Tuning

A. Statspack is a performance diagnostic tool that can help identify high CPU usage issues. High CPU time may indicate that SQL statements need to be tuned for better performance.

D. High wait times can often be reduced by instance tuning, such as adjusting database parameters or improving I/O performance.

F. DB Time is a cumulative time metric that includes the time spent by both user sessions and background processes executing database calls.References:

Oracle Database Performance Tuning Guide, 19c

Oracle Database Concepts, 19c