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The Oracle 1Z0-084 exam covers a wide range of topics related to performance and tuning management. These topics include database performance tuning, performance monitoring, SQL tuning, indexing strategies, and more. Candidates are expected to have a strong understanding of these topics and be able to apply their knowledge to real-world situations.
Oracle Database 19c Performance and Tuning Management certification exam consists of 80 multiple-choice questions that need to be completed within 120 minutes. 1Z0-084 exam covers various topics such as database performance analysis, SQL tuning, memory management, and resource management. The candidates need to demonstrate their proficiency in these areas to pass the exam.
If you are a database professional looking to validate your skills in performance and tuning management, then the Oracle 1Z0-084 exam is the right choice for you. Oracle Database 19c Performance and Tuning Management certification not only enhances your credibility in the industry but also opens up new career opportunities. With the right preparation and practice, you can pass 1Z0-084 exam and join the elite group of Oracle certified professionals.
NEW QUESTION # 26
Examine this code block, which executes successfully:
DBMS_SERVER_ALERT. SET_THRESHOLD (
DBMS_SERVER_ALERT.CPU_TIME_PER_CALL, DBMS_SERVER_ALERT. OPERATOR_GE, '8000', DBMS_SERVER_ALERT.OPERATOR_GE, '10000', 1, 2, 'inst1', DBMS_SERVER_ALERT.OBJECT_TYPE_SERVICE, 'main.regress.rdbms.dev.us.example.com') ;
What will happen?
- A. A warning alert will be issued when CPU time exceeds 1 minute for each user call.
- B. A warning alert will be issued only when CPU time exceeds 10000 microseconds for each user call.
- C. A critical alert will be issued when CPU time exceeds 2 minutes for each user call.
- D. A critical alert will be issued when CPU time exceeds 10000 microseconds for each user call.
Answer: D
Explanation:
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.
NEW QUESTION # 27
What are the least elevated values of statistics_level and C0NTR0LJ4ANAGEMENT_PACK_ACCESS that allow the usage of Monitoring of Database Operations?
- A. STATISTICS_LEVEL=TYPICAL and CONTROL_MANAGEMENT_PACK_ACCESS-
DIAGOSTIC*TUNING - B. STATISTICS_LEVEL=ALL and
CONTROL_MANAGEMENT_PACK_ACCESS=DIAGOSTIC+TUNING - C. STATISTICS_LEVEL=TYPICAL and CONTROL_MANAGEMENT_PACK_ACCESS=DIAGOSTIC
- D. STATISTICS_LEVEL=BASIC and CONTROL_MANAGEMENT_PACK ACCESS=DIAGOSTIC
Answer: B
Explanation:
Monitoring of Database Operations requires that the STATISTICS_LEVEL parameter be set to ALL and CONTROL_MANAGEMENT_PACK_ACCESS be set to DIAGNOSTIC+TUNING. These settings enable all the advisory features and automatic tuning features within the Oracle Database, including the Automatic Workload Repository (AWR), Automatic Database Diagnostic Monitor (ADDM), and the full functionality of the SQL Tuning Advisor and SQL Access Advisor, which are components of the Diagnostic and Tuning packs.
* STATISTICS_LEVEL=ALL: This setting enables the collection of all system statistics for problem detection and self-tuning purposes.
* CONTROL_MANAGEMENT_PACK_ACCESS=DIAGNOSTIC+TUNING: This grants access to both the Diagnostic Pack and the Tuning Pack, which are essential for detailed performance monitoring and tuning capabilities.
References:
* Oracle Database Reference: STATISTICS_LEVEL
* Oracle Database Licensing Information User Manual: Oracle Database Management Packs
NEW QUESTION # 28
A database instance is suffering poor I/O performance on two frequently accessed large tables.
No Big Table caching occurs in the database.
Examine these parameter settings:
Which are two actions either one of which will allow Big Table caching to occur?
- A. Increasing DB_BIG_TABLE_CACHE_PERCENT_TARGET to at least 25
- B. Increasing DB_BIG_TABLE_CACHE_PERCENT_TARGET to at least 50
- C. Setting PARALLEL_DEGREE_POLICYADAPTIVE
- D. Increasing DB_CACHESIZE to 1 G
- E. Setting PARALLEL_DEGREE_POLICYAUTO
- F. Setting DB_KEEP_CACHE_SIZE to at least 50M
Answer: A,D
Explanation:
Big Table caching is a feature that allows frequently accessed large tables to be cached in memory to improve I/O performance. From the parameter settings provided, Big Table caching is not occurring because DB_BIG_TABLE_CACHE_PERCENT_TARGETis set to 10, which is the minimum threshold for enabling the feature, but the size of the cache is too small for the big tables to be effectively cached.
To enable Big Table caching, one of the following actions could be taken:
* C (Correct):IncreasingDB_BIG_TABLE_CACHE_PERCENT_TARGETto at least 25. This action would allocate a larger percentage of the buffer cache for storing big tables, which could allow for caching large tables and thus improve I/O performance.
* D (Correct):IncreasingDB_CACHE_SIZEto 1G. Since the size of the buffer cache is a determining factor for how much data can be cached, increasing this parameter would provide more memory space for big tables to be cached.
Options A, B, E, and F will not enable Big Table caching because:
* A:IncreasingDB_BIG_TABLE_CACHE_PERCENT_TARGETto 50 without adjusting the overall size of the cache might still not be sufficient if theDB_CACHE_SIZEis not large enough to hold the big tables.
* B:SettingDB_KEEP_CACHE_SIZEto at least 50M only specifies a separate buffer pool for objects with the KEEP cache attribute and does not affect Big Table caching.
* E:andF:Changing thePARALLEL_DEGREE_POLICYtoADAPTIVEorAUTOinfluences the behavior of parallel execution but does not directly enable or influence Big Table caching.
References:
* Oracle Database Performance Tuning Guide:Big Table Caching
* Oracle Database Reference:DB_BIG_TABLE_CACHE_PERCENT_TARGET
* Oracle Database Reference:DB_CACHE_SIZE
NEW QUESTION # 29
Which two statements are true about session wait information contained in v$session or v$session_wait?
- A. Rows for sessions that are not waiting always contain the total wait time since the session started.
- B. Rows for sessions that are not waiting might contain the actual wait time for the last event for which they waited.
- C. Rows for sessions that are currently waiting have their wait time incremented every microsecond.
- D. Rows for sessions displaying WAITED UNKNOWN TIME in the STATE column indicate that the session is still waiting.
- E. Rows for sessions that are currently waiting have a wait time of 0.
Answer: B,E
Explanation:
In theV$SESSIONview, Oracle provides information about the session waits:
B: When theWAIT_TIMEcolumn has a value of 0, it signifies that the session is currently waiting for a resource. This column represents the duration of the current or last wait.
C: If the session is not actively waiting, theWAIT_TIMEcolumn shows the time the session spent waiting for the last wait event. If theSTATEcolumn is showing "WAITED KNOWN TIME", it means the session is not currently waiting, but it indicates the time for which it had waited.
References:
* Oracle Database Reference, 19c
* Oracle Database Performance Tuning Guide, 19c
NEW QUESTION # 30
Which two statements are true about space usage in temporary tablespaces?
- A. Lack of temporary tablespace space for sort operations can be prevented by using temporary tablespace groups.
- B. When a global temporary table instantiation is too large to fit in memory, space is allocated in a temporary tablespace.
- C. Temporary tablespaces setting Includes quotas to limit temporary space used by a session for that Temporary tablespace.
- D. A sort will fail if a sort to disk requires more disk space and no additional extent can be found/allocated in/for the sort segment.
- E. When a session consumes all temporary tablespace storage, then the session would hang until the temporary space used by that session is cleared.
Answer: A,B
Explanation:
Regarding space usage in temporary tablespaces, the following statements are true:
* A (Correct):When a global temporary table or a sort operation exceeds the available memory, Oracle Database allocates space in a temporary tablespace to store the temporary data or intermediate results.
* E (Correct):Using temporary tablespace groups can prevent insufficient temporary tablespace for sort operations by providing a collective pool of space from multiple temporary tablespaces, which can be used for user sorting operations.
The other options provided have inaccuracies:
* B (Incorrect):Oracle does not provide a mechanism for setting quotas on temporary tablespaces. Quotas can be set for permanent tablespaces but not for temporary ones.
* C (Incorrect):A sort operation may fail due to insufficient space, but Oracle will attempt to allocate space in the temporary tablespace dynamically. If no space can be allocated, an error is returned rather than a sort failure.
* D (Incorrect):If a session consumes all available temporary tablespace storage, Oracle will not hang the session; it will return an error to the session indicating that it has run out of temporary space.
References:
* Oracle Database Administrator's Guide:Managing Space for Schema Objects
* Oracle Database Concepts:Temporary Tablespaces
NEW QUESTION # 31
You need to collect and aggregate statistics for the ACCTG service and PAYROLL module, and execute:
Where do you find the output of this command?
- A. In the current working directory
- B. By viewing V$SERVICE_STATS
- C. In $ORACLE_BASE/diag/rdbms/<db unique name>/<instance name>/trace
- D. By viewing V$SERV_MOD_ACT_STATS
Answer: D
Explanation:
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 theV$SERV_MOD_ACT_STATSdynamic 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 (
$ORACLE_BASE/diag), the aggregated statistics for services and modules are not written to trace files but are instead viewable through dynamic performance views.
* C (Incorrect):TheV$SERVICE_STATSview 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
NEW QUESTION # 32
Which Optimizer component helps decide whether to use a nested loop join or a hash join in an adaptive execution plan?
- A. Statistics Feedback
- B. Automatic Reoptimization
- C. Statistics Collector
- D. Dynamic Statistics
- E. SQL Plan Directives
Answer: C
Explanation:
In an adaptive execution plan, the Optimizer makes runtime decisions between nested loop and hash joins using a statistics collector. The collector is a row source that collects statistics about the rows it processes and can adapt the plan based on the number of rows processed.
References:
* Oracle Database SQL Tuning Guide, 19c
NEW QUESTION # 33
A database supporting a mixed workload is hosted on a server with 64 CPUs.
A large number of free buffer waits and buffer busy waits occur affecting performance.
The buffer cache size was then increased but after a few hours, the same wait events occur more often than before the change.
Examine these parameter settings:
Which two actions can help reduce the number of these waits7
- A. setting dbwr_io_slaves to 64
- B. increasing the value of DBWRITERPROCESSES to 64,
- C. Increasing the size of MEMORYTARGET
- D. increasing the value of DB_FILE_MULTIBLOCK_READ_COUNT to 128
- E. reducing the values of DB_FILE_MULTILOCK_READ_COUNT to 64
Answer: A,B
Explanation:
Given a server with 64 CPUs, if the buffer cache size increase did not alleviate free buffer waits and buffer busy waits, one can look into optimizing I/O and the efficiency of the DB writer processes.
C: Setting the DBWR_IO_SLAVES parameter to a non-zero value, such as the number of CPUs, would initiate I/O slave processes to assist the DB writer process. This can help reduce I/O contention when writing from the buffer cache to disk, particularly for systems without asynchronous I/O capabilities.
D: Increasing the value of DBWRITERPROCESSES enables multiple DB writer processes to be active simultaneously. In a system with many CPUs, such as 64, increasing this value can improve the write throughput to disk and potentially reduce buffer busy waits.
References:
* Oracle Database Reference, 19c
* Oracle Database Performance Tuning Guide, 19c
NEW QUESTION # 34
A database supporting a mixed workload is hosted on a server with 64 CPUs.
A large number of free buffer waits and buffer busy waits occur affecting performance.
The buffer cache size was then increased but after a few hours, the same wait events occur more often than before the change.
Examine these parameter settings:
Which two actions can help reduce the number of these waits7
- A. setting dbwr_io_slaves to 64
- B. increasing the value of DBWRITERPROCESSES to 64,
- C. Increasing the size of MEMORYTARGET
- D. increasing the value of DB_FILE_MULTIBLOCK_READ_COUNT to 128
- E. reducing the values of DB_FILE_MULTILOCK_READ_COUNT to 64
Answer: A,B
Explanation:
Given a server with 64 CPUs, if the buffer cache size increase did not alleviate free buffer waits and buffer busy waits, one can look into optimizing I/O and the efficiency of the DB writer processes.
C: Setting theDBWR_IO_SLAVESparameter to a non-zero value, such as the number of CPUs, would initiate I/O slave processes to assist the DB writer process. This can help reduce I/O contention when writing from the buffer cache to disk, particularly for systems without asynchronous I/O capabilities.
D: Increasing the value ofDBWRITERPROCESSESenables multiple DB writer processes to be active simultaneously. In a system with many CPUs, such as 64, increasing this value can improve the write throughput to disk and potentially reduce buffer busy waits.
References:
* Oracle Database Reference, 19c
* Oracle Database Performance Tuning Guide, 19c
NEW QUESTION # 35
Examine this statement and output:
Which two situations can trigger this error?
- A. There is a file in the capture directory.
- B. The instance is unable to access the capture directory.
- C. The user lacks the required privileges to execute the DBMS WORKLOAD CAPTURE package or the directory.
- D. The capture directory is part of the root file system.
- E. The syntax is incomplete.
Answer: B,C
Explanation:
The ORA-15505 error indicates that the instance encountered errors while trying to access the specified directory. This could be due to:
A: Insufficient privileges: The user attempting to start the workload capture might not have the required permissions to execute the DBMS_WORKLOAD_CAPTURE package or to read/write to the directory specified.
E: Accessibility: The database instance may not be able to access the directory due to issues such as incorrect directory path, directory does not exist, permission issues at the OS level, or the directory being on a file system that's not accessible to the database instance.
References:
* Oracle Database Error Messages, 19c
* Oracle Database Administrator's Guide, 19c
NEW QUESTION # 36
You must write a statement that returns the ten most recent sales. Examine this statement:
Users complain that the query executes too slowly. Examine the statement's current execution plan:
What must you do to reduce the execution time and why?
- A. Replace the FETCH FIRST clause with ROWNUM to enable the use of an index on SALES.
- B. Enable Adaptive Plans so that Oracle can change the Join method as well as the Join order for this query.
- C. Collect a new set of statistics on PRODUCT, CUSTOMERS, and SALES because the current stats are inaccurate.
- D. Create an index on SALES.TIME_ID to force the return of rows in the order specified by the ORDER BY clause.
- E. Create an index on SALES.CUST_ID to force an INDEX RANGE SCAN on this index followed by a NESTED LOOP join between CUSTOMERS and SALES.
Answer: D
Explanation:
The execution plan shows a full table access for the SALES table. To reduce the execution time, creating an index on SALES.TIME_ID would be beneficial as it would allow the database to quickly sort and retrieve the most recent sales without the need to perform a full table scan, which is I/O intensive and slower. By indexing TIME_ID, which is used in the ORDER BY clause, the optimizer can take advantage of the index to efficiently sort and limit the result set to the ten most recent sales.
* B (Incorrect): Replacing FETCH FIRST with ROWNUM would not necessarily improve the performance unless there is an appropriate index that the optimizer can use to avoid sorting the entire result set.
* C (Incorrect): There is no indication that the current statistics are inaccurate; hence, collecting new statistics may not lead to performance improvement.
* D (Incorrect): While adaptive plans can provide performance benefits by allowing the optimizer to adapt the execution strategy, the main issue here is the lack of an index on the ORDER BY column.
* E (Incorrect): Creating an index on SALES.CUST_ID could improve join performance but would not address the performance issue caused by the lack of an index on the ORDER BY column.
References:
* Oracle Database SQL Tuning Guide: Managing Indexes
* Oracle Database SQL Tuning Guide: Using Indexes and Clusters
NEW QUESTION # 37
Multiple sessions are inserting data concurrently into a table that has an LOB column.
At some point in time, one of the sessions cannot find available space in the LOB segment and needs to allocate a new extent.
Which wait event will be raised in the other sessions that need space in the LOB column?
- A. enq: SQ - contention
- B. enq: HW - contention
- C. enq: TX - allocate ITL entry
- D. enq: TM - contention
Answer: B
Explanation:
When sessions concurrently insert data into a table with an LOB column and one session needs to allocate a new extent because it cannot find available space, the wait event associated with this contention is "enq: HW - contention". The HW stands for High Water Mark which is related to space allocation in the database segment. When a session needs to allocate a new extent, it may raise this wait event in other sessions that are also attempting to allocate space in the same LOB segment.
References
* Oracle Database 19c Reference Guide - enq: HW - contention
NEW QUESTION # 38
Examine these commands, which execute successfully:
Which statement is true?
- A. ADDM, AWR, and ASH reports can be purged automatically.
- B. AWR- snapshots in all pluggable databases will be purged automatically after every 60 mins.
- C. AD DM is enabled for all pluggable databases.
- D. AWR snapshots can be purged manually in pluggable databases.
Answer: D
Explanation:
The DBMS_WORKLOAD_REPOSITORY.MODIFY_SNAPSHOT_SETTINGS procedure allows
setting attributes related to AWR snapshots. While the interval setting controls the frequency of snapshot generation, purging them is a separate process that can be managed either automatically (with retention settings) or manually.References:
* Oracle Database PL/SQL Packages and Types Reference, 19c
* Oracle Multitenant Administrator's Guide, 19c
NEW QUESTION # 39
Which two Oracle Database features use database services?
- A. Oracle Scheduler
- B. Oracle SQL Tuning Advisor
- C. Oracle SQL Performance Management
- D. Oracle Automatic Reoptimization
- E. Database Resource Manager
Answer: A,E
Explanation:
Database services in Oracle are used to manage how resources are allocated and how workloads are managed within the database. The features that use database services are:
* B (Correct):Database Resource Manager (DBRM) uses services to control resource allocation to different workloads. It ensures that resources are assigned to the most critical tasks first, based on the service associated with the workload.
* E (Correct):Oracle Scheduler can also utilize database services. Jobs in Oracle Scheduler can be assigned to different services to control resource allocation and prioritization.
The other features mentioned are related to SQL performance but do not directly utilize database services in the way Resource Manager and Scheduler do:
* A:Oracle Automatic Reoptimization is a feature that allows the database to automatically improve the execution plan of a SQL statement after it is executed, based on the actual performance metrics, but it does not directly use database services.
* C:Oracle SQL Performance Management involves various components of SQL tuning and monitoring, but it does not use database services to operate.
* D:Oracle SQL Tuning Advisor provides advice on how to tune SQL queries for better performance.
While it can be used in conjunction with services for managing and analyzing workloads, it doesn't use services in its core functionality.
References:
* Oracle Database Administrator's Guide:Administering Services
* Oracle Database Administrator's Guide:Managing Resources with Oracle Database Resource Manager
* Oracle Database Scheduler Developer's Guide:Using the Scheduler
NEW QUESTION # 40
Database performance has degraded recently.
index range scan operations on index ix_sales_time_id are slower due to an increase in buffer gets on sales table blocks.
Examine these attributes displayed by querying DBA_TABLES:
Now, examine these attributes displayed by querying DBA_INDEXES:
Which action will reduce the excessive buffer gets?
- A. Re-create the SALES table using the columns in IX_SALES_TIME_ID as the hash partitioning key.
- B. Re-create index IX_SALES_TIME_ID using ADVANCED COMPRESSION.
- C. Partition index IX_SALES_TIME_ID using hash partitioning.
- D. Re-create the SALES table sorted in order of index IX_SALES_TIME_ID.
Answer: B
Explanation:
Given that index range scan operations onIX_SALES_TIME_IDare slower due to an increase in buffer gets, the aim is to improve the efficiency of the index access. In this scenario:
* B (Correct):Re-creating the index usingADVANCED COMPRESSIONcan reduce the size of the index, which can lead to fewer physical reads (reduced I/O) and buffer gets when the index is accessed, as more of the index can fit into memory.
The other options would not be appropriate because:
* A (Incorrect):Re-creating theSALEStable sorted in order of the index might not address the issue of excessive buffer gets. Sorting the table would not improve the efficiency of the index itself.
* C (Incorrect):Using the columns inIX_SALES_TIME_IDas a hash partitioning key for theSALES table is more relevant to data distribution and does not necessarily improve index scan performance.
* D (Incorrect):Hash partitioning the index is generally used to improve the scan performance in a parallel query environment, but it may not reduce the number of buffer gets in a single-threaded query environment.
References:
* Oracle Database SQL Tuning Guide:Managing Indexes
* Oracle Database SQL Tuning Guide:Index Compression
NEW QUESTION # 41
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