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Oracle 1Z0-084 certification exam is a valuable credential for professionals seeking to prove their expertise in managing the performance and tuning of Oracle Database 19c. It demonstrates their ability to optimize the performance of the database and ensure that it runs smoothly and efficiently. Oracle Database 19c Performance and Tuning Management certification also shows that they understand how to identify and resolve performance issues quickly and effectively.
Oracle 1Z0-084 Certification Exam is an excellent way for database professionals to demonstrate their expertise in performance and tuning management. By passing 1z1-084 exam, candidates can prove to potential employers that they possess the knowledge and skills needed to manage and optimize Oracle Database 19c performance. Additionally, earning this certification can lead to career advancement opportunities and higher salaries.
Oracle 1Z0-084 exam is an excellent opportunity for IT professionals to validate their skills and knowledge in Oracle Database 19c Performance and Tuning Management. 1z1-084 exam is challenging and requires candidates to have a deep understanding of performance tuning methodologies and database management. However, with proper preparation and practice, candidates can pass the exam and enhance their career prospects in the field of database management.
NEW QUESTION # 32
Database performance degraded between 23:15 and 23:30 for the last three nights. The awr snapshot interval is one hour. The AODM report contains nothing about this performance problem.
With which tool can you further analyze this problem?
- A. AWR Compare Periods report
- B. Active Session History report
- C. SQL Tuning Advisor
- D. SQL Performance Analyzer
Answer: B
Explanation:
The Active Session History (ASH) report is a tool that provides detailed information about active sessions for the time period specified. Since the AWR snapshot interval is one hour and does not capture the granularity needed for this issue, ASH reports aremore suitable as they contain more granular data for sessions that were active during the period of interest.
References:
* Oracle Database Performance Tuning Guide, 19c
NEW QUESTION # 33
Which two options are part of a Soft Parse operation?
- A. SQL Row Source Generation
- B. Semantic Check
- C. SQL Optimization
- D. Shared Pool Memory Allocation
- E. Syntax Check
Answer: B
NEW QUESTION # 34
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. Enable Adaptive Plans so that Oracle can change the Join method as well as the Join order for this query.
- B. Create an index on SALES.TIME_ID to force the return of rows in the order specified by the ORDER BY clause.
- C. Replace the FETCH FIRST clause with ROWNUM to enable the use of an index on SALES.
- D. 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.
- E. Collect a new set of statistics on PRODUCT, CUSTOMERS, and SALES because the current stats are inaccurate.
Answer: B
Explanation:
The execution plan shows a full table access for theSALEStable. To reduce the execution time, creating an index onSALES.TIME_IDwould 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 theORDER BYclause, the optimizer can take advantage of the index to efficiently sort and limit the result set to the ten most recent sales.
* B (Incorrect):ReplacingFETCH FIRSTwithROWNUMwould 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 theORDER BYcolumn.
* E (Incorrect):Creating an index onSALES.CUST_IDcould improve join performance but would not address the performance issue caused by the lack of an index on theORDER BYcolumn.
References:
* Oracle Database SQL Tuning Guide:Managing Indexes
* Oracle Database SQL Tuning Guide:Using Indexes and Clusters
NEW QUESTION # 35
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 the SALES table sorted in order of index IX_SALES_TIME_ID.
- C. Partition index IX_SALES_TIME_ID using hash partitioning.
- D. Re-create index IX_SALES_TIME_ID using ADVANCED COMPRESSION.
Answer: D
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 # 36
Which two options are part of a Soft Parse operation?
- A. SQL Row Source Generation
- B. Syntax Check
- C. Semantic Check
- D. SQL Optimization
- E. Shared Pool Memory Allocation
Answer: B,C
Explanation:
What is a Soft Parse?
A Soft Parse occurs when a SQL statement is already present in the shared SQL area (Shared Pool) of the database. Instead of recreating the execution plan, Oracle reuses the existing plan, making the process much faster and more efficient. This is an essential optimization step in Oracle Database to reduce overhead and improve performance.
Steps Involved in a Soft Parse
* Syntax Check (Step A)
* This is the first step of the parsing process.
* Purpose: Ensures the SQL statement conforms to proper syntax rules defined by the SQL language.
* Example:
SELECT FROM employees;
This query will fail at the Syntax Check step because it doesn't specify any columns to retrieve. Oracle ensures that such malformed queries are identified early.
* Semantic Check (Step E)
* The Semantic Check happens after the Syntax Check if the statement passes the syntax validation.
* Purpose:
* Verify Object Existence: Check if all referenced tables, columns, and other database objects exist. Example:
SELECT salary FROM non_existent_table;
This query will fail because the table non_existent_table does not exist.
* User Privileges: Ensure the user has sufficient permissions to access the objects. Example:
SELECT * FROM employees;
If the user doesn't have SELECT privileges on the employees table, the query will fail.
* Validate Data Types: Ensure that columns used in expressions or comparisons are compatible in terms of data types. Example:
SELECT * FROM employees WHERE hire_date = '01-01-2023';
If hire_date is stored as a DATE type, and the literal is not implicitly convertible, this will fail.
Steps Skipped in a Soft Parse
SQL Row Source Generation (Option B):
This step involves breaking the query into operations (row sources) to fetch data. It is part of execution plan generation, which happens only during a Hard Parse.
SQL Optimization (Option C):
The SQL Optimizer calculates the most efficient execution plan during a hard parse. In a soft parse, the existing plan is reused, so this step is skipped.
Shared Pool Memory Allocation (Option D):
A Hard Parse allocates memory in the shared pool for a new SQL statement. In a soft parse, Oracle reuses the existing shared memory, avoiding additional allocation.
Why Are Syntax Check and Semantic Check the Correct Steps?
These steps are mandatory validations for all SQL statements, even during a soft parse. Without them, Oracle would risk executing invalid or unauthorized SQL statements.
By reusing the execution plan but performing these lightweight checks, Oracle ensures both efficiency and correctness.
References to Oracle Database 19c: Performance Management and Tuning
Oracle Documentation:
Oracle Database 19c Concepts: SQL Parsing and Execution
Oracle Database Performance Tuning Guide: Understanding Hard Parses and Soft Parses Key Features Discussed in the Guide:
Shared Pool and Library Cache: The role of the shared SQL area in reducing parsing overhead.
SQL Execution Workflow: Detailed explanation of syntax and semantic checks.
SQL Optimizer: The differences between hard and soft parsing in relation to the optimizer.
Tools for Analysis:
AWR Reports: Monitor the number of hard vs. soft parses for query performance.
V$SQL: View cached SQL statements and their parsing statistics.
NEW QUESTION # 37
Which two options are part of a Soft Parse operation?
- A. SQL Row Source Generation
- B. Semantic Check
- C. SQL Optimization
- D. Shared Pool Memory Allocation
- E. Syntax Check
Answer: B
Explanation:
During a soft parse, Oracle checks the shared SQL area to see if an incoming SQL statement matches one already in the shared pool. This operation includes syntax and semantic checks. The syntax check ensures the statement is properly formed, and the semantic check confirms that all the objects referenced in the SQL statement exist and that the user has the necessary privileges to access them.References:
* Oracle Database Concepts, 19c
* Oracle Database SQL Tuning Guide, 19c
NEW QUESTION # 38
Which statement is true about DB time in V$$YS_TIME_MODEL?
- A. DB time is organized as a simple list of statistics and any time period is attributable to only one statistic.
- B. DB tine excludes the time spent waiting for a CPU in the operating system run queue.
- C. DB time can be many times greater than the elapsed time since the database instance started.
- D. DB time includes the time spent executing the RMAN backup and restore command.
Answer: C
Explanation:
DB time includes the time spent on user and background processes. It can be greater than the elapsed time because it accumulates the active time of all the processes. For example, if two sessions are each active for 2 seconds at the same time, DB time would accumulate 4 seconds, while the elapsed time would be only 2 seconds.References:
* Oracle Database Performance Tuning Guide, 19c
* Oracle Database Reference, 19c
NEW QUESTION # 39
Which two types of performance problems are reported by ADDM for PDBS?
- A. Top SQL statements
- B. User I/O waits
- C. Excessive checkpoint writes
- D. I/O capacity limits
- E. SGA sizing issues
Answer: B,D
Explanation:
The Automatic Database Diagnostic Monitor (ADDM) analyzes and reports on various types of performance problems. For Pluggable Databases (PDBs), it can identify issues such as I/O capacity limits which may hinder the overall performance by causing bottlenecks. Additionally, ADDM can report on user I/O waits, which can indicate performance issues related to the time it takes for user queries to read data from the disk.
References:
* Oracle Multitenant Administrator's Guide, 19c
* Oracle Database Performance Tuning Guide, 19c
NEW QUESTION # 40
A Standard Edition production database has performance problems for two hours on the same day each week.
Which tool must you use to diagnose the problem?
- A. AWR Compare Periods report
- B. Statspack report
- C. SQL Performance Analyzer
- D. Database Replay
Answer: B
Explanation:
For a Standard Edition production database, the Statspack tool is available to diagnose performance problems.
The Automatic Workload Repository (AWR) and its related tools like AWR Compare Periods report and SQL Performance Analyzer are features of the Oracle Database Enterprise Edition and are not available in Standard Edition. Database Replay is also a feature of the Enterprise Edition. Statspack is a performance diagnostic tool provided for earlier versions and Standard Editions of the Oracle Database to collect, store, and analyze performance data.
References
* Oracle Database 19c Administrator's Guide - Using Statspack to Diagnose Database Performance Issues
NEW QUESTION # 41
You must configure and enable Database Smart Flash Cache for a database.
You configure these flash devices:
Examine these parameter settings:
What must be configured so that the database uses these devices for the Database Smart Flash Cache?
- A. Set DB_FLASH_CACHE_SIZE parameter to 192G.
- B. Set DB_FLASH_CACHE_SIZE to 192G and MEMORY_TARGET to 256G.
- C. Set DB_FLASH_CACHE_SIZE parameter to 128G, 64G.
- D. Disable Automatic Memory Management and set SGA_TARGET to 256G.
- E. Set DB_FLASH_CACHE_SIZE to 256G and change device /dev/sdk to 128G.
Answer: C
Explanation:
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 youintend 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
NEW QUESTION # 42
Which Optimizer component helps decide whether to use a nested loop join or a hash join in an adaptive execution plan?
- A. Statistics Collector
- B. SQL Plan Directives
- C. Automatic Reoptimization
- D. Dynamic Statistics
- E. Statistics Feedback
Answer: A
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 # 43
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. Enable Adaptive Plans so that Oracle can change the Join method as well as the Join order for this query.
- B. Create an index on SALES.TIME_ID to force the return of rows in the order specified by the ORDER BY clause.
- C. Replace the FETCH FIRST clause with ROWNUM to enable the use of an index on SALES.
- D. 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.
- E. Collect a new set of statistics on PRODUCT, CUSTOMERS, and SALES because the current stats are inaccurate.
Answer: B
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 # 44
Users complain about slowness and session interruptions. Additional checks reveal the following error in the application log:
Which file has additional information about this error?
- A. SQL trace file automatically generated by the error
- B. Alert log
- C. Session trace file SQL trace file automatically generated by the error
- D. ASH report
Answer: B
Explanation:
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
NEW QUESTION # 45
You are informed that the RMAN session that is performing the database duplication is much slower than usual. You want to know the approximate time when the rman operation will be completed.
Which view has this information?
- A. V$SESSION
- B. V$SESSTAT
- C. V$SESSION_LONGOPS
- D. V$RMAN_BACKUP_JOB_DETAILS
Answer: C
Explanation:
In Oracle Database, theV$SESSION_LONGOPSview provides insights into various operations within the database that are expected to take more than six seconds to complete. These include operations related to RMAN (Recovery Manager), such as database duplication tasks. This view displays information about the progress of these long-running operations, including the start time, elapsed time, and estimated time to completion.
When an RMAN session is performing a database duplication and is observed to be slower than usual, checking theV$SESSION_LONGOPSview can give an approximation ofwhen the RMAN operation might complete. This view includes fields likeTIME_REMAININGandELAPSED_SECONDSthat help in estimating the completion time of the operation based on its current progress.
References:
* Oracle Database Reference:V$SESSION_LONGOPS
* Oracle Database Backup and Recovery User's Guide:Monitoring RMAN Jobs
NEW QUESTION # 46
Which three statements are true about tuning dimensions and details of v$sys_time_model and DB time?
- A. Systems in which CPU time is dominant need more tuning that those in which WAIT TIME is dominant.
- B. Statspack cannot account for high CPU time when CPU TIME is a Top 10 event in DB time. When CPU time is high, SQL tuning may improve performance.
- C. Parse Time Elapsed accounts for successful soft and hard parse operations only.
- D. DB Time accounts for all time used by background processes and user sessions.
- E. The proportion of WAIT TIME to CPU TIME always increases with increased system load.
- F. When WAIT TIME is high, instance tuning may improve performance.
Answer: B,D,F
Explanation:
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
NEW QUESTION # 47
SGA_TARGET and PGA_AGGREGATE_TARGET are configured to nonzero values.
MEMORY_target is then set to a nonzero value but memory_MAX_TARGET is not set.
Which two statements are true?
- A.
- B.
- C.
- D.
- E.
- F.
- G.
Answer: B,D
Explanation:
When MEMORY_TARGET is set to a nonzero value, Oracle automatically manages the memory allocation between the System Global Area (SGA) and the Program Global Area (PGA). If MEMORY_MAX_TARGET is not explicitly set, Oracle will behave in the following manner:
* MEMORY_MAX_TARGET will default to the value of MEMORY_TARGET, assuming the platform allows for the value of MEMORY_TARGET to be increased dynamically. This means that MEMORY_TARGET represents both the initial allocation and the maximum limit for the dynamically managed memory unless MEMORY_MAX_TARGET is specified differently.
* If MEMORY_TARGET is set to a value that is less than the sum of the current values of SGA_TARGET and PGA_AGGREGATE_TARGET, Oracle will use the higher sum as the default value for MEMORY_MAX_TARGET to ensure that there is adequate memory for both areas. The database instance will not start if MEMORY_TARGET is not sufficient to accommodate the combined SGA and PGA requirements.
References
* Oracle Database Administrator's Guide 19c: Automatic Memory Management
* Oracle Database Performance Tuning Guide 19c: Using Automatic Memory Management
NEW QUESTION # 48
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. increasing the value of DB_FILE_MULTIBLOCK_READ_COUNT to 128
- B. reducing the values of DB_FILE_MULTILOCK_READ_COUNT to 64
- C. setting dbwr_io_slaves to 64
- D. increasing the value of DBWRITERPROCESSES to 64,
- E. Increasing the size of MEMORYTARGET
Answer: C,D
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 # 49
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