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Oracle 1Z0-084 certification exam is designed for individuals who want to demonstrate their expertise in managing the performance and tuning of Oracle Database 19c. 1Z0-084 exam is aimed at database administrators, performance analysts, and developers who want to prove their skills in managing and tuning Oracle Database 19c to ensure optimal performance.
Oracle 1Z0-084 Certification Exam covers all aspects of Oracle Database 19c Performance and Tuning Management, including the most effective tuning methodologies, tools, and techniques used to optimize the database performance. 1Z0-084 exam validates a candidate’s ability to identify and understand the underlying problems in a database and provide the best solution to solve them. Oracle Database 19c Performance and Tuning Management certification exam helps professionals to develop their skill set and their ability to effectively tune and optimize databases in any real-world scenario.
NEW QUESTION # 16
Which procedure gathers statistics that are always used in the generation of any execution plan?
- A. DBMS_STATS.GATHER_DICTIONARY_STATS
- B. DBMS_STATS.GATHER_DATABASE_STATS
- C. DBMS_STATS.GATHER_FIXED_ OBJECTS_STATS
- D. DBMS_STATS.GATHER_SYSTEM_STATS
Answer: B
Explanation:
TheDBMS_STATS.GATHER_DATABASE_STATSprocedure is used to gather statistics for all schema objects in the database that do not have up-to-date statistics. These statistics are essential for the optimizer to make informed decisions about the most efficient way to execute a query. The procedure collects statistics such as table and column statistics, index statistics, and system statistics, which are all used in the execution plan generation.
References:
* Oracle Database PL/SQL Packages and Types Reference, 19c
* Oracle Database Performance Tuning Guide, 19c
NEW QUESTION # 17
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. Setting PARALLEL_DEGREE_POLICYADAPTIVE
- C. Setting PARALLEL_DEGREE_POLICYAUTO
- D. Increasing DB_BIG_TABLE_CACHE_PERCENT_TARGET to at least 50
- E. Increasing DB_CACHESIZE to 1 G
- F. Setting DB_KEEP_CACHE_SIZE to at least 50M
Answer: A,E
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_TARGET is 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): Increasing DB_BIG_TABLE_CACHE_PERCENT_TARGET to 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): Increasing DB_CACHE_SIZE to 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: Increasing DB_BIG_TABLE_CACHE_PERCENT_TARGET to 50 without adjusting the overall size of the cache might still not be sufficient if the DB_CACHE_SIZE is not large enough to hold the big tables.
* B: Setting DB_KEEP_CACHE_SIZE to at least 50M only specifies a separate buffer pool for objects with the KEEP cache attribute and does not affect Big Table caching.
* E: and F: Changing the PARALLEL_DEGREE_POLICY to ADAPTIVE or AUTO influences 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 # 18
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. Dynamic Statistics
- C. Statistics Feedback
- D. SQL Plan Directives
- E. Automatic Reoptimization
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 # 19
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 critical alert will be issued when CPU time exceeds 2 minutes for each user call.
- C. A critical alert will be issued when CPU time exceeds 10000 microseconds for each user call.
- D. A warning alert will be issued only when CPU time exceeds 10000 microseconds for each user call.
Answer: C
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 # 20
The CURS0R_SHARING and OPTIMIZER_CAPTURE_SQL_PLAN_BASELINES parameters are set to default. The top five wait events in an awr report are due to a large number of hard parses because of several almost identical SQL statements.
Which two actions could reduce the number of hard parses?
- A. Set the CURSOR_SHARING parameter to FORCE.
- B. Increase the size of the library cache.
- C. Create the RECYCLE cache and cache tables accessed by the SQL statements.
- D. Create the KEEP cache and cache tables accessed by the SQL statements.
- E. Set OPTIMIZER_CAPTURE_SQL_PLAN_BASELINESto TRUE.
Answer: A,B
Explanation:
To reduce the number of hard parses due to several almost identical SQL statements, you can take the following actions:
* C (Correct):Increasing the size of the library cache can help reduce hard parses by providing more
* memory to store more execution plans. This allows SQL statements to be shared more effectively.
* E (Correct):Setting theCURSOR_SHARINGparameter toFORCEwill cause Oracle to replace literals in SQL statements with bind variables, which can significantly reduce the number of hard parses by making it more likely that similar SQL statements will share the same execution plan.
The other options do not directly impact the number of hard parses:
* A (Incorrect):Creating the KEEP cache and caching tables accessed by the SQL statements can improve performance for those tables, but it does not directly reduce the number of hard parses.
* B (Incorrect):Creating the RECYCLE cache and caching tables accessed by the SQL statements can make it more likely that objects will be removed from the cache quickly, which does not help with hard parse issues.
* D (Incorrect):SettingOPTIMIZER_CAPTURE_SQL_PLAN_BASELINEStoTRUEcan help stabilize SQL execution plans but will not reduce the number of hard parses. This parameter is used to automatically capture SQL plan baselines for repeatable SQL statements, which can prevent performance regressions due to plan changes.
References:
* Oracle Database Performance Tuning Guide:Minimizing Hard Parses
* Oracle Database SQL Tuning Guide:CURSOR_SHARING
NEW QUESTION # 21
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$RMAN_BACKUP_JOB_DETAILS
- B. V$SESSION
- C. V$SESSION_LONGOPS
- D. V$SESSTAT
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 # 22
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. Alert log
- B. ASH report
- C. SQL trace file automatically generated by the error
- D. Session trace file SQL trace file automatically generated by the error
Answer: A
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 # 23
Examine this AWRreport excerpt:
You must reduce the impact of database I/O, without increasing buffer cache size and without modifying the SQL statements.
Which compression option satisfies this requirement?
- A. STORE COMPRESS
- B. MN STORE COMPRESS FOR QUERY LOW
- C. COLUMN STORE COMPRESS FOR QUERY HIGH
- D. ROW STORE COMPRESS ADVANCED
Answer: D
Explanation:
To reduce the impact of database I/O without increasing the size of the buffer cache and without modifying SQL statements, you can use table compression. Among the given options,ROW STORE COMPRESS ADVANCEDis the most suitable form of table compression to satisfy this requirement.
Advanced row compression (ROW STORE COMPRESS ADVANCED) is designed to work well with all supported types of data, whether it's OLTP or data warehouse environments. It offers a higher level of compression than basic table compression (ROW STORE COMPRESS BASIC)without significant overhead during DML operations. This feature can help reduce the amount of I/O required to retrieve data by storing it more efficiently on disk.
* A, B, D:WhileCOLUMN STORE COMPRESS FOR QUERY HIGHandROW STORE
COMPRESSare both valid compression types,COLUMN STORE COMPRESS FOR QUERY
* HIGHapplies to the In-Memory column store and is not available in all versions and editions, andROW STORE COMPRESSis less advanced thanROW STORE COMPRESS ADVANCED.
References:
* Oracle Database Concepts Guide:Table Compression
* Oracle Database Performance Tuning Guide:Row Compression
NEW QUESTION # 24
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. SQL Tuning Advisor
- C. Active Session History report
- D. SQL Performance Analyzer
Answer: C
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 # 25
Examine this statement and output:
Which two situations can trigger this error?
- A. The instance is unable to access the capture directory.
- B. There is a file in the capture directory.
- C. The syntax is incomplete.
- D. The user lacks the required privileges to execute the DBMS WORKLOAD CAPTURE package or the directory.
- E. The capture directory is part of the root file system.
Answer: A,D
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 # 26
Examine these commands, which execute successfully:
Which statement is true?
- A. ADDM, AWR, and ASH reports can be purged automatically.
- B. AWR snapshots can be purged manually in pluggable databases.
- C. AWR- snapshots in all pluggable databases will be purgedautomatically after every 60 mins.
- D. AD DM is enabled for all pluggable databases.
Answer: B
Explanation:
TheDBMS_WORKLOAD_REPOSITORY.MODIFY_SNAPSHOT_SETTINGSprocedure 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 # 27
Which two statements are true about space usage in temporary tablespaces?
- A. Temporary tablespaces setting Includes quotas to limit temporary space used by a session for that Temporary tablespace.
- B. Lack of temporary tablespace space for sort operations can be prevented by using temporary tablespace groups.
- C. 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.
- D. When a session consumes all temporary tablespace storage, then the session would hang until the temporary space used by that session is cleared.
- E. When a global temporary table instantiation is too large to fit in memory, space is allocated in a temporary tablespace.
Answer: B,E
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 # 28
Which three types of statistics are captured by statspack with snap level 6?
- A. Optimizer execution plans
- B. Parent and child latches
- C. Parent and child latches
- D. Segment-level statistics
- E. Plan usage data
- F. Enqueue statistics
Answer: C,D,F
Explanation:
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
NEW QUESTION # 29
You want to reduce the amount of db file scattered read that is generated in the database.You execute the SQL Tuning Advisor against the relevant workload. Which two can be part of the expected result?
- A. recommendations regarding partitioning the tables
- B. recommendations regarding rewriting the SQL statements
- C. recommendations regarding the creation of materialized views
- D. recommendations regarding the creation of additional indexes
- E. recommendations regarding the creation of SQL Patches
Answer: C,D
Explanation:
The SQL Tuning Advisor provides recommendations for improving SQL query performance. This may include suggestions for creating additional indexes to speed up data retrieval and materialized views to precompute and store query results.References:
* Oracle Database SQL Tuning Guide, 19c
NEW QUESTION # 30
Which two options are part of a Soft Parse operation?
- A. Semantic Check
- B. Syntax Check
- C. SQL Row Source Generation
- D. Shared Pool Memory Allocation
- E. SQL Optimization
Answer: A,B
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 # 31
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To prepare for the Oracle 1Z0-084 exam, candidates are advised to have a thorough understanding of Oracle Database 19c and its features. They should also have practical experience in performance tuning and management of Oracle databases. Candidates can also take advantage of various online resources, study guides, and practice tests to prepare for the exam.
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