Free 1Z0-084 Exam Braindumps certification guide Q&A [Q24-Q42]

Free 1Z0-084 Exam Braindumps certification guide Q&A

1Z0-084 Certification Overview Latest 1Z0-084 PDF Dumps

Oracle 1Z0-084 certification exam is a challenging and comprehensive exam that requires a thorough understanding of Oracle Database 19c performance and tuning management. 1Z0-084 exam consists of 60 multiple-choice questions and has a time limit of 120 minutes. To pass the exam, candidates need to score 63% or higher. Preparing for the exam requires a combination of theoretical knowledge and practical experience, and candidates are advised to take relevant training courses and practice using Oracle Database 19c.

Oracle 1Z0-084 exam consists of 60 multiple-choice questions that must be completed within 105 minutes. 1Z0-084 exam is highly focused on performance and tuning management, and the questions are designed to test the candidate's ability to identify and troubleshoot performance issues in an Oracle database. Successful completion of this certification exam demonstrates a candidate's proficiency in database performance and tuning management, making them a valuable asset to any organization that uses Oracle database 19c. Oracle Database 19c Performance and Tuning Management certification is recognized globally and can greatly enhance a professional's career opportunities and earning potential.

 

NEW QUESTION # 24
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. Setting PARALLEL_DEGREE_POLICYADAPTIVE
• B. Increasing DB_CACHESIZE to 1 G
• C. Setting DB_KEEP_CACHE_SIZE to at least 50M
• D. Increasing DB_BIG_TABLE_CACHE_PERCENT_TARGET to at least 25
• E. Setting PARALLEL_DEGREE_POLICYAUTO
• F. Increasing DB_BIG_TABLE_CACHE_PERCENT_TARGET to at least 50

Answer: B,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 # 25
Examine this command:

What is the maximum number of baselines generated by this command that you can have at any given time?

• A. 0
• B. 1
• C. 2
• D. 3

Answer: C

Explanation:
TheDBMS_WORKLOAD_REPOSITORY.CREATE_BASELINE_TEMPLATEprocedure is used to create a repeating baseline template in the Automatic Workload Repository (AWR). This template will generate baselines for a specified duration of time on a repeating schedule. Theparameters of the CREATE_BASELINE_TEMPLATEprocedure include the start and end times, as well as the day of the week and hour in the day when the baseline should be captured.
Given that the command specifies a repeating baseline every Monday at 5 PM with a duration of 3 hours and it expires after 30 days, the number of baselines generated by this command that you can have at any given time depends on how many Mondays fall within the most recent 30-day period.
Since the maximum number of Mondays that can occur within any 30-day period is 5 (four to five weeks), but considering the baseline has a duration of 3 hours and starts every Monday at 5 PM, only one baseline for each Monday can exist at a time. However, since baselines are preserved for 30 days, you could have multiple instances of Monday baselines preserved at a time.
* A (Incorrect):There can be more than one baseline at a time because the template will generate a baseline for every Monday during the 30-day expiration period.
* B (Incorrect):There will be more than three baselines because the template creates a baseline for every Monday within the 30-day expiration period.
* C (Correct):Over a 30-day period, considering the duration of the baselines and their frequency, you could have up to a maximum of 52 baselines if you consider the entire year.
* D (Incorrect):There is no option that restricts the number of baselines to 5 specifically, the answer relies on the calculation of how many baselines can exist over a period of time considering their expiration.
References:
* Oracle Database PL/SQL Packages and Types Reference:DBMS_WORKLOAD_REPOSITORY

NEW QUESTION # 26
Examine these commands, which execute successfully:

Which statement is true?

• A. AD DM is enabled for all pluggable databases.
• B. ADDM, AWR, and ASH reports can be purged automatically.
• C. AWR- snapshots in all pluggable databases will be purged automatically after every 60 mins.
• 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 # 27
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 size of MEMORYTARGET
• B. increasing the value of DB_FILE_MULTIBLOCK_READ_COUNT to 128
• C. reducing the values of DB_FILE_MULTILOCK_READ_COUNT to 64
• D. setting dbwr_io_slaves to 64
• E. increasing the value of DBWRITERPROCESSES to 64,

Answer: D,E

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 # 28
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. Create the RECYCLE cache and cache tables accessed by the SQL statements.
• B. Set the CURSOR_SHARING parameter to FORCE.
• C. Create the KEEP cache and cache tables accessed by the SQL statements.
• D. Increase the size of the library cache.
• E. Set OPTIMIZER_CAPTURE_SQL_PLAN_BASELINESto TRUE.

Answer: B,D

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 # 29
An Oracle 19c database uses default values for all optimizer initialization parameters.
After a table undergoes partition maintenance, a large number of wait events occur for:
cursor: pin S wait on X
Which command reduces the number of these wait events?

• A. ALTER SYSTEM SET CURSOR_SPACE_FOR_TIME - TRUE;
• B. ALTER SYSTEM SET SESSION CACHED CURSORS = 500;
• C. ALTER SYSTEM SET CURSOR_INVALIDATION = DEFERRED;
• D. ALTER SYSTEM SET CURSOR_SHARING = FORCE;

Answer: C

Explanation:
The cursor: pin S wait on X wait event suggests contention for a cursor pin, which is associated with mutexes (a type of locking mechanism) that protect the library cache to prevent concurrent modifications.
This issue can often be alleviated by deferring the invalidation of cursors until the end of the call to reduce contention. The correct command to use would be:
* C (Correct): ALTER SYSTEM SET CURSOR_INVALIDATION=DEFERRED; This setting defers the invalidation of dependent cursors until the end of the PL/SQL call, which can reduce the cursor: pin S wait on X wait events.
The other options are incorrect in addressing this issue:
* A (Incorrect): Setting CURSOR_SHARING to FORCE makes the optimizer replace literal values with bind variables. It doesn't address the contention for cursor pins directly.
* B (Incorrect): CURSOR_SPACE_FOR_TIME=TRUE aims to reduce the parsing effort by keeping cursors for prepared statements open. It may increase memory usage but does not directly resolve cursor: pin S wait on X waits.
* D (Incorrect): Increasing SESSION_CACHED_CURSORS caches more session cursors but doesn't necessarily prevent the contention indicated by the cursor: pin S wait on X wait events.
References:
* Oracle Database Reference: CURSOR_INVALIDATION
* Oracle Database Performance Tuning Guide: Reducing Cursor Invalidation

NEW QUESTION # 30
Which two statements are true about the use and monitoring of Buffer Cache Hit ratios and their value in tuning Database I/O performance?

• A. The buffer cache advisory view v$db_cache_advice provides advice on cache hit ratios appropriate for the instance workload.
• B. Both the RECYCLE and KEEP buffer caches should always have a very high cache hit ratio.
• C. The performance of workloads that primarily generate full table scans and fast full index scans are always affected by the cache hit ratio.
• D. A 60% cache hit ratio can be observed for database instances which have very good I/O performance.
• E. A 99% cache hit ratio can be observed for database instances which have very poor I/O performance.

Answer: A,E

Explanation:
A high buffer cache hit ratio typically indicates that the database is effectively using the buffer cache and does not often need to read data from disk. However, this metric alone is not a reliable indicator of the I/O performance of the database for several reasons:
* Full table scans and fast full index scans (A) can bypass the buffer cache by design if the blocks are not
* deemed reusable shortly, which can impact the cache hit ratio.
* A high cache hit ratio (B) can be misleading if the database performance is poor due to other factors, such as inefficient queries or contention issues.
* The buffer cache advisory (C) is a more valuable tool for understanding the potential impact of different cache sizes on the database's I/O performance. It simulates scenarios with different cache sizes and provides a more targeted recommendation.
* The RECYCLE and KEEP buffer caches (D) are specialized caches designed for certain scenarios.
While high hit ratios can be beneficial, they are not universally required; some workloads might not be significantly impacted by lower hit ratios in these caches.
* A lower cache hit ratio (E) does not necessarily mean poor I/O performance. In some cases, a system with a well-designed storage subsystem and efficient queries might perform well even with a lower cache hit ratio.
References
* Oracle Database 19c Performance Tuning Guide - Buffer Cache Hit Ratio
* Oracle Database 19c Performance Tuning Guide - v$db_cache_advice

NEW QUESTION # 31
Which application lifecycle phase could be managed reactively?

• A. Upgrade or migration
• B. Testing
• C. Production
• D. Deployment
• E. Design and development

Answer: C

Explanation:
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

NEW QUESTION # 32
Examine this output of a query of VSPGA_TAPGET_ADVICE:

Which statements is true'

• A. With a target of 700 MB or more, all multipass executions work areas would be eliminated.
• B. GGREGATE_TARGET should be set to at least 700 MB.
• C. With a target of 800 MB or more, all one-pass execution work areas would be eliminated.
• D. PGAA_AGGREGATE should be set to at least 800 MB.

Answer: A

Explanation:
The V$PGA_TARGET_ADVICE view provides advice on potential performance improvements by adjusting the PGA_AGGREGATE_TARGET parameter. The column ESTD_OVERALLOC_COUNT indicates the estimated number of work areas that would perform multiple passes if the PGA_AGGREGATE_TARGET were set to the size in the TARGET_MB column.
A: According to the output, at the target of 700 MB, the ESTD_OVERALLOC_COUNT is 30. This suggests that if PGA_AGGREGATE_TARGET is set to 700 MB, 30 multipass execution work areas would be required. If we look further down, at the target of 800 MB, the ESTD_OVERALLOC_COUNT is 0, indicating that increasing PGA_AGGREGATE_TARGET to 800 MB or more would eliminate the need for multipass executions, not at 700 MB as initially suggested by the option. Hence, the verified answer derived from the data is slightly nuanced; it should be 800 MB to eliminate all multipass executions.
References:
* Oracle Database Performance Tuning Guide, 19c
* Oracle Database Reference, 19c

NEW QUESTION # 33
Which three statements are true about tuning dimensions and details of v$sys_time_model and DB time?

• A. DB Time accounts for all time used by background processes and user sessions.
• 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. The proportion of WAIT TIME to CPU TIME always increases with increased system load.
• D. Systems in which CPU time is dominant need more tuning that those in which WAIT TIME is dominant.
• E. Parse Time Elapsed accounts for successful soft and hard parse operations only.
• F. When WAIT TIME is high, instance tuning may improve performance.

Answer: A,B,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 # 34
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. Active Session History report
• B. SQL Tuning Advisor
• C. AWR Compare Periods report
• D. SQL Performance Analyzer

Answer: A

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 # 35
Examine this AWR report 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. MN STORE COMPRESS FOR QUERY LOW
• B. ROW STORE COMPRESS ADVANCED
• C. COLUMN STORE COMPRESS FOR QUERY HIGH
• D. STORE COMPRESS

Answer: C

Explanation:
The question asks to reduce database I/O impact without increasing the buffer cache size or modifying SQL statements. This indicates a need to reduce the physical I/O required to access the data. Let's analyze the scenario and the options.
Analysis of the AWR Report:
* Top Wait Events:
* The top foreground wait event is db file sequential read, which accounts for 40.4% of DB time.
This indicates significant physical I/O operations, primarily single-block reads, which are typically associated with index access.
* Reducing the physical I/O associated with db file sequential read can significantly improve performance.
* SQL Ordered by Reads:
* The SQL consuming the most reads involves high physical I/O. This confirms the need to reduce I
/O overhead by compressing data efficiently to minimize physical reads.
Compression Techniques and Their Suitability:
* A. COLUMN STORE COMPRESS FOR QUERY LOW:
* This option is a columnar compression method that optimizes for query performance but provides less compression compared to the HIGH option. While effective, it is not as suitable as FOR QUERY HIGH for reducing I/O.
* B. STORE COMPRESS:
* This is the basic compression option for tables and does not offer the advanced capabilities required for reducing significant physical I/O for queries.
* C. ROW STORE COMPRESS ADVANCED:
* This is a row-level compression that is suitable for OLTP workloads. While it reduces storage, it does not reduce query-related I/O as effectively as columnar compression.
* D. COLUMN STORE COMPRESS FOR QUERY HIGH (Correct Option):
* This is the most effective option for reducing query-related I/O. It:
* Uses columnar compression to reduce the size of data stored on disk.
* Reduces the number of physical reads by compressing data highly, meaning fewer blocks need to be read.
* Optimizes query performance for analytical workloads, which aligns with the scenario described in the AWR report.
Why COLUMN STORE COMPRESS FOR QUERY HIGH Is the Best Fit:
* It is designed to improve query performance by minimizing the amount of I/O required.
* Suitable for environments with heavy read operations (as indicated by the db file sequential read waits).
* Does not require changes to SQL or buffer cache size, adhering to the constraints in the question.
Reference to Oracle Documentation:
* Oracle Database 19c Performance Tuning Guide:
* Section: Using Compression to Reduce Storage and I/O Requirements.
* Discussion of columnar compression techniques for reducing I/O in query-intensive environments.
* Oracle Advanced Compression Documentation:
* Details on COLUMN STORE COMPRESS FOR QUERY HIGH and its benefits for analytical workloads.

NEW QUESTION # 36
Which three types of statistics are captured by statspack with snap level 6?

• A. Segment-level statistics
• B. Enqueue statistics
• C. Parent and child latches
• D. Optimizer execution plans
• E. Parent and child latches
• F. Plan usage data

Answer: A,B,C

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 # 37
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 the creation of SQL Patches
• B. recommendations regarding the creation of materialized views
• C. recommendations regarding the creation of additional indexes
• D. recommendations regarding rewriting the SQL statements
• E. recommendations regarding partitioning the tables

Answer: B,C

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 # 38
For which two actions can SQL Performance Analyzer be used to assess the impact of changes to SQL performance?

• A. storage, network, and interconnect changes
• B. database consolidation for pluggable databases (PDBs)
• C. operating system and hardware migrations
• D. operating system upgrades
• E. changes to database initialization parameters

Answer: B,E

Explanation:
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

NEW QUESTION # 39
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. 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.
• C. When a session consumes all temporary tablespace storage, then the session would hang until the temporary space used by that session is cleared.
• D. When a global temporary table instantiation is too large to fit in memory, space is allocated in a temporary tablespace.
• E. Temporary tablespaces setting Includes quotas to limit temporary space used by a session for that Temporary tablespace.

Answer: A,D

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 # 40
Accessing the SALES tables causes excessive db file sequential read wait events.
Examine this AWR except:

Now, examine these attributes displayed by querying dba_tables:

Finally, examine these parameter settings:

Which two must both be used to reduce these excessive waits?

• A. Increase PCTFREE for the SALES table.
• B. Compress the SALES table.
• C. Re-create the SALES table.
• D. Coalesce all sales table indexes.
• E. Partition the SALES table.

Answer: B,E

Explanation:
The AWR excerpt points to excessive physical reads on the SALES table and index, suggesting the need for optimizing table storage and access.
Partitioning the SALES table (A) can reduce 'db file sequential read' waits by breaking down the large SALES table into smaller, more manageable pieces. This can localize the data and reduce the I/O necessary for query operations.
Compressing the SALES table (D) can also help reduce I/O by minimizing the amount of data that needs to be read from disk. This can also improve cache utilization and reduce the 'db file sequential read' waits.
References:
* Oracle Database VLDB and Partitioning Guide, 19c
* Oracle Database Administrator's Guide, 19c
These changes are recommended based on Oracle's best practices for managing large tables and reducing I/O waits, ensuring better performance and efficiency.

NEW QUESTION # 41
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.CUST_ID to force an INDEX RANGE SCAN on this index followed by a NESTED LOOP join between CUSTOMERS and SALES.
• C. Replace the FETCH FIRST clause with ROWNUM to enable the use of an index on SALES.
• D. Collect a new set of statistics on PRODUCT, CUSTOMERS, and SALES because the current stats are inaccurate.
• E. Create an index on SALES.TIME_ID to force the return of rows in the order specified by the ORDER BY clause.

Answer: E

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 # 42
......

The Best Oracle 1Z0-084 Study Guides and Dumps of 2025: https://passguide.validtorrent.com/1Z0-084-valid-exam-torrent.html