1Z0-084練習試験テスト最新問題2025年08月 [Q26-Q42]

1Z0-084練習試験テスト最新問題2025年08月

1Z0-084試験を一発合格保証問題集！

質問 # 26
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 sorted in order of index IX_SALES_TIME_ID.
• 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 using the columns in IX_SALES_TIME_ID as the hash partitioning key.

正解：B

解説：
Given that index range scan operations on IX_SALES_TIME_ID are 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 using ADVANCED COMPRESSION can 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 the SALES table 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 in IX_SALES_TIME_ID as a hash partitioning key for the SALES 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

質問 # 27
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 to 192G and MEMORY_TARGET to 256G.
• B. Set DB_FLASH_CACHE_SIZE parameter to 192G.
• C. Set DB_FLASH_CACHE_SIZE to 256G and change device /dev/sdk to 128G.
• D. Set DB_FLASH_CACHE_SIZE parameter to 128G, 64G.
• E. Disable Automatic Memory Management and set SGA_TARGET to 256G.

正解：D

解説：
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

質問 # 28
Examine these commands, which execute successfully:

Which statement is true?

• A. AWR- snapshots in all pluggable databases will be purged automatically after every 60 mins.
• B. AD DM is enabled for all pluggable databases.
• C. ADDM, AWR, and ASH reports can be purged automatically.
• D. AWR snapshots can be purged manually in pluggable databases.

正解：D

解説：
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

質問 # 29
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. Plan usage data
• E. Optimizer execution plans
• F. Parent and child latches

正解：A、B、F

解説：
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

質問 # 30
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. With a target of 800 MB or more, all one-pass execution work areas would be eliminated.
• C. PGAA_AGGREGATE should be set to at least 800 MB.
• D. GGREGATE_TARGET should be set to at least 700 MB.

正解：A

解説：
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

質問 # 31
Which two statements are true about disabling Automatic Shared Memory Management (ASMM)?

• A. All SGA components retain their current sizes at the time of disabling.
• B. The SGA size remains unaffected after disabling ASMM.
• C. It requires a database instance restart to take effect.
• D. Both SGA_TARGET and SGA_MAX_SIZE must be set to zero.
• E. All SGA components excluding fixed SGA and other internal allocations are readjusted immediately after disabling ASMM.
• F. All auto-tuned SGA components are reset to their original user-defined values.

正解：A、B

解説：
When ASMM is disabled, the sizes of the automatically managed SGA components remain at their current values. ASMM is controlled by theSGA_TARGETparameter. IfSGA_TARGETis set to a non-zero value, ASMM is enabled and Oracle will automatically manage the sizes of the various SGA components. When ASMM is disabled, by settingSGA_TARGETto zero, the SGA components that were automatically sized will retain their current sizes rather than being reset to their original user-defined values. The overall size of the SGA remains the same unless manually changed by modifying individual component sizes or SGA_MAX_SIZE.
References:
* Oracle Database Administration Guide, 19c
* Oracle Database Performance Tuning Guide, 19c

質問 # 32
What is the right time to stop tuning an Oracle database?

• A. When the buffer cache and library cache hit ratio is above 95%
• B. When all the concurrency waits are eliminated from the Top 10
• C. When the allocated budget for performance tuning has been exhausted
• D. When the I/O is less than 10% of the DB time

正解：C

解説：
The right time to stop tuning an Oracle database is often determined by the point of diminishing returns - when the cost of further tuning (in terms of time, resources, or money) exceeds the performance benefits gained.
This is often related to the budget allocated for performance tuning.
* A (Correct):When the allocated budget for performance tuning has been exhausted, it may be time to stop tuning unless the benefits of further tuning justify requesting additional budget.
* B (Incorrect):Eliminating all concurrency waits from the Top 10 is an unrealistic goal since some waits are inevitable and can occur due to application design, which might not be possible to eliminate completely.
* C (Incorrect):The buffer cache and library cache hit ratio being above 95% does not necessarily indicate that the database is fully optimized. Hit ratios are not reliable indicators of database performance and should not be used as sole criteria to end tuning efforts.
* D (Incorrect):Having I/O less than 10% of DB time is not a definitive indicator to stop tuning. It is essential to consider the overall performance goals and whether they have been met rather than focusing solely on I/O metrics.
References:
* Oracle Database Performance Tuning Guide:Introduction to Performance Tuning
* Oracle Database 2 Day + Performance Tuning Guide:Understanding the Tuning Process

質問 # 33
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=BASIC and CONTROL_MANAGEMENT_PACK ACCESS=DIAGOSTIC
• B. STATISTICS_LEVEL=ALL and
  CONTROL_MANAGEMENT_PACK_ACCESS=DIAGOSTIC+TUNING
• C. STATISTICS_LEVEL=TYPICAL and CONTROL_MANAGEMENT_PACK_ACCESS-
  DIAGOSTIC*TUNING
• D. STATISTICS_LEVEL=TYPICAL and CONTROL_MANAGEMENT_PACK_ACCESS=DIAGOSTIC

正解：B

解説：
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

質問 # 34
Examine this statement and output:

Which three statements are true?

• A. Session 8779 may be waiting due to a network problem.
• B. Session 8779 may be waiting for a user or application response.
• C. Session 9857 waited 1354 seconds for another process, which was also waiting for a transaction to end.
• D. Session 9857 is not waiting.
• E. Session 9822 will always stop waiting if the session that owns the TX enqueue issues a COMMIT statement as session 9822 is the first session in the transaction queue.
• F. Both 9822 and 8779 sessions are waiting for operating system resources.

正解：A、B、E

解説：
For this SQL statement and output, we can analyze theEVENTcolumn to understand the type of wait:
B: The event "SQL*Net message from client" typically indicates that the session is waiting for a response from the client. This can be due to a network issue, user response, or an application processing delay.
E: The event "SQL*Net message from client" also implies that the session is idle waiting for the client (a user or an application) to send a request to the server. This event usually indicates that the session is not actively working but is instead waiting for the next command.
F: The wait event "enq: TX - row lock contention" suggests that session 9822 is waiting for a row-level lock held by another session. If the holding session issues a COMMIT or ROLLBACK, the lock will be released, and session 9822 will stop waiting. Since this session is experiencing row lock contention, it implies it's waiting for a specific transaction to complete.
References:
* Oracle Database Reference, 19c
* Oracle Wait Events Documentation

質問 # 35
Which two statements are true about disabling Automatic Shared Memory Management (ASMM)?

• A. All SGA components retain their current sizes at the time of disabling.
• B. The SGA size remains unaffected after disabling ASMM.
• C. It requires a database instance restart to take effect.
• D. Both SGA_TARGET and SGA_MAX_SIZE must be set to zero.
• E. All SGA components excluding fixed SGA and other internal allocations are readjusted immediately after disabling ASMM.
• F. All auto-tuned SGA components are reset to their original user-defined values.

正解：A、B

解説：
When ASMM is disabled, the sizes of the automatically managed SGA components remain at their current values. ASMM is controlled by the SGA_TARGET parameter. If SGA_TARGET is set to a non-zero value, ASMM is enabled and Oracle will automatically manage the sizes of the various SGA components. When ASMM is disabled, by setting SGA_TARGET to zero, the SGA components that were automatically sized will retain their current sizes rather than being reset to their original user-defined values. The overall size of the SGA remains the same unless manually changed by modifying individual component sizes or SGA_MAX_SIZE.
References:
* Oracle Database Administration Guide, 19c
* Oracle Database Performance Tuning Guide, 19c

質問 # 36
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: TM - contention
• B. enq: TX - allocate ITL entry
• C. enq: HW - contention
• D. enq: SQ - contention

正解：C

解説：
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

質問 # 37
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

正解：B

解説：
The DBMS_WORKLOAD_REPOSITORY.CREATE_BASELINE_TEMPLATE procedure 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. The parameters of the CREATE_BASELINE_TEMPLATE procedure 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

質問 # 38
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: TM - contention
• B. enq: TX - allocate ITL entry
• C. enq: HW - contention
• D. enq: SQ - contention

正解：C

解説：
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 asession 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

質問 # 39
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. MN STORE COMPRESS FOR QUERY LOW
• B. STORE COMPRESS
• C. ROW STORE COMPRESS ADVANCED
• D. COLUMN STORE COMPRESS FOR QUERY HIGH

正解：C

解説：
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

質問 # 40
During which application lifecycle phase do you take baselines?

• A. Production
• B. Migration or upgrade
• C. Testing
• D. Design and development
• E. Deployment

正解：A

解説：
Baselines are typically taken during the production phase of the application lifecycle. They provide a snapshot of performance metrics under normal operating conditions which can be used for comparison against future performance. Baselines are essential for understanding how the system performs under its typical workload and for detecting deviations from this expected performance over time, especially after changes like migrations, upgrades, or significant changes in user activity.
References
* Oracle Database 19c Performance Tuning Guide - Managing Performance Through Baselines

質問 # 41
Which two statements are true about space usage in temporary tablespaces?

• A. When a global temporary table instantiation is too large to fit in memory, space is allocated in a temporary tablespace.
• B. Temporary tablespaces setting Includes quotas to limit temporary space used by a session for that Temporary tablespace.
• C. Lack of temporary tablespace space for sort operations can be prevented by using temporary tablespace groups.
• 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.

正解：A、C

解説：
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

質問 # 42
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