2024年最新のの問題Oracle Database 19cと1z1-084リアル試験問をマスターせよ！
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質問 # 10
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$SESSION_LONGOPS
- B. V$SESSION
- C. V$SESSTAT
- D. V$RMAN_BACKUP_JOB_DETAILS
正解：A
解説：
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
質問 # 11
Examine these commands, which execute successfully:
Which statement is true?
- A. AWR- snapshots in all pluggable databases will be purgedautomatically 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：
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
質問 # 12
Which three types of statistics are captured by statspack with snap level 6?
- A. Segment-level statistics
- B. Parent and child latches
- C. Optimizer execution plans
- D. Plan usage data
- E. Parent and child latches
- F. Enqueue statistics
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 # 13
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 critical alert will be issued when CPU time exceeds 10000 microseconds for each user call.
- B. A critical alert will be issued when CPU time exceeds 2 minutes for each user call.
- C. A warning alert will be issued only when CPU time exceeds 10000 microseconds for each user call.
- D. A warning alert will be issued when CPU time exceeds 1 minute for each user call.
正解：A
解説：
In the provided code block, theDBMS_SERVER_ALERT.SET_THRESHOLDprocedure 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 theSET_THRESHOLDprocedure are as follows:
* The first parameterDBMS_SERVER_ALERT.CPU_TIME_PER_CALLspecifies the metric for which the threshold is being set, in this case, the CPU time consumed per database call.
* The second and third parametersDBMS_SERVER_ALERT.OPERATOR_GEand'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 parametersDBMS_SERVER_ALERT.OPERATOR_GEand'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 theDBMS_SERVER_ALERT.SET_THRESHOLDprocedure, 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.
質問 # 14
Examine these statements and output:
What parameter change activates the generation and use of SQL Plan Directives7
- A. optimizer_adaptive_statistics = TRUE
- B. optimizer_features_enable=12.2.0.1
- C. optimizer_dynamic_sampling=11
- D. optimizer_capture_sql_plan_baselines_TRUE
- E. optimizer_adaptive_plans=TRUE
正解：A
解説：
The optimizer_adaptive_statistics parameter, when set to TRUE, enables the optimizer to use adaptive statistics, such as SQL Plan Directives, to help improve plans by automatically adjusting them based on the actual execution statistics.
References:
* Oracle Database SQL Tuning Guide, 19c
質問 # 15
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. Re-create the SALES table.
- B. Coalesce all sales table indexes.
- C. Increase PCTFREE for the SALES table.
- D. Partition the SALES table.
- E. Compress the SALES table.
正解：D、E
解説：
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.
質問 # 16
Which two options are part of a Soft Parse operation?
- A. Syntax Check
- B. SQL Row Source Generation
- C. Shared Pool Memory Allocation
- D. Semantic Check
- E. SQL Optimization
正解：D
解説：
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
質問 # 17
Which three statements are true about server-generated alerts?
- A. They provide notifications but never any suggestions for correcting the identified problems.
- B. They may contain suggestions for correcting the identified problems.
- C. They are logged in the alert log.
- D. They are notifications from the Oracle Database Server of an existing or impending problem.
- E. They can be viewed only from the Cloud Control Database home page.
- F. Their threshold settings can be modified by using DBMS_SERVER_ALERT.
正解：B、C、D
解説：
Server-generated alerts in Oracle Database are designed to notify DBAs and other administrators about issues within the database environment. These alerts can be triggered by a variety of conditions, including threshold-based metrics and specific events such as ORA- error messages. Here's how these options align with the statements provided:
* A (True):Server-generated alerts are indeed notifications from the Oracle Database Server that highlight existing or impending issues. These alerts are part of Oracle's proactive management capabilities, designed to inform administrators about potential problems before they escalate.
* C (True):These alerts are logged in the alert log of the Oracle Database. The alert log is a crucial diagnostic tool that records major events and changes in the database, including server-generated alerts.
This log is often the first place DBAs look when troubleshooting database issues.
* F (True):Server-generated alerts may include suggestions for correcting identified problems. Oracle Database often provides actionable advice within these alerts to assist in resolving issues more efficiently. These suggestions can range from adjusting configuration parameters to performing specific maintenance tasks.
Options B, D, and E do not accurately describe server-generated alerts:
* B (False):While the statement might have been true in some contexts, Oracle's server-generated alerts often include corrective suggestions, making this statement incorrect.
* D (False):Server-generated alerts can be viewed from various interfaces, not just the Cloud Control Database home page. They are accessible through Enterprise Manager, SQL Developer, and directly within the database alert log, among other tools.
* E (False):While it's true that threshold settings for some alerts can be modified, the method specified, usingDBMS_SERVER_ALERT, is not correct. Threshold settings are typically adjusted through Enterprise Manager or by modifying specific initialization parameters directly.
References:
* Oracle Database Documentation:Oracle Database 19c: Performance Management and Tuning
* Oracle Base: Alert Log and Trace Files
* Oracle Support:Understanding and Managing Server-Generated Alerts
質問 # 18
Buffer cache access is too frequent when querying the SALES table. Examine this command which executes successfully:
ALTER TABLE SALES SHRINK SPACE;
For which access method does query performance on sales improve?
- A. index range scan
- B. db file sequential read
- C. index full scan
- D. db file scattered read
正解：B
解説：
The SHRINK SPACE operation compacts the table, which can reduce fragmentation and thus improve performance for sequential reads of the table. This operation could improve full table scans, which are typically associated with db file sequential read wait events.
References:
* Oracle Database Administrator's Guide, 19c
質問 # 19
Which two statements are true about session wait information contained in v$session or v$session_wait?
- A. Rows for sessions that are not waiting always contain the total wait time since the session started.
- B. Rows for sessions that are currently waiting have a wait time of 0.
- C. Rows for sessions displaying WAITED UNKNOWN TIME in the STATE column indicate that the session is still waiting.
- D. Rows for sessions that are currently waiting have their wait time incremented every microsecond.
- E. Rows for sessions that are not waiting might contain the actual wait time for the last event for which they waited.
正解：B、E
解説：
In theV$SESSIONview, Oracle provides information about the session waits:
B: When theWAIT_TIMEcolumn has a value of 0, it signifies that the session is currently waiting for a resource. This column represents the duration of the current or last wait.
C: If the session is not actively waiting, theWAIT_TIMEcolumn shows the time the session spent waiting for the last wait event. If theSTATEcolumn is showing "WAITED KNOWN TIME", it means the session is not currently waiting, but it indicates the time for which it had waited.
References:
* Oracle Database Reference, 19c
* Oracle Database Performance Tuning Guide, 19c
質問 # 20
You use SQL Tuning Advisor to tune a given SQL statement.
The analysis eventually results in the implementation of a SQL Profile.
You then generate the new SQL Profile plan and enforce it using a SQL PlanBaselinebut forget to disable the SQLProfile and a few days later you find out that the SQL Profile is generating a new execution plan.
Which two statements are true?
- A. The execution plan is the one enforced by the SQL Plan Baseline.
- B. The SQL Plan Baseline must be accepted in order to be used for the execution plan.
- C. The SQL Profiles as well as SQL Plan Baseline are implemented using hints, so they both generate the same plan.
- D. The existence of two concurrent plan stability methods generates a child cursor for every execution.
- E. The execution plan is the one enforced by the SQL Profile.
- F. The conflict between the two plan stability methods results in an error.
正解：B、E
解説：
When both a SQL Profile and a SQL Plan Baseline are in place, the SQL Profile has a stronger preference and the optimizer is more likely to choose the execution plan from the SQL Profile.
C: A SQL Profile is generally more influential than a SQL Plan Baseline because it contains additional statistics and directives that help the optimizer to generate a more efficient execution plan. If both exist, the optimizer will use the profile's plan unless the baseline's plan is proven to be better through the SQL performance monitoring process.
E: SQL Plan Baselines must be accepted before they can be used by the optimizer. If a SQL Plan Baseline is not accepted, it will not be considered for generating the execution plan. Therefore, the presence of an unaccepted SQL Plan Baseline will not automatically force the optimizer to use its plan.
References:
* Oracle Database SQL Tuning Guide, 19c
* Oracle Database Administrator's Guide, 19c
質問 # 21
Which application lifecycle phase could be managed reactively?
- A. Testing
- B. Deployment
- C. Production
- D. Design and development
- E. Upgrade or migration
正解：C
解説：
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
質問 # 22
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
正解：C
解説：
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
質問 # 23
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 rewriting the SQL statements
- B. recommendations regarding the creation of SQL Patches
- C. recommendations regarding the creation of additional indexes
- D. recommendations regarding the creation of materialized views
- E. recommendations regarding partitioning the tables
正解：C、D
解説：
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
質問 # 24
Multiple sessions are inserting data concurrently into a table that has an LOB column.
At some point in time, one of the sessions cannot find available space in the LOB segment and needs to allocate a new extent.
Which wait event will be raised in the other sessions that need space in the LOB column?
- A. enq: SQ - contention
- B. enq: TX - allocate ITL entry
- C. enq: TM - contention
- D. enq: HW - contention
正解：D
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 # 25
Which two statements are true about cursor sharing?
- A. Setting optimizer_capture_sql_plan_baselines to TRUE loads all adaptive plans for the same statement into the cursor cache.
- B. Setting cursor_sharing to EXACT prevents Adaptive Cursor Sharing from being used.
- C. Adaptive Cursor Sharing requires histograms on filtered columns, used in equality predicates, to allow different execution plans to be generated for statements whose bound values would normally generate different plans at hard parse time.
- D. Setting Cursor_sharing to FORCE can result in a plan that is suboptimal for the majority of values bound to a bind variable when executing a cursor with one or more bind variables.
- E. Adaptive Cursor Sharing guarantees that a suboptimal plan will never be used on any execution of a SQL statement.
正解：B、D
解説：
A: WhenCursor_sharingis set toFORCE, Oracle tries to avoid hard parses by replacing literals in SQL statements with bind variables, even if the original statement didn't include bind variables. This can lead to the use of a single execution plan for multiple executions of a statement with different literal values, which might not be optimal for all executions.
D: Settingcursor_sharingtoEXACTensures that SQL statements must match exactly for them to share a cursor. This setting prevents the use of Adaptive Cursor Sharing (ACS) since ACS relies on the ability to share cursors among similar statements that differ only in their literal values. WithEXACT, there's no cursor sharing for statements with different literals, hence no opportunity for ACS to operate.
References:
* Oracle Database SQL Tuning Guide, 19c
* Oracle Database Reference, 19c
質問 # 26
Examine this statement and output:
Which three statements are true?
- A. Session 9857 waited 1354 seconds for another process, which was also waiting for a transaction to end.
- B. Both 9822 and 8779 sessions are waiting for operating system resources.
- C. Session 8779 may be waiting for a user or application response.
- 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. Session 8779 may be waiting due to a network problem.
正解：C、E、F
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 # 27
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