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NEW QUESTION # 10
18. The application provider has given full indications regarding the procedure to collect statistics.
To reduce the space used in the SYSAUX tablespace, you want to prevent the optimizer statistics Advisor from running.
Which method will allow you to do this?
- A. Set the AUTO_STATS_ADVISOR_TASK global statistics preference to FALSE.
- B. Use DBMS STATS.DROP ADVISOR TASK to drop the AUTO_STATS_ADVISOR_TASK task.
- C. Use DBMS_AUTO_TASK_ADMIN. DISABLE to disable the AUTO_STATS_ADVISOR_TASK task.
- D. Set the parameter OPTIMIZER_ADAPTIVE_STATISTICS to FALSE.
Answer: C
Explanation:
The Oracle Optimizer statistics advisor, which is part of the automated tasks framework, can be disabled using the DBMS_AUTO_TASK_ADMIN package. This will prevent it fromrunning and thus reduce space usage in the SYSAUX tablespace.References:
* Oracle Database PL/SQL Packages and Types Reference, 19c
NEW QUESTION # 11
Which two actions can cause invalidation or loss of one or more results in the SQL Query Result Cache?
- A. One or more results were aged out of the result cache.
- B. A request was made by the RCBG background of a non-RAC database.
- C. A request was made by the RCBG background process in a physical standby database that is opened read only and whose primary has a result cache.
- D. result_cache_max_size is set dynamically to 0.
- E. Decreasing the value set for RESULT_CACHE_REMOTE_EXPIRATION.
Answer: A,D
Explanation:
The SQL Query Result Cache stores the results of queries and PL/SQL function calls for reuse. However, entries in the result cache can be invalidated or lost under certain conditions:
A: Results can be aged out of the cache when the cache becomes full and new results need to be stored. This process ensures that the cache does not exceed its allocated memory and that it contains the most recently used entries.
B: Setting theRESULT_CACHE_MAX_SIZEparameter to 0 will effectively disable the result cache and all cached results will be lost, as Oracle will no longer allocate any memory to the result cache.
References:
* Oracle Database Performance Tuning Guide, 19c
NEW QUESTION # 12
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 SESSION CACHED CURSORS = 500;
- B. ALTER SYSTEM SET CURSOR_SHARING = FORCE;
- C. ALTER SYSTEM SET CURSOR_SPACE_FOR_TIME - TRUE;
- D. ALTER SYSTEM SET CURSOR_INVALIDATION = DEFERRED;
Answer: D
Explanation:
Thecursor: pin S wait on Xwait 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 thecursor: pin S wait on Xwait events.
The other options are incorrect in addressing this issue:
* A (Incorrect):SettingCURSOR_SHARINGtoFORCEmakes the optimizer replace literal values with bind variables. It doesn't address the contention for cursor pins directly.
* B (Incorrect):CURSOR_SPACE_FOR_TIME=TRUEaims 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 Xwaits.
* D (Incorrect):IncreasingSESSION_CACHED_CURSORScaches more session cursors but doesn't necessarily prevent the contention indicated by thecursor: pin S wait on Xwait events.
References:
* Oracle Database Reference:CURSOR_INVALIDATION
* Oracle Database Performance Tuning Guide:Reducing Cursor Invalidation
NEW QUESTION # 13
Examine these statements and output:
What parameter change activates the generation and use of SQL Plan Directives7
- A. optimizer_features_enable=12.2.0.1
- B. optimizer_dynamic_sampling=11
- C. optimizer_adaptive_statistics = TRUE
- D. optimizer_capture_sql_plan_baselines_TRUE
- E. optimizer_adaptive_plans=TRUE
Answer: C
Explanation:
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
NEW QUESTION # 14
A database supporting a mixed workload is hosted on a server with 64 CPUs.
A large number of free buffer waits and buffer busy waits occur affecting performance.
The buffer cache size was then increased but after a few hours, the same wait events occur more often than before the change.
Examine these parameter settings:
Which two actions can help reduce the number of these waits7
- A. increasing the value of DBWRITERPROCESSES to 64,
- B. setting dbwr_io_slaves to 64
- C. increasing the value of DB_FILE_MULTIBLOCK_READ_COUNT to 128
- D. reducing the values of DB_FILE_MULTILOCK_READ_COUNT to 64
- E. Increasing the size of MEMORYTARGET
Answer: A,B
Explanation:
Given a server with 64 CPUs, if the buffer cache size increase did not alleviate free buffer waits and buffer busy waits, one can look into optimizing I/O and the efficiency of the DB writer processes.
C: Setting theDBWR_IO_SLAVESparameter to a non-zero value, such as the number of CPUs, would initiate I/O slave processes to assist the DB writer process. This can help reduce I/O contention when writing from the buffer cache to disk, particularly for systems without asynchronous I/O capabilities.
D: Increasing the value ofDBWRITERPROCESSESenables multiple DB writer processes to be active simultaneously. In a system with many CPUs, such as 64, increasing this value can improve the write throughput to disk and potentially reduce buffer busy waits.
References:
* Oracle Database Reference, 19c
* Oracle Database Performance Tuning Guide, 19c
NEW QUESTION # 15
Which two types of performance problems are reported by ADDM for PDBS?
- A. SGA sizing issues
- B. I/O capacity limits
- C. User I/O waits
- D. Excessive checkpoint writes
- E. Top SQL statements
Answer: B,C
Explanation:
The Automatic Database Diagnostic Monitor (ADDM) analyzes and reports on various types of performance problems. For Pluggable Databases (PDBs), it can identify issues such as I/O capacity limits which may hinder the overall performance by causing bottlenecks. Additionally, ADDM can report on user I/O waits, which can indicate performance issues related to the time it takes for user queries to read data from the disk.
References:
* Oracle Multitenant Administrator's Guide, 19c
* Oracle Database Performance Tuning Guide, 19c
NEW QUESTION # 16
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. Lack of temporary tablespace space for sort operations can be prevented by using temporary tablespace groups.
- 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. 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. Temporary tablespaces setting Includes quotas to limit temporary space used by a session for that Temporary tablespace.
Answer: A,B
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 # 17
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: B
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 # 18
You need to collect and aggregate statistics for the ACCTG service and PAYROLL module, and execute:
Where do you find the output of this command?
- A. By viewing V$SERVICE_STATS
- B. In the current working directory
- C. By viewing V$SERV_MOD_ACT_STATS
- D. In $ORACLE_BASE/diag/rdbms/<db unique name>/<instance name>/trace
Answer: C
Explanation:
When you enable statistics gathering for a specific service and module using DBMS_MONITOR.SERV_MOD_ACT_STAT_ENABLE, the output is aggregated and can be viewed using theV$SERV_MOD_ACT_STATSdynamic performance view. This view contains the cumulative statistics of database activity broken down by service and module, which is exactly what you collect when executing the provided command.
* B (Incorrect):While many types of trace files are located in the Diagnostic Destination directory (
$ORACLE_BASE/diag), the aggregated statistics for services and modules are not written to trace files but are instead viewable through dynamic performance views.
* C (Incorrect):TheV$SERVICE_STATSview provides service-level statistics but does not provide the
* combined service/module-level breakdown.
* D (Incorrect):The output of the PL/SQL block is not written to a file in the current working directory; it is stored in the data dictionary and accessible via dynamic performance views.
References:
* Oracle Database PL/SQL Packages and Types Reference:DBMS_MONITOR
* Oracle Database Reference:V$SERV_MOD_ACT_STATS
NEW QUESTION # 19
You need to transport performance data from a Standard Edition to an Enterprise Edition database. What is the recommended method to do this?
- A. Export the data by using the exp utility and parameter file spuexp.par from the Statspack repository and import it by using imp into a dedicated Statspack schema on the destination.
- B. Export the data by using the expdp utility and parameter file spuexp.par from the Statspack repository and import it by using impdp into Export the data by using expdp from the Statspack repository and import it by using impdp into the AWR repository.
- C. Export the data by using expdp from the ftatspack repository and import it by using impdp into the AWR repository.
- D. Export the data by using expdp from Statspack and import it by using
$ORACLE_HOME/rdbms/admin/awrload into the AWRrepository.
Answer: A
Explanation:
To transport performance data from an Oracle Database Standard Edition, which uses Statspack, to an Enterprise Edition database, which uses AWR, you must consider the compatibility of data structures and repository schemas between these tools. The recommended method is:
* D (Correct):Export the data using theexputility with a parameter file appropriate for Statspack (like spuexp.par) from the Statspack repository and import it into a dedicated Statspack schema on the destination. Since Statspack and AWR use different schemas, it's not recommended to import Statspack data directly into the AWR repository.
The other options are incorrect because:
* A (Incorrect):expdpis not designed to export from Statspack, andawrloadis intended for loading from an AWR export file, not a Statspack export.
* B (Incorrect):Althoughexpdpandimpdpare used for exporting and importing data, the AWR repository schema is different from the Statspack schema, so importing Statspack data directly into the AWR repository is not recommended.
* C (Incorrect):Usingexpdpto export from Statspack and then importing directly into the AWR repository is not the correct approach due to the schema differences between Statspack and AWR.
References:
* Oracle Database Performance Tuning Guide:Migrating from Statspack to AWR
NEW QUESTION # 20
Examine this output of a query of VSPGA_TAPGET_ADVICE:
Which statements is true'
- A. PGAA_AGGREGATE should be set to at least 800 MB.
- B. With a target of 700 MB or more, all multipass executions work areas would be eliminated.
- C. GGREGATE_TARGET should be set to at least 700 MB.
- D. With a target of 800 MB or more, all one-pass execution work areas would be eliminated.
Answer: B
Explanation:
The V$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 # 21
This error occurred more than four hours ago in the database:
ORA-04036 PGA memory used by theinstance exceedsPGA_AGGREGATE_LIMIT
You want to know which process and query were at fault.
Which two views should you use for this purpose?
- A. DBA_HIST_SQLTEXT
- B. DBA_HIST_PROCESS_MEM_SUMMARY
- C. DBA_HIST_ACTIVE_SESS_HISTORY
- D. DBA_HIST_SQLSTAT
- E. DBA_HIST_PGASTAT
Answer: B,C
Explanation:
To investigate the cause of the ORA-04036 error, which indicates that PGA memory usage exceeds the PGA_AGGREGATE_LIMIT, the appropriate views to consult are DBA_HIST_ACTIVE_SESS_HISTORYandDBA_HIST_PROCESS_MEM_SUMMARY.
* DBA_HIST_ACTIVE_SESS_HISTORY:This view provides historical information about active sessions in the database. It includes details about the SQL executed, the execution context, and the resources consumed by each session. By examining this view, you can identify the specific sessions and SQL queries that were active and potentially consuming excessive PGA memory around the time the ORA-04036 error occurred.
* DBA_HIST_PROCESS_MEM_SUMMARY:This view contains historical summaries of memory usage by processes. It can help in identifying the processes that were consuming a significant amount of PGA memory, leading to the ORA-04036 error. This view provides aggregated memory usage information over time,making it easier to pinpoint the processes responsible for high PGA memory consumption.
Together, these views offer a comprehensive overview of the memory usage patterns and specific queries or processes that might have contributed to exceeding thePGA_AGGREGATE_LIMIT, resulting in the ORA-04036 error.
References:
* Oracle Database Reference:DBA_HIST_ACTIVE_SESS_HISTORY
* Oracle Database Reference:DBA_HIST_PROCESS_MEM_SUMMARY
* Oracle Database Performance Tuning Guide:Managing Memory
NEW QUESTION # 22
You execute the following:
EXECUTE DBMS_AuTO_TASK_ADMIN.DISABLE;
Which advisor remains enabled?
- A. Automatic Segment Advisor
- B. Automatic SQL Tuning
- C. Automatic Optimizer Statistics Collection
- D. SQL Plan Management Evolve Advisor
- E. Optimizer Statistics Advisor
Answer: C
Explanation:
When you executeDBMS_AUTO_TASK_ADMIN.DISABLE, it disables all automated maintenance tasks related to the Auto Task framework. This includes tasks such as the Automatic SQL Tuning Advisor, Automatic Segment Advisor, and others. However, the Automatic Optimizer Statistics Collection (D) remains enabled as it is not part of the Auto Task framework. The gathering of optimizer statistics is controlled separately and is a critical part of the database's self-tuning mechanism to ensure the optimizer has up-to-date information about the data distribution within tables and indexes.
References
* Oracle Database 19c PL/SQL Packages and Types Reference - DBMS_AUTO_TASK_ADMIN
* Oracle Database 19c Database Administrator's Guide - Managing Optimizer Statistics
NEW QUESTION # 23
You must produce a consolidated formatted trace file by combining all trace files generated by all clients for a single service.
Which combination of utilities does this?
- A. Trcsess and TKPROF
- B. Autotrace and TKPROF
- C. TKPROF and Trace Analyzer
- D. Trace Analyzer and Tracsess
Answer: A
Explanation:
To produce a consolidated formatted trace file from multiple trace files generated by all clients for a single service, the combination oftrcsessandTKPROFutilities is used. Thetrcsessutility consolidates trace files based on specified criteria such as session, client identifier, or service name. This results in a single trace file that combines the desired tracing information. Next,TKPROFis used to format the output of the trace file generated bytrcsess, providing a readable summary of the trace, including execution counts, execution times, and SQL statement text along with execution plans.
Steps:
* Usetrcsessto combine trace files:
* Command:trcsess output=consolidated.trc service=your_service_name *.trc
* UseTKPROFto format the consolidated trace file:
* Command:tkprof consolidated.trc output.txt explain=user/password sys=no sort=prsela,fchela References:
* Oracle Database Performance Tuning Guide, 19c
* Oracle Database Utilities, 19c
NEW QUESTION # 24
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. Partition the SALES table.
- C. Compress the SALES table.
- D. Increase PCTFREE for the SALES table.
- E. Coalesce all sales table indexes.
Answer: B,C
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 # 25
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_POLICYAUTO
- B. Increasing DB_BIG_TABLE_CACHE_PERCENT_TARGET to at least 25
- C. Setting PARALLEL_DEGREE_POLICYADAPTIVE
- D. Increasing DB_CACHESIZE to 1 G
- E. Setting DB_KEEP_CACHE_SIZE to at least 50M
- 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 # 26
Which two options are part of a Soft Parse operation?
- A. Semantic Check
- B. SQL Optimization
- C. Syntax Check
- D. Shared Pool Memory Allocation
- E. SQL Row Source Generation
Answer: A
NEW QUESTION # 27
Which two statements are true about Data Pump import for objects that used the in Memory (IM) column store in their source database?
- A. It always gives preference to the IM column store clause defined at the tablespace level over table-level definitions.
- B. It ignores the IM column store clause of the exporting objects.
- C. Its INMEM0RY_CLAUSE of the Data Pump Export allows modifications to IM column store clause of a table with existing INMEMORY setting.
- D. It must always transports existing INMEMORY attributes.
- E. Its TRANSFORM clause can be used to add the INMEMORV clause to exported tables that lack them.
- F. It can generates the INMEMORY clause that matches the table settings at export time.
Answer: E,F
Explanation:
When importing objects that used the In-Memory (IM) column store in their source database using Oracle Data Pump, the following statements are true:
* D (Correct):TheTRANSFORMclause can be used to alter object creation DDL during import operations. This can include adding theINMEMORYclause to tables that were not originally using the IM column store.
* F (Correct):The import operation can preserve theINMEMORYattributes of tables as they were at the time of export, effectively replicating the IM column store settings from the source database.
The other statements are not accurate in the context of Data Pump import:
* A (Incorrect):Data Pump does not give preference to the IM column store clauses at the tablespace level over table-level definitions unless explicitly specified by theTRANSFORMclause.
* B (Incorrect):While Data Pump can transport existingINMEMORYattributes, it is not mandatory. It is controlled by theINCLUDEorEXCLUDEData Pump parameters or theTRANSFORMclause.
* C (Incorrect):TheINMEMORY_CLAUSEparameter is not part of the Data Pump Export utility. To modify the IM column store clauses, you would use theTRANSFORMparameter during import, not export.
* E (Incorrect):Data Pump does not ignore the IM column store clause unless specifically instructed to do so via theEXCLUDEparameter.
References:
* Oracle Database Utilities:Data Pump Export
* Oracle Database Utilities:Data Pump Import
NEW QUESTION # 28
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. ASH report
- B. Session trace file SQL trace file automatically generated by the error
- C. SQL trace file automatically generated by the error
- D. Alert log
Answer: D
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 # 29
Which two options are part of a Soft Parse operation?
- A. Semantic Check
- B. SQL Optimization
- C. Syntax Check
- D. Shared Pool Memory Allocation
- E. SQL Row Source Generation
Answer: A
Explanation:
During a soft parse, Oracle checks the shared SQL area to see if an incoming SQL statement matches one already in the shared pool. This operation includes syntax and semantic checks. The syntax check ensures the statement is properly formed, and the semantic check confirms that all the objects referenced in the SQL statement exist and that the user has the necessary privileges to access them.References:
* Oracle Database Concepts, 19c
* Oracle Database SQL Tuning Guide, 19c
NEW QUESTION # 30
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. db file scattered read
- B. index range scan
- C. index full scan
- D. db file sequential read
Answer: D
Explanation:
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
NEW QUESTION # 31
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. Partition index IX_SALES_TIME_ID using hash partitioning.
- B. Re-create the SALES table using the columns in IX_SALES_TIME_ID as the hash partitioning key.
- C. Re-create the SALES table sorted in order of index IX_SALES_TIME_ID.
- D. Re-create index IX_SALES_TIME_ID using ADVANCED COMPRESSION.
Answer: D
Explanation:
Given that index range scan operations onIX_SALES_TIME_IDare slower due to an increase in buffer gets, the aim is to improve the efficiency of the index access. In this scenario:
* B (Correct):Re-creating the index usingADVANCED COMPRESSIONcan reduce the size of the index, which can lead to fewer physical reads (reduced I/O) and buffer gets when the index is accessed, as more of the index can fit into memory.
The other options would not be appropriate because:
* A (Incorrect):Re-creating theSALEStable sorted in order of the index might not address the issue of excessive buffer gets. Sorting the table would not improve the efficiency of the index itself.
* C (Incorrect):Using the columns inIX_SALES_TIME_IDas a hash partitioning key for theSALES table is more relevant to data distribution and does not necessarily improve index scan performance.
* D (Incorrect):Hash partitioning the index is generally used to improve the scan performance in a parallel query environment, but it may not reduce the number of buffer gets in a single-threaded query environment.
References:
* Oracle Database SQL Tuning Guide:Managing Indexes
* Oracle Database SQL Tuning Guide:Index Compression
NEW QUESTION # 32
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