1z0-084 Exam Dumps - Oracle Database 19c: Performance Management and Tuning

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

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

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

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

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