1z0-076 Exam Dumps - Oracle Database 19c: Data Guard Administration

In an Oracle Active Data Guard environment:

• B: Read-mostly reporting applications that utilize global temporary tables to store session-specific data can be effectively offloaded to an Active Data Guard standby database, reducing the load on the primary database.
• C: Sequences can be used with global temporary tables on an Active Data Guard standby database to support certain types of read-mostly applications, though some restrictions on sequence use may apply.
• E: In Oracle Database 19c and later, DML redirection allows DML operations performed on an Active Data Guard standby database to be transparently redirected to the primary database. This is part of the DML Redirection feature.

Option A is incorrect because not all PL/SQL blocks run on an Active Data Guard standby database can be redirected to the primary database. Some PL/SQL executions, specifically those that would attempt to make changes to the database, are not supported on the standby.

Option D is incorrect because DDL operations on private temporary tables are not redirected; instead, private temporary tables are session-specific and are not persisted on disk, so they do not generate redo and are not applicable to an Active Data Guard standby.

References: The behavior and capabilities of Active Data Guard standby databases are documented in the Oracle Data Guard Concepts and Administration guide and the Active Data Guard documentation.

To reduce the redo apply lag on standby databases, one could increase the size of the standby redo log files. Larger redo log files can accommodate more redo data, which may reduce the frequency of log switches and allow for more continuous application of redo data. Additionally, lowering the DB_BLOCK_CHECKING parameter to MEDIUM or LOW on the standby databases can help improve redo apply performance. High block checking can impose additional CPU overhead during the application of redo data, potentially increasing apply lag times. By reducing the level of block checking, you can lessen this overhead and help reduce the apply lag ​​.

• The command performs a comprehensive set of database checks prior to a role change (A): The VALIDATE DATABASE command in Data Guard Manager (DGMGRL) is designed to perform an exhaustive check of a specified database's readiness for a role change, such as a switchover or failover.
• The command performs network connectivity checks between members of a broker configuration (C): One of the checks includes verifying that the necessary network connectivity exists between the databases in a Data Guard Broker configuration.
• The command can be used for a logical standby database (D): The VALIDATE DATABASE command is versatile and can be used for both physical and logical standby databases to ensure their readiness for role changes.

References:

• Oracle Data Guard Broker documentation
• Oracle Data Guard Concepts and Administration Guide

The execution of the UNSKIP procedure is designed to remove SQL Apply filters that have been previously set up on a logical standby database. Based on the provided statements, the UNSKIP procedure is directed to delete any SQL Apply filters for DML statements associated with objects in the 'HR' schema that start with 'EMP'. Since both SKIP procedures had the same schema name ('HR') and statement type ('DML'), and the UNSKIP procedure uses a wildcard (%) for the object name, it will successfully remove both of the SQL Apply filters for 'EMP_NEW' and 'EMP_OLD', as both object names match the pattern provided in the UNSKIP procedure.

References:Oracle's Data Guard documentation and SQL Language Reference provide insights into managing SQL Apply filters on a logical standby database using the DBMS_LOGSTDBY package. This includes adding and removing filters through SKIP and UNSKIP procedures.

To automate the instantiation of a PDB in the standby database after creating a remote clone in the primary database, certain conditions must be met:

• Open PDBI (remote clone source) in Read Only (A): The source PDB from which the clone is created must be open in read-only mode to ensure a consistent state during cloning.
• Set STANDBY_PDB_SOURCE_FILE_DIRECTORY to in the london database (C): This parameter specifies the location on the standby database where the files from the source PDB should be placed.
• Set STANDBY_FILE_MANAGEMENT to auto in the london database (F): This parameter automates the management of file changes on the standby database when structural changes occur on the primary database, ensuring that the clone operation is reflected automatically on the standby.References:
• Oracle Multitenant Administrator's Guide
• Oracle Data Guard Broker documentation

The DBMS_COMPARISON package, used for comparing and converging data objects within a single database or between databases, requires that the databases involved in the block comparison be at least mounted (A). This allows the procedure to access the data blocks for comparison. Additionally, the progress of long-running operations such as block comparison can be monitored using the dynamic performance view V$SESSION_LONGOPS (D), which provides information on the operation's progress and estimated completion time.

References:Oracle Database PL/SQL Packages and Types Reference provides comprehensive details on the DBMS_COMPARISON package, including its procedures and how to monitor their progress. Additionally, Oracle Database Reference explains the V$SESSION_LONGOPS view, which is commonly used for monitoring long operations in the database.

After a successful failover to the 'cats' database in a Data Guard configuration:

• B: Sheep, being another standby database, would typically remain in the enabled state unless specifically disabled or if there was a configuration issue.
• D: Dogs, which was the primary database prior to failover, will be in a disabled state as part of the failover process. Manual intervention is required to re-establish 'dogs' as a standby database or to return it to the primary role through another role transition.
• E: If the configuration was in Maximum Availability mode before failover, it would remain in this mode after failover, provided all settings were properly configured and no changes were made to the protection mode.

Option A is incorrect because failover does not automatically change the protection mode to Maximum Performance. The protection mode remains as it was prior to the failover unless manually altered.

References: The behavior of Oracle Data Guard during failover and the resulting configuration state is described in the Oracle Data Guard Broker documentation.

• DB_NAME (A): The name of the database, which should remain consistent across the primary and standby databases.
• db_file_name_convert (C): This parameter helps define the mapping of data file names from the primary to the standby database, which is crucial during the creation and operation of a standby database.
• COMPATIBLE (D): The compatibility level can influence the features that can be used on the standby database and must be consistent with or higher than that of the primary database, especially after upgrades.
• STANDBY_ARCHIVE_DEST (F): This parameter specifies the destination of archived redo log files on the standby database, which is important for log transport and apply services.

References:

• Oracle Data Guard Concepts and Administration Guide
• Oracle Database Reference

When enabling fast-start failover, certain conditions must be met:

• The fastStartFailoverTarget property is not set on Dogs (A): The primary database (Dogs) needs to have a fast-start failover target configured for the operation to succeed.
• The LogXptMode property is set to ASYNC on Sheep while Sheep is the target standby database (B): Fast-start failover requires synchronous redo transport (SYNC or FASTSYNC) to ensure zero data loss, which is a prerequisite for enabling the feature.
• The LogXptMode property is set to ASYNC on Dogs (D): Similar to the previous point, the primary database must be configured to use synchronous redo transport for the fast-start failover to be possible.References:
• Oracle Data Guard Broker documentation
• Oracle Database Error Messages Guide

The rate of SQL apply on a logical standby database can be influenced by:

• A: The number of PREPARER processes (which seems to be a typographical error and should read as PREPARER or similar) which prepare the redo data for the applier processes.
• B: The number of coordinator processes on the standby database instance which coordinate the SQL apply activities.
• C: The number of full table scans performed by SQL apply since full table scans can be resource-intensive and slow down the apply rate.
• E: The number of applier processes which apply the redo data to the logical standby database.

Option D is incorrect as the size of the undo tablespace on the logical standby database is more likely to affect the SQL apply lag rather than the rate of SQL apply.

Option F is incorrect because the size of the shared pool would typically not influence the rate of SQL apply. The shared pool is more related to the caching of shared SQL and PL/SQL code and control structures.

References: Oracle's documentation on SQL Apply in Data Guard configurations discusses the factors affecting the performance of SQL Apply operations on logical standby databases.

• A static service must be registered with the local listener to enable DGMGRL to restart instances during the course of broker operations (A): For DGMGRL (Data Guard Manager Command-Line Interface) to perform instance management operations, such as restarting instances, a static service registration in the listener is required. This allows the broker to connect to the database instance even when the instance is not fully up and the dynamic service registration is not available.
• Installing the oracle-database-preinstall-19c package is NOT sufficient to set up operating system kernel parameters for Oracle Net (C): While the oracle-database-preinstall-19c package automates the setting of several kernel parameters to meet the preinstallation requirements for Oracle Database, it does not specifically tailor all settings for Oracle Net in a Data Guard configuration. Additional manual configuration may be required to optimize Oracle Net services for Data Guard operations.

References:

• Oracle Data Guard Broker documentation
• Oracle Net Services Administrator's Guide

• Stop the Observer on host1 to ensure that there are no conflicts between the instances of the Observer running on different hosts.
• Update the Data Guard Broker configuration with the new hostname for the Observer. This step is crucial to redirect the Data Guard Broker to communicate with the Observer on the new host.
• Start the Observer on host2 to resume its operations in the new environment.

Disabling and re-enabling Fast-Start Failover (steps 2 and 4) are not strictly necessary for moving the Observer to a new host. These steps would be more relevant if changes to the configuration of Fast-Start Failover itself were required, which is not the case when simply relocating the Observer.

Creating a physical standby database using RMAN active database duplication requires certain prerequisites to ensure a successful and seamless operation:

• Configure Oracle Net connectivity on the primary host to the standby database instance (A): Proper Oracle Net connectivity between the primary and standby servers is essential for communication and data transfer during the duplication process. Oracle Net services provide the network foundation for Oracle Database, Oracle Net Listener, and Oracle applications.
• Establish user equivalence for the database software owner between the primary host and standby host (B): User equivalence ensures that the user who owns the Oracle Database software on the primary server has the same privileges on the standby server. This is crucial for RMAN to perform operations on both servers without encountering permission issues.
• Startup nomount the standby database instance (C): The standby database instance needs to be started in the NOMOUNT stage before the duplication can begin. This prepares the environment for creating the control file and restoring the database without mounting it, which is a necessary step in the RMAN duplication process.References:
• Oracle Database Backup and Recovery User's Guide
• Oracle Data Guard Concepts and Administration

After a successful switchover operation in a Data Guard environment, the new primary database (the former standby) will be open read-write (option A). If the former primary database transitions to a logical standby database, it will also be open read-write (option C), allowing it to apply redo data while servicing read-only queries. The former primary, if converted to a physical standby, will adopt the state that the former physical standby database was in prior to the switchover, which can vary based on the configuration prior to the switchover (option D). The state of a physical standby database can range from mounted to open read-only, depending on whether Real-Time Query was enabled. Thus, the exact state will depend on the pre-switchover setup. It's also essential to highlight that options B and E suggest specific states for a former primary turned logical standby, and a former primary turned physical standby, respectively, but these states are not fixed and depend on the configurations set up by the database administrators. References: The answers are corroborated by Oracle's documentation on Data Guard switchovers, specifically in the Oracle Data Guard Concepts and Administration guide, which explains the roles and states of databases in a Data Guard configuration before and after switchovers.

The ORA-03172: STANDBY_MAX_DATA_DELAY error indicates that the real-time query on the physical standby database is experiencing delays beyond the specified maximum data delay threshold. Increasing the network bandwidth (Option E) can enhance the speed at which redo data is transferred from the primary to the standby database, thereby reducing the likelihood of exceeding the STANDBY_MAX_DATA_DELAY threshold. Reducing I/O latency on the primary database's storage (Option B) ensures that redo data is generated and shipped more efficiently, further mitigating the risk of delay. These actions, focused on optimizing data transfer and processing speed, address the root causes of the ORA-03172 error in a synchronous Data Guard configuration operating in Maximum Availability mode.

When a physical standby database is opened in real-time query mode, which may be referred to as real-time apply when using Active Data Guard, certain operations can disrupt ongoing sessions. However, with features like Application Continuity and the proper configuration of initialization parameters such as STANDBY_DB_PRESERVE_STATES, user sessions and current buffers may be preserved during role transitions such as a switchover or failover. Specifically, the STANDBY_DB_PRESERVE_STATES parameter can be set to preserve none, all, or only user sessions during such transitions. This ensures that in-flight transactions are not lost and that users do not experience disruptions during the role transitions of a physical standby database​​​​.

References

• Oracle Data Guard Concepts and Administration​​
• Oracle Database Licensing Information User Manual​​
• Oracle Data Guard Broker User Manual​

To enable Fast-Start Failover in a Data Guard environment, the following conditions must be in place:

• The Data Guard environment must be managed by the Data Guard Broker (A): The Broker simplifies management tasks and is required to enable fast-start failover, which is an automatic failover mechanism provided by Data Guard.
• You can specify only one standby database as the fast-start failover target (C): Fast-start failover is designed to fail over to a single, predetermined standby database, known as the target standby.
• Flashback Database must be enabled on both the primary database and the Fast-Start Failover target standby database (F): Flashback Database provides a quick way to revert a database to a point in time before a logical or physical corruption or error occurred. It must be enabled on both the primary and target standby databases to allow for the possibility of reinstating the old primary as a standby after a failover.References:
• Oracle Data Guard Concepts and Administration Guide
• Oracle Database High Availability Overview

• Logical standby databases allow the execution of DDL and DML operations, which makes them suitable for maintaining bitmap indexes and materialized views without affecting the performance of the primary database .
• Logical standby databases can be used for performing rolling upgrades and patching with minimum downtime, meeting another requirement .
• They also enable the testing of new application software releases against an up-to-date replica of the primary database, fulfilling the last requirement.

Other configurations involving physical standby databases or combinations of logical and physical standby databases might not meet all the specified requirements as efficiently or with the same level of performance isolation for the primary database.