1z0-076 Oracle Database 19c: Data Guard Administration Questions and Answers

To increase the number of applier processes on a logical standby database, the following changes can be made:

C: Increasing the value for theMAX_SERVERSSQL apply parameter would allow for more applier processes to be initiated, assuming that system resources permit.

D: Increasing thePARALLEL_MAX_SERVERSinitialization parameter would allow for more parallel execution processes, which can be used by SQL apply to increase the number of applier processes.

Option A is incorrect as decreasing the number of archiver processes will not necessarily increase the number of applier processes; these are unrelated components.

Option B is incorrect because the 'FREPARER' processes do not exist, it seems to be a typographical error, and the 'REPARER' is not a valid Oracle process or parameter.

Option E is incorrect because theRECOVERY_PARALLELISMparameter controls the number of processes used for instance recovery and media recovery, not for SQL apply.

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

ThefastStartFailoverTargetproperty is not set onDogs(A):The primary database (Dogs) needs to have a fast-start failover target configured for the operation to succeed.

TheLogXptModeproperty is set toASYNConSheepwhileSheepis the target standby database (B):Fast-start failover requires synchronous redo transport (SYNCorFASTSYNC) to ensure zero data loss, which is a prerequisite for enabling the feature.

Oracle Multi-tenant architecture and Data Guard have several interactions, but specific aspects hold true in such environments:

The Data Guard broker may be used for multi-tenant databases (B):Data Guard Broker simplifies the management and monitoring of Data Guard configurations and is fully compatible with the Oracle Multi-tenant architecture, allowing for easy management of Data Guard configurations that include multi-tenant container databases (CDBs) and their pluggable databases (PDBs).

The commandALTER DATABASE FLASHBACK ON;enables the Flashback Database feature, which provides a way to quickly revert an entire Oracle database back to a previous point in time. This command can be executed while an Oracle 19c primary database is either open (option A) or mounted (option B). It is also applicable to an Oracle 19c logical standby database while SQL Apply is active (option E). However, it's important to note that enabling Flashback Database on the primary does not automatically enable it on all associated standby databases, whether they are physical or logical. Each database in a Data Guard configuration must have Flashback Database explicitly enabled if desired. Real Time Query being active on a physical standby does not directly relate to the ability to execute this command on the standby.References:The explanation is based on Oracle's concepts for Flashback Technology and Data Guard configurations as detailed in the Oracle Database Backup and Recovery User's Guide and the Oracle Data Guard Concepts and Administration guide.

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.

Enterprise Manager Cloud Control provides a graphical interface to manage multiple standby databases, simplify switchovers and failovers, and automate failover processes to a specified target standby database. It offers a comprehensive view and control over the Data Guard configuration, making complex operations more manageable.

DGMGRL is a command-line tool specifically designed for managing Data Guard configurations. It allows the administration of multiple standby databases, simplifies the execution of switchovers and failovers, reinstatements, and conversions to and from snapshot standby databases, and supports the automation of failover processes to a specified standby database.

Other options like RMAN, SQL*Plus, CRSCTL, SRVCTL, and GDCCTL do not provide the same level of integrated management functionality for Data Guard environments as Enterprise Manager Cloud Control and DGMGRL.

The command executed (CREATE CONFIGURATION 'DGConfig' AS PRIMARY DATABASE IS 'PROD' CONNECT IDENTIFIER IS PROD;) is used to create a Data Guard Broker configuration named 'DGConfig'. The successful execution of this command depends on several conditions:

A: TheDG_BROKER_STARTparameter must be set toTRUEon the primary database to start the Data Guard Broker processes. Without the broker processes running, the configuration cannot be created.

D: Oracle Net connectivity to the PROD database instance must be established on the primary host. This is because the Data Guard Broker requires network accessibility to communicate with the primary database and manage the configuration.

E: When the configuration is created, the Data Guard Broker configuration files are indeed automatically created in the locations specified by theDG_BROKER_CONFIG_FILEnparameters on the primary database.

It's important to note that the command will not automatically add the PRODSBY1 standby database to the configuration (thus B and C are not correct), and there is no requirement for the standby database to have Oracle Net connectivity defined on the primary host for the execution of this command (making F incorrect as well).

In the context of Oracle Data Guard and container databases (CDBs) managed by Data Guard Broker:

All broker actions execute at the root container for container databases (D):When using Data Guard Broker to manage a CDB, the actions performed by the broker are executed at the level of the root container. This is because the root container maintains the control and configuration information that applies to the entire CDB, including all of its pluggable databases (PDBs).

For seamless client redirection in a Data Guard environment, the following steps should be taken:

Create a database service on the primary database that is started automatically by a trigger when the database role is PRIMARY (B):This ensures that the service is only available on the primary database and is automatically started after a role transition due to switchover or failover.

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.

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.

In Oracle, a sequence created with theGLOBALkeyword is available and can produce values across all sessions and instances. However, a sequence created with theSESSIONkeyword is only specific to the session it was created in. When theNEXTVALis called for a sequence, it will increment according to the sequence's properties set during its creation.

Given the sequence creation statements and the actions performed:

Theasequence is global, which means it is available across the entire database, including the standby database with Real-Time Query enabled. So, when session 2 callsa.nextval, it will get the next value in the sequence, which is 21 since session 1 already retrieved 1.

Thebsequence is session-specific, so when session 2 callsb.nextval, it will get the value 1 because for this new session on the standby, this is the first time the sequence is being accessed.

Therefore, the output for session 2 will beaoutput as 21 andboutput as 1, which corresponds to Option C.

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 <location of the PDB> in the london database (C):This parameter specifies the location on the standby database where the files from the source PDB should be placed.

Based on the Oracle Database 19c documentation, the correct answers about SQL Apply filters for a logical standby database are:

A. They can be used to skip execution of DML triggers on a table while allowing the DML to execute.

B. They can be used to skip CREATE TABLE commands.

C. They can be used to skip ALTER SYSTEM and ALTER DATABASE commands.

G. They can be used to skip ALTER TABLE commands on specific tables.

Comprehensive Detailed Explanation:

SQL Apply filters in a logical standby database can be set to control which SQL operations are applied to the standby. These filters allow for certain commands to be skipped, ensuring that they do not impact the standby database. For example, filters can be used to skip the execution of DML triggers to prevent them from firing during SQL Apply, while still allowing the underlying DML to be executed on the logical standby database. This is particularly useful when certain triggers are not desired to run in a standby environment. CREATE TABLE, ALTER SYSTEM, ALTER DATABASE, and specific ALTER TABLE commands can also be skipped using SQL Apply filters to prevent unwanted structural changes or administrative operations from affecting the logical standby database. These capabilities provide a level of control to ensure that the logical standby database reflects only the desired state of the primary database.

To meet the requirements of automatic failover and the highest level of protection without data loss, the combination of FASTSYNC redo transport mode and Maximum Availability protection mode is appropriate. FASTSYNC ensures that the performance impact on the primary database is minimized while still providing synchronous transport. Maximum Availability protection mode offers the highest level of data protection without compromising the availability of the primary database. In case of a network failure or a standby failure, the primary will not halt, avoiding disruption to the primary database operations.

References

Oracle Data Guard Concepts and Administration guide, which details the different protection modes and their respective levels of data protection and impact on database operations.

In a Data Guard environment, offloading backups to a physical standby database has certain requirements:

A: Once the primary database is registered in an RMAN catalog, the standby database can also be registered. This allows RMAN to manage backups coherently across both databases and leverage the standby database for backup purposes without interfering with the primary database's workload.

C: Backups of the standby control file taken while connected to the catalog where the database is registered can be used to restore the control file on the primary database. This ensures that backup metadata is consistent across the Data Guard configuration.

Options B and D are incorrect because there is no strict requirement for the order in which the primary and standby databases must be registered in an RMAN catalog. However, it is a common practice to register the primary database first.

Automatic Block Media Recovery can be a significant feature for maintaining data integrity within a Data Guard configuration.

A corrupt block on the primary database can be automatically recovered, using a block from a standby database with Real-Time Query enabled (A):When a corrupted block is encountered on the primary database, Oracle can automatically replace it with a good block from the standby database where Real-Time Query is enabled, leveraging the standby as a source of good data.

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.