Data Systems Administration (D330)

Explanation:

The Database Writer (DBWn) process is responsible for writing dirty blocks from the buffer cache to datafiles, but it is not triggered by a commit. Committing a transaction signals LGWR to write the redo log entries, ensuring the commit is durable. DBWn writes blocks to disk based on buffer cache thresholds or checkpoints, independent of individual commits.

Correct Answer:

Does nothing.

Why Other Options Are Wrong:

Writes the changed blocks to data files.

DBWn writes dirty blocks to data files based on its internal schedule or during checkpoints, but a commit by itself does not force DBWn to write data immediately. Assuming that DBWn responds directly to a commit is incorrect.

Writes the changed blocks to redo log files.

Redo log files are written by LGWR, not DBWn. DBWn only manages datafile blocks in memory and has no role in writing redo information, so this option is inaccurate.

Triggers checkpoint and thus LGWR writes the changes to redo log files.

Although checkpoints eventually involve DBWn and CKPT, a single commit does not trigger a checkpoint. LGWR handles redo log writes at commit time, making this explanation unrelated to DBWn’s actual behavior.

Explanation:

The utlu121s.sql script is the official Oracle post-upgrade status tool. After an upgrade, running this script reports the upgrade status of each database component and verifies that all components are at the correct version. It is specifically designed to help administrators confirm that the upgrade process completed successfully and that no component remains invalid or out of date.

Correct Answer:

utlu121s.sql

Why Other Options Are Wrong:

utluiobj.sql

This script checks for invalid objects and provides information about them, but it does not give a complete status report of the entire upgrade process. While it can be helpful for troubleshooting invalid objects, it lacks the comprehensive upgrade verification that utlu121s.sql provides.

emremove.sql

This script is used to remove Enterprise Manager Database Control configuration files. It has nothing to do with validating or reporting the results of a database upgrade, so it cannot provide status upgrade information.

catuppst.sql

This script runs as part of the upgrade process to perform certain post-upgrade actions, but it does not produce the final detailed status report. It is a step within the upgrade procedure rather than a reporting tool for upgrade verification.

Explanation:

The Automatic Diagnostic Repository Command Interface (adrci) is an interactive command-line tool that lets administrators view and manage diagnostic data, including the database alert log. Using adrci, you can display the alert log in real time or query historical diagnostic information without manually opening log files.

Correct Answer:

adrci

Why Other Options Are Wrong:

imp

The imp utility is used to import data from dump files created by the export utility. It does not provide any functionality to view or manage diagnostic files such as the alert log.

lsnrctl

lsnrctl manages and monitors the Oracle Net Listener, allowing you to start, stop, and check the status of listeners. It does not access or present the database alert log contents.

tkprof

tkprof formats and analyzes SQL trace files to evaluate SQL execution plans and performance. It is not used to view the alert log or any diagnostic repository data.

Explanation:

Automatic Memory Management (AMM) and Automatic Shared Memory Management (ASMM) simplify memory allocation for the Oracle database by allowing the database to automatically manage and distribute memory among SGA and PGA components. This eliminates the need for the DBA to manually configure and tune individual memory areas such as the shared pool, buffer cache, or redo log buffer. The system monitors usage and dynamically adjusts allocations to optimize performance, reducing administrative overhead and the risk of misconfiguration.

Correct Answer:

The DBA does not need to tune individual components.

Why Other Options Are Wrong:

The DBA can fine-tune individual components.

While AMM/ASMM simplifies memory management, it is specifically designed to reduce or eliminate manual tuning. Although fine-tuning is still possible in some advanced scenarios, the main advantage of AMM/ASMM is automatic allocation, making this option misleading.

It allows the database to start without a control file.

Memory management features have no impact on the presence of control files. Control files are mandatory for the database to start, so this option is unrelated to the benefits of AMM or ASMM.

It makes the redo log buffer dynamically alterable.

Although the redo log buffer can sometimes be adjusted dynamically, this is not the primary advantage of AMM or ASMM. These features manage all memory components collectively and automatically rather than specifically enabling redo log buffer alterations.

Explanation:

The SERVER=DEDICATED parameter in a tnsnames.ora file specifies that each client connection will use a dedicated server process. In this configuration, the Oracle Listener spawns a new dedicated process for every client session. This is appropriate for sessions that require consistent resources or have heavy workloads, as each client is guaranteed its own server process. Shared, pooled, or dispatched processes are used in different configurations such as shared server mode, but those are not what SERVER=DEDICATED represents.

Correct Answer:

A committed server process

Why Other Options Are Wrong:

A shared server process is used in a shared server architecture where multiple client sessions share a pool of server processes to optimize resource usage. This is the opposite of a dedicated server setup, so it does not correspond to the SERVER=DEDICATED parameter.

A pooled server process refers to a concept used in connection pooling where server resources are shared among a pool of connections for efficiency. While pooling reduces overhead, it is not the mechanism defined by SERVER=DEDICATED, which explicitly ensures one dedicated server process per client session.

A dispatched server process is involved in shared server configurations, where a dispatcher routes client requests to available shared server processes. This method allows many clients to use fewer server processes, contrasting with the one-to-one mapping required by SERVER=DEDICATED.

Explanation:

When accessing a remote object through a database link, Oracle requires the fully qualified form schema.object@dblink. In this case the schema is Scott, the table is employee, and the database link is wgu2021. The correct reference is therefore scott.employee@wgu2021. This tells Oracle to retrieve the employee table owned by Scott on the remote database defined by the wgu2021 link. Without the @wgu2021 qualifier, Oracle would search for a local object instead of the remote one.

Correct Answer:

scott.employee@wgu2021

Why Other Options Are Wrong:

scott.employee refers to the employee table owned by Scott in the local database. Without the @wgu2021 database link, it never connects to the remote database and therefore cannot access the remote object.

employee by itself refers to a table named employee in the current user’s schema of the local database. It contains no schema qualifier or database link, so it cannot reach the remote object.

scott.employee@test specifies a database link named test, which does not exist in the scenario. Because the database link is named wgu2021, using @test will result in an error and will not resolve to the remote employee table.

Explanation:

DBUA retrieves the list of databases from the Oracle Local Registry (OLR) file, which is stored with a name format of host_name.olr. This file contains essential cluster and database configuration information used by Oracle utilities to identify databases on the host. DBUA reads the OLR to automatically display the databases that can be upgraded, making host_name.olr the correct source file.

Correct Answer:

host_name.olr

Why Other Options Are Wrong:

tnsnames.ora

This file contains network service names and connect descriptors for clients to establish connections to Oracle databases over the network. It is used for client connection resolution, not for listing local databases for an upgrade operation.

glogin.sql

This is a SQLPlus global login script that executes when a SQLPlus session starts. It can set environment settings or run startup commands, but it does not store or provide a list of databases to the Database Upgrade Assistant.

sqlnet.ora

The sqlnet.ora file contains network configuration parameters that control Oracle Net features such as encryption, authentication, and connection timeout settings. It plays no role in identifying or listing databases for DBUA upgrades.

Explanation:

Every Oracle instance requires the Database Buffer Cache, Shared Pool, and Log Buffer to operate correctly. The Database Buffer Cache temporarily stores data blocks read from disk, improving read/write performance. The Shared Pool stores parsed SQL statements, PL/SQL code, and dictionary information needed for query execution. The Log Buffer holds redo entries before they are written to redo log files, ensuring transaction consistency and recoverability. Together, these structures form the mandatory core components of the SGA.

Correct Answer:

All of the above

Why Other Options Are Wrong:

Database buffer cache

While essential, the Database Buffer Cache alone is not sufficient to run an Oracle instance. Other SGA structures like the Shared Pool and Log Buffer are also required for SQL execution and transaction management.

Shared pool

The Shared Pool is critical for caching SQL statements and metadata, but it cannot function alone. Without the Database Buffer Cache and Log Buffer, the instance cannot perform essential data operations or maintain transaction integrity.

Log buffer

The Log Buffer ensures redo entries are temporarily stored before being written to redo log files. While necessary, it alone does not meet the requirement for a fully functional SGA. The instance also needs the Database Buffer Cache and Shared Pool to operate properly.

Explanation:

The DIAGNOSTIC_DEST parameter specifies the base directory for all Oracle diagnostic files, which include the alert log, trace files, and incident information. By setting DIAGNOSTIC_DEST, Oracle automatically places the alert log inside the appropriate trace directory under this location. This parameter centralizes diagnostic data management and allows administrators to easily control where key diagnostic files are stored without needing to set multiple separate parameters.

Correct Answer:

DIAGNOSTIC_DEST

Why Other Options Are Wrong:

AUDIT_FILE_DEST defines the location where audit trail files are written when database auditing is enabled. These audit records track security-related database activities and are not related to the alert log. Changing this parameter only affects audit file storage and has no influence on where the alert log is kept.

LOG_ARCHIVE_DEST specifies the directory where archived redo log files are stored for recovery purposes. These redo logs are critical for point-in-time recovery but are completely different from the alert log, which records database events and messages. Therefore, this parameter does not determine the alert log location.

CORE_DUMP_DEST determines where core dump files are written in the event of an Oracle process failure. Core dumps are low-level diagnostic files used for debugging crashes and are unrelated to the routine alert log. Adjusting this parameter will not affect where the alert log is placed.