Download Oracle Database 19c: Performance Management and Tuning.1z0-084.Actual4Test.2026-04-09.79q.tqb

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, 19cThese changes are recommended based on Oracle's best practices for managing large tables and reducing I/O waits, ensuring better performance and efficiency.

The ORA-15505 error indicates that the instance encountered errors while trying to access the specified directory. This could be due to:A: Insufficient privileges: The user attempting to start the workload capture might not have the required permissions to execute the DBMS_WORKLOAD_CAPTURE package or to read/write to the directory specified.E: Accessibility: The database instance may not be able to access the directory due to issues such as incorrect directory path, directory does not exist, permission issues at the OS level, or the directory being on a file system that's not accessible to the database instance.References:* Oracle Database Error Messages, 19c* Oracle Database Administrator's Guide, 19c

ADDM (Automatic Database Diagnostic Monitor) is a key Oracle diagnostic tool that analyzes performance data captured by AWR (Automatic Workload Repository) and provides insights into performance issues. In a PDB (Pluggable Database), ADDM can provide recommendations for various types of performance issues.Why A. I/O capacity limits is correct:* ADDM evaluates the performance of a database and identifies I/O bottlenecks that could be impacting query performance.* I/O capacity limits occur when the database cannot handle the I/O workload effectively, which could be due to disk contention, inadequate I/O throughput, or hardware limitations.* ADDM reports such issues and suggests remedies like tuning SQL queries, redistributing I/O workloads, or upgrading storage systems.Why D. Top SQL statements is correct:* One of the critical capabilities of ADDM is identifying high-resource-consuming SQL statements (Top SQL) that are impacting database performance.* For PDBs, ADDM provides specific recommendations to optimize these SQL statements, such as improving execution plans, adding indexes, or rewriting queries.Why Other Options Are Incorrect:* B. Excessive checkpoint writes:* While excessive checkpoint writes can occur, ADDM typically focuses on higher-level performance problems like I/O issues or top SQL rather than specific low-level operational events like checkpointing. Excessive checkpoint writes are not commonly reported directly for PDBs by ADDM.* C. SGA sizing issues:* ADDM does not directly analyze or provide recommendations for SGA (System Global Area) sizing issues at the PDB level because SGA is managed at the CDB (Container Database) level.PDBs share the SGA of the CDB.* E. User I/O waits:* While user I/O waits are captured in performance metrics, ADDM typically groups them under broader issues like I/O capacity limits. It does not specifically report on "user I/O waits" as a standalone problem.Key Features of ADDM for PDBs:* Identifying Top SQL Statements impacting performance.* Reporting I/O issues, including capacity limits and contention.* Highlighting inter-PDB resource contention within the same CDB.References to Oracle Documentation:* Oracle Database 19c Performance Tuning Guide:* Section: Using ADDM for Pluggable Databases.* Details the types of performance issues ADDM reports for PDBs.* Automatic Database Diagnostic Monitor (ADDM) Concepts:* Highlights ADDM's ability to analyze I/O, SQL performance, and resource utilization.

https://docs.oracle.com/en/database/oracle/oracle-database/21/tgsql/sql-tuning-advisor.html#GUID-8E1A39CB-A491-4254-8B31-9B1DF7B52AA1The goal is to reduce the db file scattered read waits, which are associated with full table scans. These are I/O operations where Oracle retrieves data blocks scattered across the disk, typically when large amounts of data are read inefficiently. Running the SQL Tuning Advisor analyzes the workload and provides tuning recommendations. Let's evaluate the options.Why A. Recommendations regarding the creation of additional indexes is correct:* Full table scans (which cause db file scattered read) often occur because suitable indexes are missing.* The SQL Tuning Advisor can identify queries that would benefit from indexes and recommend creating them. Indexes allow the database to access data more efficiently using row lookups, reducing the need for full table scans.Why B. Recommendations regarding rewriting the SQL statements is correct:* Sometimes, poorly written SQL statements cause inefficient execution plans that lead to db file scattered read.* SQL Tuning Advisor can recommend SQL rewrites to make better use of indexes, avoid full table scans, or optimize joins. For example:* Rewriting predicates to use indexed columns.* Using hints to guide the optimizer.Why Other Options Are Incorrect:* C. Recommendations regarding the creation of materialized views:* Materialized views are typically recommended to optimize complex queries involving aggregations or joins, not to address db file scattered read directly. They are less relevant for solving I/O issues caused by full table scans in this context.* D. Recommendations regarding the creation of SQL Patches:* SQL Patches are used to influence the execution plan for specific SQL statements. While SQL Patches can potentially fix performance issues, the SQL Tuning Advisor focuses on improving SQL and database design rather than patching queries.* E. Recommendations regarding partitioning the tables:* Partitioning tables can improve query performance, especially for very large datasets. However, this is a database design-level recommendation and is not typically provided by SQL Tuning Advisor. Partitioning would not directly target db file scattered read.How SQL Tuning Advisor Helps:The SQL Tuning Advisor provides actionable recommendations, such as:* Creating indexes to reduce full table scans.* Rewriting SQL to optimize the execution plan.* Improving statistics to help the optimizer make better decisions.References to Oracle Documentation:* Oracle Database 19c Performance Tuning Guide:* Section: Using SQL Tuning Advisor to Optimize Workloads.* Explains recommendations for indexes and SQL rewrites to reduce I/O.* Understanding Wait Events:* Details about db file scattered read and how to address it.

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 you intend 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

Given that index range scan operations on IX_SALES_TIME_ID are 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 using ADVANCED COMPRESSION can 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 the SALES table 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 in IX_SALES_TIME_ID as a hash partitioning key for the SALES 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

The objective of performance tuning in Oracle Database is to meet specific performance goals. These goals may vary based on the requirements of the system and business objectives. Let's evaluate each option in detail to understand why E is correct and others are not.Option Analysis:* A. When the allocated budget for performance tuning has been exhausted* Why it's incorrect:* Tuning should not stop simply because the budget is exhausted. If performance goals are not met, the database might still experience performance issues, impacting the end-users or business-critical processes. Budget is a constraint, but it shouldn't define when tuning stops.* B. When all the concurrency waits are eliminated from the Top 10* Why it's incorrect:* Concurrency waits (such as locks or latches) are just one aspect of database performance tuning. Eliminating these waits does not necessarily mean the system meets its performance goals. Other factors like query optimization, I/O performance, and CPU usage might still need attention.* C. When the buffer cache and library cache hit ratio is above 95%* Why it's incorrect:* Cache hit ratios are often overemphasized as a performance metric. While a high hit ratio indicates efficient memory usage, it doesn't guarantee optimal performance. A high ratio could still mask inefficient SQL queries, suboptimal execution plans, or other bottlenecks.* D. When the I/O is less than 10% of the DB time* Why it's incorrect:* While reducing I/O is beneficial, it is not always a sufficient indicator that tuning can stop.Certain workloads may inherently have high or low I/O percentages. The real question is whether the database is meeting its required service levels, not just reducing I/O.* E. When the tuning goal has been met* Why it's correct:* The purpose of performance tuning is to meet the specific performance goals set by the business or the database administrators. Once the database meets these goals (e.g., query response times, throughput requirements, or SLA commitments), tuning can stop. This ensures effort is focused on achieving measurable outcomes, rather than chasing arbitrary metrics.The Importance of Defining a Tuning GoalPerformance tuning should be driven by clear goals such as:* Reducing response time for specific critical queries.* Meeting SLAs for application performance.* Supporting a target number of concurrent users.* Reducing resource contention for improved scalability.Tuning should stop once these goals are achieved because continuous tuning without purpose can lead to unnecessary complexity and resource usage.Reference to Oracle Documentation:* Oracle Database 19c Performance Tuning Guide:* Section: Establishing Performance Goals and Metrics.* Discussion on focusing tuning efforts on business requirements and goals.* Oracle Database Concepts Guide:* Best practices for balancing performance improvements with system complexity.

For this SQL statement and output, we can analyze the EVENT column to understand the type of wait:B: The event "SQL*Net message from client" typically indicates that the session is waiting for a response from the client. This can be due to a network issue, user response, or an application processing delay.E: The event "SQL*Net message from client" also implies that the session is idle waiting for the client (a user or an application) to send a request to the server. This event usually indicates that the session is not actively working but is instead waiting for the next command.F: The wait event "enq: TX - row lock contention" suggests that session 9822 is waiting for a row-level lock held by another session. If the holding session issues a COMMIT or ROLLBACK, the lock will be released, and session 9822 will stop waiting. Since this session is experiencing row lock contention, it implies it's waiting for a specific transaction to complete.References:* Oracle Database Reference, 19c* Oracle Wait Events Documentation

The CONCATENATION step in an execution plan is introduced during the SQL Transformation phase. This phase is part of the optimizer's query transformations which can include various techniques to rewrite the query for more efficient execution. The CONCATENATION operation is used to combine the results of two separate SQL operations, typically when there is an OR condition in the WHERE clause, as seen in the provided query.References:* Oracle Database SQL Tuning Guide, 19c* Oracle Database Concepts, 19c