At ValidExamDumps, we consistently monitor updates to the Oracle 1Z0-084 exam questions by Oracle. Whenever our team identifies changes in the exam questions, objectives, focus areas or requirements, We immediately update our exam questions for both PDF and online practice exams. This commitment ensures our customers always have access to the most current and accurate questions. By preparing with these up to date and 100% exam domain coverage questions, our customers can successfully pass the Oracle Database 19c: Performance Management and Tuning exam on their first attempt without needing additional materials or study guides.
Other certification materials providers often include outdated or removed questions by Oracle in their 1Z0-084 exam. These outdated questions lead to customers failing their Oracle Database 19c: Performance Management and Tuning exam. In contrast, we ensure our questions bank includes only precise and up-to-date questions. Our main priority is your success in the Oracle 1Z0-084 exam, not profiting from selling obsolete exam questions in PDF or Online Practice Test.
Examine this statement and its corresponding execution plan:
Which phase introduces the CONCATENATION step?
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.
Oracle Database SQL Tuning Guide, 19c
Oracle Database Concepts, 19c
Which two types of performance problems are reported by ADDM for PDBS?
The Automatic Database Diagnostic Monitor (ADDM) analyzes and reports on various types of performance problems. For Pluggable Databases (PDBs), it can identify issues such as I/O capacity limits which may hinder the overall performance by causing bottlenecks. Additionally, ADDM can report on user I/O waits, which can indicate performance issues related to the time it takes for user queries to read data from the disk.
Oracle Multitenant Administrator's Guide, 19c
Oracle Database Performance Tuning Guide, 19c
Examine this statement and output:
Which two situations can trigger this error?
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.
Oracle Database Error Messages, 19c
Oracle Database Administrator's Guide, 19c
Multiple sessions are inserting data concurrently into a table that has an LOB column.
At some point in time, one of the sessions cannot find available space in the LOB segment and needs to allocate a new extent.
Which wait event will be raised in the other sessions that need space in the LOB column?
When sessions concurrently insert data into a table with an LOB column and one session needs to allocate a new extent because it cannot find available space, the wait event associated with this contention is 'enq: HW - contention'. The HW stands for High Water Mark which is related to space allocation in the database segment. When a session needs to allocate a new extent, it may raise this wait event in other sessions that are also attempting to allocate space in the same LOB segment.
Reference
Oracle Database 19c Reference Guide - enq: HW - contention
You manage a 19c database with default optimizer settings.
This statement is used extensively as subquery in the application queries:
SELECT city_id FROM sh2.sales WHERE city_id=:Bl
You notice the performance of these queries is often poor and, therefore, execute:
SELECT city_id,COUNT(*) FROM sh2.sales GROUP BY city_id;
Examine the results:
There is no index on the CITY_ID column.
Which two options improve the performance?
In this scenario, creating an index and generating frequency histograms are two methods that can potentially improve performance:
A (Correct): Generating frequency histograms on the CITY_ID column can help the optimizer make better decisions regarding the execution plan, especially if the data distribution is skewed. Histograms provide the optimizer with more detailed information about the data distribution in a column, which is particularly useful for columns with non-uniform distributions.
B (Correct): Creating an index on the CITY_ID column would speed up queries that filter on this column, especially if it's used frequently in the WHERE clause as a filter. An index would allow for an index range scan instead of a full table scan, reducing the I/O and time needed to execute such queries.
C (Incorrect): While SQL profiles can be used to improve the performance of specific SQL statements, they are usually not the first choice for such a problem, and creating a profile does not replace the need for proper indexing or statistics.
D (Incorrect): Forcing the subquery to use dynamic sampling might not provide a consistent performance benefit, especially if the table statistics are not representative or are outdated. However, dynamic sampling is not as effective as having accurate statistics and a well-chosen index.
E (Incorrect): Adaptive plans can adjust the execution strategy based on the conditions at runtime. While they can be useful in certain scenarios, in this case, creating an index and ensuring accurate statistics would likely provide a more significant performance improvement.
Oracle Database SQL Tuning Guide: Managing Optimizer Statistics
Oracle Database SQL Tuning Guide: Using Indexes and Clusters
