Most frequently Asked Oracle 19c Interview Questions

1. What experience do you have with Oracle 19c?
2. How familiar are you with setting up and administering Oracle 19c?
3. What challenges have you faced when working with Oracle 19c?
4. Describe how you would go about troubleshooting an issue with Oracle 19c?
5. How comfortable are you with SQL and PL/SQL programming for Oracle 19c?
6. How would you recommend best practices for using Oracle 19c in a high-availability environment?
7. What strategies have you used to optimize performance in Oracle 19c?
8. How have you employed security measures when dealing with Oracle 19c?
9. In your experience, what are the most common problems that come up with Oracle 19c?
10. How have you used Oracle 19c Enterprise Manager or Cloud Control to manage your database?
11. What does your experience tell you about maintaining and patching Oracle 19c?
12. How would you handle complex data structures in Oracle 19c?

What experience do you have with Oracle 19c?

An advanced database that is widely used for enterprise data management.
I have experience creating and managing databases, optimizing queries, deploying new features, and troubleshooting issues.
I'm also familiar with writing and debugging SQL code, as well as automating database processes with shell scripting and Python.
In terms of code snippets, I am comfortable working with a variety of Oracle programming languages, including PL/SQL, SQL, and Java.
Here is an example of a PL/SQL stored procedure that I created to access a database table:

CREATE OR REPLACE PROCEDURE Get_Employees AS
  employee_records employees%ROWTYPE; 
BEGIN
  SELECT * INTO employee_records 
    FROM employees;

  DBMS_OUTPUT.PUT_LINE('Number of employees in database: ' || employee_records.COUNT);
END Get_Employees;

This procedure will retrieve the total number of entries from the 'employees' table and give a total count as an output message using the DBMS_OUTPUT package.
This is just one of many examples of the types of coding tasks I can perform with Oracle 19c.

How familiar are you with setting up and administering Oracle 19c?

The basics of setting up and administering Oracle 19c are not too difficult but require some knowledge about the platform.
To start with, you will need to make sure that your computer meets the system requirements for running Oracle 19c.
Additionally, you will also need to have the correct software installed on your machine.
Once these steps have been taken care of, you can begin the installation process.
This involves downloading the Oracle 19c installer from Oracle's website and then following the instructions that are provided in the installer wizard.
After the installation is complete, you will then be able to configure the database settings.
This involves creating a database administrator user, setting up security settings, and establishing the tablespace storage.
You will also need to create and manage schemas, which will determine the structure of the data within the database.
You can do this through the use of SQL commands.
Finally, you will need to back up the database by using the Oracle Recovery Manager (RMAN).
This will provide you with an easy way to restore the database in case something goes wrong.
To provide a bit of code snippet, here is an example of a SQL query to create a schema:

CREATE SCHEMA author_schema AUTHORIZATION author_id; 
This will create a new schema, which you can name whatever you like, with its authorized user as 'author_id'.

What challenges have you faced when working with Oracle 19c?

Working with Oracle 19c can be challenging in a variety of ways.
One of the most common challenges is figuring out how to optimize queries for performance.
This is especially necessary for large datasets as query optimization can help to ensure that less resources are utilized.
Additionally, working with data types can be particularly tricky, as some datatypes may not be supported or require specific workarounds.
To help alleviate these challenges, it's always a good idea to utilize indexes whenever possible.
Creating indexes for the columns that are used regularly in your queries will help to speed up query execution.
Additionally, ensuring that your database is properly normalized and making use of constraints such as unique indexes and primary keys, will help keep your database organized and efficient.
Finally, you can also make use of stored procedures to increase performance.
For example, if you have a query that requires you to pull data from multiple tables, it's best to create a stored procedure to do this.
Not only will this improve performance, it will also help to make your code more organized and maintainable.
Here is an example of a query written as a stored procedure :

```CREATE OR REPLACE PROCEDURE find_data (v_id IN NUMBER)
IS
BEGIN
   SELECT a.*
   FROM tableA a
   JOIN tableB b
   ON a.id = b.id
   WHERE b.other_id = v_id;
END;
/
```

These are just some of the general techniques for optimizing Oracle 19c.
Additionally, there are many more tips and tricks that can be used depending on your specific needs.

Describe how you would go about troubleshooting an issue with Oracle 19c?

I would approach troubleshooting an issue with Oracle 19c using a methodical approach.
First, I would identify the issue by examining all of the available data and diagnostics around it.
Then, I would test possible solutions to the problem and use trial and error to find a solution.
Once I have identified the issue, I would then look for ways to prevent it from occurring again.
For instance, if the issue is related to incorrect permissions, I would check the system to ensure that the proper permissions are set up for all users and groups that may be accessing the database.
If I am looking for a code-based solution, I would examine where the error occurs in the code and then systematically work through each line, testing to see which ones produce the correct result.
Finally, I would review the code and look for any potential areas of improvement or optimization.
In addition to the above steps, I would also include a code snippet in my troubleshooting efforts, such as using PL/SQL to query a diagnostic table or review a current session.
Having this code snippet handy helps make troubleshooting easier and more efficient.

How comfortable are you with SQL and PL/SQL programming for Oracle 19c?

I'm quite comfortable with SQL and PL/SQL programming for Oracle 19c.
The basics of both of these languages are relatively straightforward, but in order to leverage the full potential of Oracle 19c, it's important to understand the more advanced functions available.
For example, one of the most powerful features of Oracle 19c is its ability to join multiple tables together, allowing users to access data from multiple tables with a single SQL statement.
This allows a single query to produce complex data combinations that would not be possible without the join functionality.
Additionally, Oracle 19c also offers a variety of built-in functions that make it easier to perform certain operations such as string manipulation, date calculation, and basic arithmetic.
Here is a sample PL/SQL statement that illustrates how to join two tables and then calculate the average of a numerical column:

SELECT AVG(column_name) 
FROM table1 t1 JOIN table2 t2 
ON t1.id = t2.id
WHERE t2.value > 0;

Overall, Oracle 19c provides a wide range of powerful tools that significantly increase the capabilities of developers.
With its robust feature set, Oracle 19c is a great choice for any enterprise development project.

How would you recommend best practices for using Oracle 19c in a high-availability environment?

When setting up an Oracle 19c high-availability environment, the best practices involve several steps.
Firstly, it's important to ensure that you have a good foundation in place by configuring redundancy for all components involved in the system, including databases, servers and network components.
Additionally, best practices also include setting up redundant storage solutions such as RAID, as well as using Oracle Clusterware and other clustering solutions.
In terms of performance, Oracle 19c offers many features to ensure optimal database response times.
This includes tuning memory usage, leveraging the Oracle Real Application Clusters (RAC) technology, and configuring parameters for optimal utilization of the CPU and disk I/O.
Moreover, it's important to monitor and analyze the database performance in order to identify any potential performance issues.
To facilitate quick recovery in the case of a failure, it is also beneficial to use a combination of replication techniques such as Data Guard, various backup mechanisms, and data archiving to ensure availability of data in the event of an outage.
Finally, another important best practice is to implement proactive monitoring of the system by using scripts or special tools.
This enables administrators to detect any problems quickly and proactively address them before they lead to major outages.
Here is a code snippet for setting up a high-availability cluster with Oracle 19c:

$ srvctl add service -db <DB_Name> -server <Server_Name> -service <Service_Name> -pstart -s
$ srvctl modify service -db <DB_Name> -server <Server_Name> -service <Service_Name> -pstop -s
$ srvctl start service -db <DB_Name> -server <Server_Name> -service <Service_Name> -f

What strategies have you used to optimize performance in Oracle 19c?

To optimize performance in Oracle 19c, it's important to ensure that the system is properly sized and configured through a few different methods.
The first would be to tune the database itself.
This involves setting the necessary parameters, making sure enough memory is allocated to the SGA and PGA, and running proper usage metrics.
Additionally, it's also important to take advantage of any features specific to Oracle 19c that will aid in boosting performance.
By utilizing Advanced Index Compression, Multi-Index Compression, In-Memory Parallel Query Option, Partition Exchange Load, and other tools, database administrators can get the most out of their Oracle 19c databases.
Another strategy for optimizing performance is improving queries.
This includes using bulk operations, identifying long-running queries, increasing parallelism, and utilizing indexes.
It can also be helpful to use a SQL monitoring tool to gain insights into which queries take the longest and can be improved.
Finally, using the Oracle 19c Optimizer Statistics Advisor feature can help identify the best execution plan for queries and tune the database.
Code snippet example:

SELECT /*+ parallel(4) */ COUNT(*) FROM SALES_TABLE;

This code snippet enables the query to be executed with four parallel threads, thus improving the performance of the query.

How have you employed security measures when dealing with Oracle 19c?

Oracle 19c is equipped with the latest security features to ensure that data and system access remain secure.
On the server side, Oracle 19c provides an additional authentication mechanism called Oracle Advanced Security.
This feature uses a combination of authentication methods such as two-factor authentication and password vaulting to create an extra layer of security for users.
Oracle also provides a robust set of TDE (Transparent Data Encryption) features which allow data stored in the database to be encrypted for enhanced protection.
On the application side, Oracle 19c provides an additional layer of security through the use of Application Contexts.
With Application Contexts, developers can create custom security policies specifically for their application, making it easier to prevent malicious activity.
To ensure security on all fronts, Oracle 19c also offers auditing tools and audit reports to monitor user activity and track security violations.
The following code snippet shows how Oracle 19c can help secure user access:

-- Set up new application context
EXEC DBMS_SESSION.SET_CONTEXT('MyApplicationContext', 'Login_User', USER);
-- Set up an audit policy
EXEC DBMS_AUDIT_MGMT.SET_AUDIT_POLICY( audit_policy_name=>'MyAuditPolicy', enable=>TRUE, audit_options=>DBMS_AUDIT_MGMT.ALL_ACTIONS);
-- Enforce new security policies
EXEC DBMS_RLS.ENFORCE_RLS(object_schema=>'MY_SCHEMA',object_name=>'MY_TABLE',policies=>'MyApplicationContext=MY_SCHEMA.SESSION_POLICY');

In your experience, what are the most common problems that come up with Oracle 19c?

When it comes to Oracle 19c, one of the most common problems is related to the Oracle Database Exadata Cloud Service.
This cloud service provides a platform for the Oracle Database that allows users to access their data securely and efficiently.
The issue arises when users are unable to properly set up their environment to better manage their data.
To configure the environment correctly, one must ensure that the proper patches and updates are applied to the Oracle 19c instance.
Furthermore, the environment should be configured so that the database can run optimally.
If done correctly, this will help reduce the risk of potential performance issues or security breaches.
In addition, it is important to ensure that the application is able to connect to the database via JDBC drivers.
To properly enable the connection between the application and Oracle 19c, users should use the following code snippet:

String connectionURL = "jdbc:oracle:thin:@hostname:port:sid";
Connection connection = DriverManager.getConnection(connectionURL, username, password);

By ensuring that the application is able to connect to the Oracle 19c instance with the proper JDBC drivers, users can take full advantage of the Oracle Database Exadata Cloud Service.

How have you used Oracle 19c Enterprise Manager or Cloud Control to manage your database?

Oracle 19c Enterprise Manager and Cloud Control are powerful tools for managing databases.
They enable DBAs to perform many tasks such as monitoring, automating administration, patching, provisioning, deploying, and diagnosing Oracle systems.
Additionally, they provide an easy-to-use interface with intuitive dashboards for visualizing the health of your database.
One of the key features of Oracle's databases is the ability to use the Enterprise Manager or Cloud Control to manage them.
With these tools, you can quickly identify any performance issues, analyze data from various sources, and make decisions to ensure that the database is running optimally.
For example, you can measure efficiency by comparing multiple queries, set up thresholds and alerts if a certain metric exceeds it, and monitor trends in query plan evolution.
In addition to these basic features, Oracle 19c Enterprise Manager and Cloud Control also come with advanced capabilities such as Database Replay, which allows for replaying workloads for testing purposes.
This tool is particularly useful for optimizing and fine-tuning databases prior to deployment.
You can also use the Diagnostic and Tuning Packs bundled with Oracle 19c to identify problem areas in the database and tune its performance.
The code snippet below shows how to use Oracle 19c Enterprise Manager or Cloud Control to monitor the performance of the database:

```
BEGIN
  SELECT * FROM V$DIAG_INFO;
END;
```

This query will return various performance metrics that can be used to analyze the status of the database.
By using Oracle 19c Enterprise Manager or Cloud Control, DBAs can leverage the powerful functions and capabilities to efficiently manage their databases.
These tools make it easier to identify problems, optimize performance, and ensure that the database is always running smoothly.

What does your experience tell you about maintaining and patching Oracle 19c?

My experience with maintaining and patching Oracle 19c is that it is a process that requires attention to detail and a good understanding of both the language and the underlying system.
In order to keep your Oracle 19c installation up-to-date, you will need to make sure all of the necessary patches are applied.
This can be done by installing the latest patch set and then applying any patches that have been released since then.
Additionally, you will need to take steps to ensure that any new patches do not cause any issues for your existing databases or applications.
In my experience, the best way to maintain and patch Oracle 19c is to schedule regular maintenance windows and use release notes to determine which patches need to be applied.
This will allow you to stay on top of the latest releases and ensure that your environment remains secure and stable.
Additionally, you can use various code snippets such as shell scripts and SQL scripts to automate the patching process, making the task easier and faster.
Overall, maintaining and patching Oracle 19c requires diligent effort and detailed attention to ensure that your system remains secure and stable.
By scheduling regular maintenance windows and automating any necessary tasks, you can ensure that your system remains up-to-date and secure.

How would you handle complex data structures in Oracle 19c?

Working with complex data structures in Oracle 19c can be a bit tricky, but with the right knowledge and approach, it can be done efficiently.
The best way to handle these types of data structures is to use a combination of relational database design (RDBMS) and object-oriented programming (OOP).
You can also use PL/SQL, which is a procedural language extension of SQL.
Once you have set up your data structures, you will then need to start creating your code.
To make the process simpler, many languages provide APIs that allow you to store, sort, and manipulate data stored in databases.
One such API is Oracle's Data Access Language (DAL), which provides functions such as INSERT, UPDATE, and DELETE.
Here is a snippet of code that shows how to insert a record into the database with DAL:

INSERT INTO table_name (column1, column2, ... ) VALUES (value1, value2, ... ); 

This simple command can be used to store the complex data you want to use in Oracle 19c.
Other API functions can be used for sorting and manipulating data, allowing you to work more efficiently when working with complex data structures.
With the right knowledge and approach, you can successfully handle complex data structures in Oracle 19c.