If you’re expanding your business globally or thinking about improving your database system, sooner or later you may take into consideration hiring an Oracle Database developer.
Oracle database is one of the most trusted software to manage app databases and users’ interactions. In 1977, Lawrence Ellison developed this software as part of a relational database framework where users can directly access data objects. The system can manage the inputs from different databases as a unit, making Oracle one of the best software to manage different databases.
By definition, Oracle is a relational database management system (RDBMS) by Oracle Corporation. Global enterprises use this software to manage and process data across wide and local area networks. Oracle database uses its own network components to open communications across networks.
Looking at the enterprise database market, Oracle DB is the stronger rival of Microsoft’s SQL server. With a similar structure, these systems are the most reliable choice when it comes to database administration. How to make sure to hire the best developer for your team?
What Can You Do With Oracle?
Oracle DB runs on major platforms such as Windows, UNIX, Linux and Mac OS. What makes this software unique is the architecture split between the logical and the physical. In simple words, it allows the user to send inputs from any location without affecting the data collection.
With this system, for large-scale distributed computing – the ill-famed grid computing – the data location is irrelevant and transparent to the user. You can modify the modular physical structure without affecting the database’s functionalities, its data, or users. This structure is so solid that failures bringing down the database can be only local, while the network of storage resources stay intact.
The ability to share resources between databases creates a flexible data network that can be adjusted based on your business’s demand without degrading the service. Based on the scale of your project, Oracle offers different editions to suit your business plans:
- Enterprise Edition includes all features from superior performance and security.
- Standard Edition offers basic functions for the user without requiring Enterprise Edition’s full package.
- Express Edition (EX) is the lightweight and free edition for Linux and Windows.
- Oracle Lite is for mobile devices.
OracleDB Pros and Cons
Pros of Oracle DB
1. Enterprise Grid Computing
This type of computing helps you manage your data and applications in a cost-effective and flexible way and “creates large pools of industry-standard, modular storage, and servers.” One of the reasons this type of architecture functions so well is that each new system can be “rapidly provisioned from the pool of components.”
A primary benefit of OracleDB is that it can simply add or reallocate data when necessary from the resource pools, eliminating the need for peak workloads. Additionally, the split system between the logical and physical structures allows you to manage the physical data storage without changing the logical storage structures’ access.
2. Portability, Backup & Recovery
Running on major platforms, Oracle runs on almost 20 networking protocols and hundreds of hardware platforms. This popularity makes it easier for Oracle DB developers to write an application and make changes to it.
This flexibility also guarantees an entire online backup and recovery. As we said earlier, the split structure protects the core network allowing failure only on local databases. With an Oracle database, it is easy to set a point-in-time recovery maintaining speed and high performance.
3. Customization and Organization
Unlike other types of storage systems, Oracle has an advanced optimizer that can model data in many different ways, including nested subqueries and recursive queries.
OracleDB can be constantly modified to fit the database and hardware to the specific needs of your business, with a wider selection of variables and design layouts.
Plus, OracleDB allows you to reuse the code interacting with data objects and maintaining a clean code. For example, MySQL developers write their code outside of the database, giving them slightly less control.
4. Transparent Multiple Database Support
Additionally, Oracle database gives its users plenty of tools and guidance to fully understand what is going on inside your software and hardware. This transparency allows you to collect feedback and adjust settings.
Beyond this, Platform as a Service (PaaS) work is straightforward in OracleDB because of the advanced partitioning and sub partitioning implementation offered, giving plenty of options to specify your business solutions.
Cons of OracleDB
The first con is Oracle’s complexity. If your users lack technical skills, Oracle may not be the choice. The same goes for you. If your company is seeking a database easy to use, Oracle requires specialized installation and maintenance skills.
OracleDB’s steep learning curve doesn’t compare to its competitor MySQL. For this reason, if you need an expert with both types of databases, it’s even more essential to find an expert to use Oracle.
2. High Costs
Everything in this world has a price, and Oracle’s one is pretty high. Oracle DB products’ prices can increase up to ten times compared to MS SQL Server competitors. However, many users find that its advantages outweigh the cost of customizing the software.
3. Hard to Manage
As we mention, Oracle DB is a very complex system. Its flexibility to manage data collection and database networking require technical skills for both users and developers. That’s why this system is not preferable for small or medium-sized businesses. But if your company needs a large database, Oracle DB is what you want.
The system disadvantages are essential to consider, but they all have one solution: hiring a great Oracle DB developer.
OracleDB Developer vs DBA Developer
When it comes to hiring, we need to make a distinction. If you need someone to develop and program your database network, you are looking for an OracleDB developer.
Database developers take over from analysts and designers. Examining the high level of documentation produced in the initial stage, they create the database application building all the components — tables, queries, reports, etc.
If you need someone to help users with daily issues once the database is running, you need an Oracle DBA developer. Database administrators take care of security monitoring who is accessing the data. Additionally, DBA developers are responsible for running the whole process, collaborating across different departments.
Whether you need a developer or an administrator, it’s important to ask the right things. Here are the best Oracle interview questions for both roles:
Interview Question for an Oracle DB Developer
1. Explain SAVEPOINT and give an example
In Oracle, you can name and mark your current spot in the transaction’s processing with the SAVEPOINT statement. All savepoints will be erased with a simple rollback or commit. Additionally, “when you roll back to a savepoint, any savepoints marked after that savepoint are erased,” although the one that you roll back does remain.
Your OracleDB developer for hire should also know that they can use savepoints to undo parts of a transaction rather than the whole thing with the ROLLBACK TO statement. Savepoint names can be reused; this simply makes the savepoint move from its old position to the point in which it’s renamed.
OracleDB marks savepoints implicitly before executing an INSERT, UPDATE, or DELETE statement. Then, if the statement happens to fail, the database automatically performs a rollback to this implicit savepoint.
2. Briefly, explain the OracleDB ANALYZE statement
The analysis statement is a particularly useful one for any OracleDB developer to know. It collects or deletes statistics about a particular index or index partition, table or table partition, index-organized table, cluster, or scalar object attribute.
With this statement, you can also identify migrated and chained rows of a table or cluster as well as validate the structure of an index or index partition, table or table partition, index-organized table, cluster, or object reference (REF).
3. Explain a hash cluster in Oracle and give an example
The reason that your OracleDB developer should know about sorting tables in a hash cluster is because it’s used as an alternative to a non-clustered table with an index or an index cluster to improve the performance of data retrieval.
It works by physically storing the rows of a table in a hash cluster. Then, when you need to retrieve the data, it performs this action according to the results of a hash function. Hash values, which are numeric values, generated by OracleDB’s hash function, and based on specific cluster key values.
A minimum of two I/Os is necessary to find or store a row in an indexed table or cluster, although there are typically more than two. However, no I/O is required to locate a row in a hash cluster because the database utilizes a hash function; although, to read or write a row in a hash cluster, a minimum of one I/O operation is necessary.
According to Oracle, the most useful times to use a hash cluster are under the following conditions:
- If the majority of queries on the cluster key are equality queries:
SELECT … WHERE cluster_key = …;
- You have static-sized tables in the hash cluster and can determine exactly how much space is required for the tables. One of the downfalls of tables in a hash cluster is that the performance can suffer if they require more space than what was initially allocated for the cluster.
Ask your OracleDB developer for hire to perform an example of creating a hash cluster. In the following example by Oracle, trial_cluster is the name of the created cluster that holds the trial table. The trial no column is the cluster key, and the lower statement creates the table in the cluster.
CREATE CLUSTER trial_cluster (trialno NUMBER(5,0)) TABLESPACE users STORAGE (INITIAL 250K NEXT 50K MINEXTENTS 1 MAXEXTENTS 3 PCTINCREASE 0) HASH IS trialno HASHKEYS 150; CREATE TABLE trial ( trialno NUMBER(5,0) PRIMARY KEY, …) CLUSTER trial_cluster (trialno);
4. What is the difference between a hot backup and a cold backup with Oracle?
Of course, we all know that backups are vitally important for your information. Because of this, your OracleDB developer should know them very well. A cold backup is performed when the database is in a shutdown state, and there is no user activity currently on the system. This type of backup creates a full copy of the database, allowing you to fully restore it if necessary.
A hot backup, on the other hand, is taken while the database is active. This type of saving provides you with an online backup with all files of the database copied. It doesn’t take care of active transactions, but there can be changes to the database during the copy.
Interview Questions for an OracleDBA Developer
1. To create a responsible file to speed up the installation of a database, how would you prepare the file?
A response file is a plain text file storing the options to create a database. You can create this file from scratch but it would take longer. It’s easier to customize manually installation media that come with a tempòate response file, which also contains notes about the parameters.
The most reliable way to create a response file, however, is Oracle Universal Installer. When you start the installer in ‘record’ mood every option at each step is saved in a response file in the correct format. Once the installer completes the record mode, you will have a response file with all the options set.
2. If a client forgets the password for the ‘SYSTEM’ user of his database and he cannot longer connect. How would you recover this admin password?
If other users have ‘DBA’ privileges, you can connect with them and change the password for the ‘SYSTEM’ user. Users with DBA privileges can change any user’s password, which is the easiest way but it may be not possible in any cases.
Without DBA users, the only way to access the database is using operating system privileges. At the operating system, the Oracle software runs under a specific user, usually named “oracle”. Also, you need a user group that the “oracle” user belongs to, usually called “dba”. The group can connect to the database with “SYSDBA” privileges in the operating system they belong to. So, you can ask the login to the system administrator for a server as an “oracle” user or any user who belongs to this “dba” group. Once in the operating system, you can connect to the database locally with SYSDBA privileges. After connecting to the database, you can change and reset the password for this system user.
3. What do you do to find out how many users are defined in the password file and their privileges?
To look in the password file, you need to query the ‘v$pwfile_users’ view to have information about existing users in the password file.
Here is how you execute the SQL query (Source: MindMajix.com):
Sql>SELECT * FROM v$pwfile_users;
The query above will return four columns for each user in the password file. The column names are USERNAME, SYSDBA, SYSOPER, and SYSASM.
- The USERNAME column shows the username of the user in the password file.
- The SYSDBA column shows whether the user has SYSDBA privileges or not.
- The SYSOPER column shows whether the user has SYSOPER privileges or not.
- The SYSASM column shows whether the user has SYSASM privileges or not.
4. What would be your main responsibilities of an Oracle DBA in an organization?
The main duty will be the organization of Oracle databases, which can involve writing code of a database from scratch. On a running system, the DBA developer is the only person able to shut down or start up the database. The DBA also creates new users and manages their privileges.
A DBA takes regular backup to ensure data safety and will restore the database from backups, monitoring the space usage and capacity planning for the database. Also, a DBA developer creates security policies and monitors database activities.
Ready To Hire the Best OracleDB Developer? DistantJob Comes to Your Rescue
These are some of the best questions for these two roles. If you need someone to develop a backend application, an OracleDB is the role you should be looking for. If you need someone that administrates the database, a DBA will take care of your database maintenance and users.
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