top dba interview questions and answers job interview tips

Top 20 dba interview questions and answers

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Interview questions and answers – free pdf download of 30

Tell me about yourself?

This is probably the most asked question in dba interview. It breaks the ice and gets you to talk about something you should be fairly comfortable with. Have something prepared that doesn't sound rehearsed. It's not about you telling your life story and quite frankly, the interviewer just isn't interested. Unless asked to do so, stick to your education, career and current situation. Work through it chronologically from the furthest back to the present.


What are Schema Objects? Schema objects are the logical structures that directly refer to the database’s data. Schema objects include tables, views, sequences, synonyms, indexes, clusters, database triggers, procedures, functions packages and database links.


What Can You Do for Us That Other Candidates Can't?

What makes you unique? This will take an assessment of your experiences, skills and traits. Summarize concisely: "I have a unique combination of strong technical skills, and the ability to build strong customer relationships. This allows me to use my knowledge and break down information to be more user-friendly."


What are the advantages of views?

Provide an additional level of table security, by restricting access to a predetermined set of rows and columns of a table.Hide data complexity. Simplify commands for the user.Present the data in a different perspective from that of the base table.Store complex queries.


What is hash cluster? When can hash cluster used?

A row is stored in a hash cluster based on the result of applying a hash function to the row’s cluster key value. All rows with the same hash key value are stores together on disk.

Hash clusters are better choice when a table is often queried with equality queries. For such queries the specified cluster key value is hashed. The resulting hash key value points directly to the area on disk that stores the specified rows.


What is data block? How to define data block size?

Oracle database’s data is stored in data blocks. One data block corresponds to a specific number of bytes of physical database space on disk.

A data block size is specified for each Oracle database when the database is created. A database users and allocated free database space in Oracle data blocks. Block size is specified in init.ora file and cannot be changed latter.


What is a database instance? Explain. A database instance (Server) is a set of memory structure and background processes that access a set of database files. The processes can be shared by all of the users.The memory structure that is used to store the most queried data from database. This helps up to improve database performance by decreasing the amount of I/O performed against data file.


What is a deadlock? Explain. Two processes waiting to update the rows of a table, which are locked by other processes then deadlock arises.In a database environment this will often happen because of not issuing the proper row lock commands. Poor design of front-end application may cause this situation and the performance of server will reduce drastically.These locks will be released automatically when a commit/rollback operation performed or any one of this processes being killed externally.


What is SGA? The System Global Area in an Oracle database is the area in memory to facilitate the transfer of information between users. It holds the most recently requested structural information between users. It holds the most recently requested structural information about the database. The structure is database buffers, dictionary cache, redo log buffer and shared pool area.


What is a redo log? What is the function of redo log? What is the use of redo log information?

The set of redo log files for a database is collectively known as the database redo log.

The primary function of the redo log is to record all changes made to data.

The information in a redo log file is used only to recover the database from a system or media failure prevents database data from being written to a database’s data files.


What is a datafile? What are the characteristics of data files?

Every Oracle database has one or more physical data files. A database’s data files contain all the database data. The data of logical database structures such as tables and indexes is physically stored in the data files allocated for a database

A data file can be associated with only one database. Once created a data file can’t change size. One or more data files form a logical unit of database storage called a tablespace.


What is row chaining? In circumstances, all of the data for a row in a table may not be able to fit in the same data block. When this occurs, the data for the row is stored in a chain of data block (one or more) reserved for that segment.


What is database link? What are the types of database links?

A database link is a named object that describes a “path” from one database to another.

Private database link, public database link & network database link.


What is private database link, public database link, network database link?

Private database link is created on behalf of a specific user. A private database link can be used only when the owner of the link specifies a global object name in a SQL statement or in the definition of the owner’s views or procedures.

Public database link is created for the special user group PUBLIC. A public database link can be used when any user in the associated database specifies a global object name in a SQL statement or object definition.

Network database link is created and managed by a network domain service. A network database link can be used when any user of any database in the network specifies a global object name in a SQL statement or object definition.


What is an index? How it is implemented in Oracle database?

An index is a database structure used by the server to have direct access of a row in a table. An index is automatically created when a unique of primary key constraint clause is specified in create table command


What is Database Buffers? Database buffers are cache in the SGA used to hold the data blocks that are read from the data segments in the database such as tables, indexes and clusters DB_BLOCK_BUFFERS parameter in INIT.ORA decides the size.


What is a temporary segment? Temporary segments are created by Oracle when a SQL statement needs a temporary work area to complete execution. When the statement finishes execution, the temporary segment extents are released to the system for future use.


What is a data segment? Each non-clustered table has a data segment. All of the table’s data is stored in the extents of its data segment. Each cluster has a data segment. The data of every table in the cluster is stored in the cluster’s data segment.


What are synonyms used for? Mask the real name and owner of an object.Provide public access to an objectProvide location transparency for tables, views or program units of a remote database.Simplify the SQL statements for database users.


What is SYSTEM tablespace and when is it created?

Every Oracle database contains a tablespace named SYSTEM, which is automatically created when the database is created. The SYSTEM tablespace always contains the data dictionary tables for the entire database.


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Top 6 tips for job interview


Tip 1: Do your homeworkYou'll likely be asked difficult questions during the interview. Preparing the list of likely questions in advance will help you easily transition from question to question.

Spend time researching the company. Look at its site to understand its mission statement, product offerings, and management team. A few hours spent researching before your interview can impress the hiring manager greatly. Read the company's annual report (often posted on the site), review the employee's LinkedIn profiles, and search the company on Google News, to see if they've been mentioned in the media lately. The more you know about a company, the more you'll know how you'll fit in to it.

Ref material: 4career.net/job-interview-checklist-40-points


Tip 2: First impressionsWhen meeting someone for the first time, we instantaneously make our minds about various aspects of their personality.Prepare and plan that first impression long before you walk in the door. Continue that excellent impression in the days following, and that job could be yours.Therefore:

Never arrive late. Use positive body language and turn on your

charm right from the start. Switch off your mobile before you step into the

room. Look fabulous; dress sharp and make sure you look

your best. Start the interview with a handshake; give a nice

firm press and then some up and down movement. Determine to establish a rapport with the

interviewer right from the start. Always let the interviewer finish speaking before

giving your response. Express yourself fluently with clarity and

precision.

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good-first-impression-at-a-job-interview

Tip 3: The “Hidden” Job MarketMany of us don’t recognize that hidden job market is a huge one and accounts for 2/3 of total job demand from enterprises. This means that if you know how to exploit a hidden job market, you can increase your chance of getting the job up to 300%.

In this section, the author shares his experience and useful tips to exploit hidden job market.

Here are some sources to get penetrating into a hidden job market: Friends; Family; Ex-coworkers; Referral; HR communities; Field communities; Social networks such as Facebook, Twitter…; Last recruitment ads from recruiters; HR emails of potential recruiters…


Tip 4: Do-It-Yourself Interviewing PracticeThere are a number of ways to prepare for an interview at home without the help of a professional career counselor or coach or a fee-based service.

You can practice interviews all by yourself or recruit friends and family to assist you.

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Tip 5: Ask questionsDo not leave the interview without ensuring that you know all that you want to know about the position. Once the interview is over, your chance to have important questions answered has ended. Asking questions also can show that you are interested in the job. Be specific with your questions. Ask about the company and the industry. Avoid asking personal questions of the interviewer and avoid asking questions pertaining to politics, religion and the like.

Ref material: 4career.net/25-questions-to-ask-employers-during-your-job-interview


Tip 6: Follow up and send a thank-you noteFollowing up after an interview can help you make a lasting impression and set you apart from the crowd.Philip Farina, CPP, a security career expert at Manta Security Management Recruiters, says: "Send both an email as well as a hard-copy thank-you note, expressing excitement, qualifications and further interest in the position. Invite the hiring manager to contact you for additional information. This is also an excellent time to send a strategic follow-up letter of interest."

Ref material: 4career.net/top-8-interview-thank-you-letter-samples


top dba interview questions and answers job interview tips

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