Top Database Administrator Interview Questions And Answers
Last updated on Tue 17 Mar 2020
The students who are attending an interview for the position of DBA must go through below questions. It has the best collection of interview questions which are taken from many MNCs interview papers. These questions are helpful in facing the interview confidently. It is better to prepare for an interview from these questions before going for an interview.
- Define DBA?
DBA is Database Administrator and it is a common job that a database specialist is doing. In general, there are production DBAs and development DBAs. Usually, development DBA works closely along with developer’s team and gets involved in design decisions, advising on writing and performance good SQL. Databases are maintained by production DBA in an organization so it is tough and demanding job. Often, DBA gets involved in design decisions and simply keep things running. Thus, it is also a rewarding job both in terms of satisfaction and financial.
- Define a segment?
A set of extents that are allocated for specific logic structure is known as a segment.
- Define a sequence?
A serial list of unique numbers for numerical columns is generated by a sequence of tables in a database.
- Describe procedure, function and package?
A procedure and a function are same in that they are planned to be a collection of PL/SQL code that performs a single task. Procedure will not return values to calling function and a single value is returned by the function. The collection of procedures and functions that are grouped together depending on the commonality to a business application or function is known as a package.
- Define synonym?
The alias of a table, sequence, view or program unit is synonym.
- Describe ORA-01555?
This error occurs when a snapshot is old in rollback. Usually, it is solved by increasing the size of rollbacks or undo retention. Additionally, you must look the logic present in the application getting error message.
- Give the command used to encrypt PL/SQL application?
- Give three advisory statics you collect?
- Segment level statistics
- Timed statistics
- Buffer cache advice
- Describe redo logs?
Redo logs are physical and logical structures that are designed to hold changes made to database and are aided in the database recovery.
- Differentiate temporary tablespace and permanent tablespace?
Temporary objects like sort structures are used by temporary tablespace whereas permanent table spaces are used to store objects intended to use as true database objects.
- Define database schema?
A set of objects that are owned by user account is known as schema.
- Define snapshot log?
In a master database, snapshot log is a table that is related to master table. A snapshot log is used by ORACLE to track rows updated in master table. Snapshots are updated according to master table using snapshot logs.
- Define distributed database?
A network of databases that are managed by many database servers that is appeared to user as one logical database is known as a distributed database. In distributed database, data in all the databases is accessed and changed simultaneously.
- Define database clusters?
If a group of tables stored together physically and share common columns and are used together frequently is known as a cluster.
- Define an index?
Index is a database structure which is used by the server to access a row in the table directly. Automatically, an index is created if a unique primary key constraint is mentioned in create table command.
- Define database instance?
The set of memory structure and background processes that gain access on database files is a database instance. All the users share this process. Most queried data from the database is stored using memory structure. This helps in enhancing database performance by decreasing I/O performed on data file.
- Why ANALYZE command is used?
It is used to perform these functions on a table, index or cluster. It is used to collect object statistics used by the optimizer and store in data dictionary. Object statistics used by an object from a data dictionary can be deleted. Structure of an object can be validated. It identifies chained and migrated rows of cluster or table.