Oracle Interview Questions
What Is Oracle?
Oracle is a company. Oracle is also a database server, which manages data in a very structured way. It allows users to store and retrieve related data in a multiuser environment so that many users can concurrently access the same data. All this is accomplished while delivering high performance. A database server also prevents unauthorized access and provides efficient solutions for failure recovery.
What Is An Oracle Database?
An Oracle database is a collection of data treated as a big unit in the database server.
What Is An Oracle Instance?
Every running Oracle database is associated with an Oracle instance. When a database is started on a database server (regardless of the type of computer), Oracle allocates a memory area called the System Global Area (SGA) and starts one or more Oracle processes. This combination of the SGA and the Oracle processes is called an Oracle instance. The memory and processes of an instance manage the associated database’s data efficiently and serve the one or multiple users of the database.
What Is Oracle Table?
A table is the basic unit of data storage in an Oracle database. The tables of a database hold all of the user accessible data. Table data is stored in rows and columns.
What Is An Oracle View?
A view is a virtual table. Every view has a query attached to it. (The query is a SELECT statement that identifies the columns and rows of the table(s) the view uses.)
What Is An Oracle Sequence?
A sequence generates a serial list of unique numbers for numerical columns of a database’s tables.
What Is An Oracle Index?
An index is an optional structure associated with a table to have direct access to rows, which can be created to increase the performance of data retrieval. Index can be created on one or more columns of a table.
What Is An Oracle Data File?
An Oracle data file is a big unit of physical storage in the OS file system. One or many Oracle data files are organized together to provide physical storage to a single Oracle tablespace.
What Are The Components Of Physical Database Structure Of Oracle Database?
Oracle database is comprised of three types of files. One or more datafiles, two are more redo log files, and one or more control files.
What Are The Components Of Logical Database Structure Of Oracle Database?
There are tablespaces and database’s schema objects.
What Is A Tablespace?
A database is divided into Logical Storage Unit called tablespaces. A tablespace is used to grouped related logical structures together.
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.
Explain The Relationship Among Database, Tablespace And Data File ?
Each databases logically divided into one or more tablespaces one or more data files are explicitly created for each tablespace.
What Is Schema?
A schema is collection of database objects of a user.
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.
Can Objects Of The Same Schema Reside In Different Tablespaces?
Yes.
Can A Tablespace Hold Objects From Different Schemes?
Yes.
What Is Partial Backup ?
A Partial Backup is any operating system backup short of a full backup, taken while the database is open or shut down.
What Is Mirrored On-line Redo Log ?
A mirrored on-line redo log consists of copies of on-line redo log files physically located on separate disks, changes made to one member of the group are made to all members.
What Is Full Backup ?
A full backup is an operating system backup of all data files, on-line redo log files and control file that constitute ORACLE database and the parameter.