Frequently asked basic and advanced Oracle Database Interview Questions and Answers on Database theory and SQL Queries with Examples for Freshers and Experienced DBA, Java, PHP, .Net Developers.
Oracle Database is a relational database management system (RDBMS) which is used to store and retrieve the large amounts of data. Oracle Database had physical and logical structures. Logical structures and physical structures are separated from each other
A user account and its associated data including tables, views, indexes, clusters, sequences,procedures, functions, triggers,packages and database links is known as Oracle schema. System, SCOTT etc are default schema's. We can create a new Schema/User. But we can't drop default database schema's.
Oracle use Tablespace for logical data Storage. Physically, data will get stored in Datafiles. Datafiles will be connected to tablespace. A tablespace can have multiple datafiles. A tablespace can have objects from different schema's and a schema can have multiple tablespace's. Database creates "SYSTEM tablespace" by default during database creation. It contains read only data dictionary tables which contains the information about the database.
Also Read Basic to Advanced Oracle SQL Query Interview Question and Answers
Control file is a binary file which stores Database name, associated data files, redo files, DB creation time and current log sequence number. Without control file database cannot be started and can hamper data recovery.
Data Blocks are the base unit of logical database space. Each data block represents a specific number of bytes of database space on a disk
6) What is an Extent ?
Extent is a collection of Continuous data blocks, which is used for storing a specific type of information.
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7) What is a Segment ?
A segment is a collection of extends which is used for storing a specific data structure and resides in the same tablespace.
8) What is Rollback Segment ?
Database contain one or more Rollback Segments to roll back transactions and data recovery.
Data Segment(for storing User Data), Index Segment (for storing index), Rollback Segment and Temporary Segment.