10 Oracle DBA interview questions you should know

What are the components of the physical database structure of Oracle database?

Three fundamental types of physical files make up an Oracle database:

What are the components of the logical database structure of Oracle database?

The logical structure of Oracle database consists of tablespaces and schema objects.

What is a tablespace?

An Oracle database consists of one or more logical storage units called tablespaces, which collectively store all of the database’s data.

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.

Can objects of the same schema reside in different tablespaces?

Yes.

What are the details stored in a control file?

An Oracle control file contains

  1. The database name
  2. The timestamp of database creation
  3. The names and locations of associated datafiles and redo log files
  4. Tablespace information
  5. Datafile offline ranges
  6. The log history
  7. Archived log information
  8. Backup set and backup piece information
  9. Backup datafile and redo log information
  10. Datafile copy information
  11. The current log sequence number
  12. Checkpoint information

What is an Extent?

An Extent is a specific number of contiguous data blocks, obtained in a single allocation, and
used to store a specific type of information. 

Define Transaction?

A Transaction is a logical unit of work that comprises one or more SQL statements executed
by a single user.

What happens when you open a database in nomount state?

Startup nomount includes the following tasks.

  1.    Read the spfileSID.ora or spfile.ora or initSID.ora.
  2.    Allocate the SGA.
  3.    Startup the background processes.
  4.    Open a log file named alert_SID.log and any trace files specified in the initialization parameter file.

What happens when you issue shut immediate?

Shut immediate can cause client computers to lose work.

  1. No new connections are allowed.
  2. Connected clients are disconnected and SQL statements in a process are not completed.
  3. Oracle rolls back active transactions.
  4. Oracle closes/dismounts the database.

Also read, Complete Oracle 11g Course – Step by Step Oracle 11g

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