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Q:

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

Answer

Oracle database comprises of three kinds of files:
- Datafiles
- Redo log files
- Control files

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Subject: Oracle

Q:

What do you mean by a deadlock?

Answer

 - When two processes are waiting to update the rows of a table which are locked by another process, the situation is called a deadlock.
 - The reasons for it to happen are:
 * lack of proper row lock commands.
 * Poor design of front-end application
- It reduces the performance of the server severely.
- These locks get automatically released automatically when a commit/rollback operation is performed or any process is killed externally.

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Subject: Oracle

Q:

What is Control File used for?

Answer

Control File is used for:
- Database recovery.
- Whenever an instance of an ORACLE database begins, its control file is used to identify the database and redo log files that must be opened for database operation to go ahead.

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Subject: Oracle

Q:

What is a sub query? What are its various types?

Answer

- Sub Query also termed as Nested Query or Inner Query is used to get data from multiple tables.
- A sub query is added in the where clause of the main query.

There can be two types of subqueries:
a.) Correlated sub query :
- It can reference column in a table listed in the from list of the outer query but is not as independent as a query.
b.) Non-Correlated sub query :
- Results of this sub query are submitted to the main query or parent query.
- It is independent like a query

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Subject: Oracle

Q:

What are the uses of synonyms?

Answer

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

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Subject: Oracle

Q:

What is a synonym? What are its various types?

Answer

A synonym can be called as an alias for a table, view, sequence or program unit. It is basically of two types:
- Private - Only the owner can access it.
- Public - Can be accessed by any database user.

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Subject: Oracle

Q:

What do you mean by a tablespace?

Answer

- These are the Logical Storage Units into which a database is divided.
- It is used to group together the related logical structures.

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Subject: Oracle

Q:

List the various Oracle database objects.

Answer

- TABLES
- VIEWS
- INDEXES
- SYNONYMS
- SEQUENCES
- TABLESPACES

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Subject: Oracle