March 15, 2018

Sreekanth B

Dell Oracle Experienced Freshers Interview Questions Answers

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.

Explain The Function Of Optimizer In Oracle?

The optimizer determines the most efficient way to execute a SQL statement based on the kind of data in the table and the statements fired to fetch that data like indexes, full table scans, loops, joins etc. Optimizers are also used to avoid excessive I/O resources.

What Is The Use Of Aggregate Functions In Oracle?

Aggregate function is a function where values of multiple rows or records are joined together to get a single value output.

Common aggregate functions are :

Average
Count
Sum

What Are The Components Of Physical Database Structure Of Oracle Database?

Components of physical database structure are given below:

One or more data files.
Two or more redo log files.
One or more control files.

What Is Hash Cluster?

Hash Cluster is a technique used for storing the table to make it faster to retrieve. It order to retrieve the rows from the table, apply the hash value on the table.

What Is Hot Backup And How It Can Be Taken?

Hot backup is taking backup of archived log files when database is open.THe ARCHIVE LOG switch should be enabled for this to happen. Hot backup happens while the database is still being accessed by users and tables are being updated. It does not need the database to have a downtime.

What Is Using Clause And Give Example?

he USING clause is used to specify with the column to test for equality when two tables are joined.

[sql]Select * from table1 join table2 using table1 ID[/sql]

table1 tables join with the table2 tables with the tableID.

What Is The Purpose Of Save Points In Oracle Database?

Save Points are used to divide a transaction into smaller phases.
It enables rolling back part of a transaction.
Maximum 5 save points are allowed in Oracle Database.
Whenever an error is encountered, it is possible to rollback from the point where the SAVEPOINT has been saved.

What Is A System Tablespace And When It Is Created?

When the database is created in Oracle database system, it automatically generate a SYSTEM named SYSTEM tablespace. The SYSTEM tablespace contains data dictionary tables for the entire database.

What Is The Fastest Query Method To Fetch Data From The Table?

You can use ROWID to fetch Row from the table. The use of ROW ID is the fastest query method for fetching data from the table.

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