Oracle Admin Interview Questions and Answers - 1

Question: 1

What is the logical structure of the disk resource?

Following is the logical structure of the disk resources:

• Data block – Refers to the smallest logical storage unit. Size of a data block is a multiple of operating system block size.
• Extent – Refers to the contiguous set of data blocks, which is allocated as a unit to a segment.
• Tablespace – Refers to the final logical storage unit. It is mapped to physical data file.
• Segment – Allocates a logical structure, such as table. It is a set of extents, which are stored in the same tablespace.

Question: 2

What is LoGWRiter(LGWR)?

LGWR is the background process that writes redo information from redo log buffers to the log files.

Question: 3

What is the difference between multithreaded/shared server and dedicated server?

• In case of a dedicated server, a server process is associated with a single user process and serves it dedicatedly.
• In case of a shared server, a single server process can serve multiple user processes. This is achieved with the help of a dispatcher process, which places each process in a single request queue.
• Server process picks up the user process whenever it is free. After that, the server process puts the result in the individual response queue associated with different dispatcher processes.

Question: 4

How long does the rollback segment hold data to maintain consistency?

• Rollback segment holds the previous version of data block until either its gets committed or the space is not available for reuse.
• If a session is reading specific block from rollback segment while the other session has committed the information, then more rollback space is required to maintain more rollback information.
• In that case, this specific block ages out of the rollback segment and the reading or selecting session gets an error.

Question: 5

What background process refreshes materialized views?

The job queue processes refresh the materialized views.