SQL Server Architect Interview Questions & Answers

Question 1. What Is Raid And What Are Different Types Of Raid Configurations?

Answer :

RAID stands for Redundant Array of Independent Disks. RAID defines data storage schemes to divide and replicate data among various disks so that data reliability and I/O performance can be increased.

The basic configurations of RAID are:

• LEVEL 0: Striped set without parity/Non-Redundant Array.
• LEVEL 1: Mirrored set without parity.
• LEVEL 2: Redundancy through hamming code.
• LEVEL 3: Striped set with dedicated parity/Bit interleaved parity.
• LEVEL 4: Block level parity.
• LEVEL 5: Striped set with distributed parity.
• LEVEL 6: Striped set with dual distributed Parity.

Question 2. What Is Database Architecture?

Answer :

Database architecture describes the design of the database. It explains how the data is stored. The data of the server is stored in databases. This database is further split into one or more discs. The database can be considered to have two layers. Physical layer, which is a transparent layer for the database administrators to work on. Other users typically work on the user view layer. Tables, views, procedures forms this view.

Question 3. What Are Pages And Extents?

Answer :

A page is a unit of data storage in SQL. The size of a page is 8Kb. A page has a header and a body. Different types of pages are: Date, text, index , page free space etc. The data rows are put on the page serially after the header.

Extents are units in which space is allocated to tables and indexes. An extent is 8 continuous pages. SQL Server has two types of extents: uniform and mixed extent. For efficient allocation, the SQL server does not allocate whole extents to tables with small amounts of data.

Question 4. What Do You Know About System Database?

Answer :

The system database contains information/metadata for all database present on an SQL Server instance. The system database stores information regarding logins, configuration settings, connected servers etc. It also holds various extended stored procedures to access external processes and applications.

Major system databases:

• Master: Core system database to mange Sql Server instance.
• Resource: Responsible for physically storing all system objects.
• TempDB: This is a temporary database used to store temporary, tables, cursors, indexes, variables etc.
• Model: This acts as a template database for all user created databases.
• MSDB: Database to manage SQL Server agent configurations.
• Distribution: Database primarily used for SQL Server replication.
• Report Server: Main database for reporting services to store metadata and other object definitions.
• ReportServerTempDB: Acts as a temporary storage for reporting services.

Question 5. What Are Page Splits?

Answer :

When there is not enough room on a page for a new row, a Server splits the page, allocates a new page, and moves some rows to the new page.

Question 6. Explain What Are The Database Objects?

Answer :

Database objects such as tables, primary key, and foreign key describe the structure of the content of a database. These objects also represent the properties of a server. Server side objects are objects that reside on the server but not in the database. Typical examples of server side objects include, logins, user defined error messages etc. The database objects are contained in the database project while the server objects are contained in the server project. These objects are defined in a .sql file. Most of these objects are defined in a separate file depending on the scenario. E.g it is necessary to specify columns in the same file where the table is defined.

Question 7. Illustrate Physical Database Architecture In Brief?

Answer :

The physical database architecture describes how the database and files are organized in a SQL server.

Pages and extents: these describe how the data is stored.

Physical Database Files and File groups:- describes the operating system files used to store data and logs.

Space Allocation and Reuse:- Describes the algorithms used for space allocation.

Table and Index Architecture:- Describes the way pages for tables can be indexed.

Question 8. What Is Model Database?

Answer :

It is a template database used in the creation of new database.

Question 9. Explain Logical Database Components?

Answer :

The logical components are usually used to connect to the database. Any object that a user can use to access or connect to the database is a logical component. Triggers, tables, procedures, views, keys etc are typical examples.

Question 10. What Is Temp Db Database?

Answer :

It stores temporary objects like temporary tables and temporary stored procedure.

Question 11. What Is The Difference Between Cube Operator And Roll Up Operator?

Answer :

• CUBE generates a result set that represents aggregates for all combinations of values in the selected columns.
• ROLLUP generates a result set that represents aggregates for a hierarchy of values in the selected columns.

Question 12. What Is Msdb Database?

Answer :

It stores information related to database backups, DTS packages, Replication, SQL Agent information, SQL Server jobs.

Question 13. Do You Know What The Restrictions Applicable While Creating Views Are?

Answer :

• Views can be created referencing tables and views only in the current database.
• A view name must not be the same as any table owned by that user.
• You can build views on other views and on procedures that reference views.
• Rules or DEFAULT definitions can't be associated with views.
• Only INSTEAD OF triggers can be associated with views.
• The query that defines the view cannot include the ORDER BY, COMPUTE, or COMPUTE BY clauses or the INTO keyword.
• You cannot define full-text index definitions for views.
• You cannot create temporary views.
• You cannot create views on temporary tables.

Question 14. What Is Master Database?

Answer :

Master database is system database. It contains information about server’s configuration. It is a very important database and important to backup Master database. Without Master database, server can't be started.

Question 15. Explain What Are The Restrictions That Views Have To Follow?

Answer :

Since a view is a virtual table – Columns of the view cannot be renamed. To change anything in the view, the view must be dropped and create again.

• The select statement on the view cannot contain ORDER BY or INTO TEMP.
• When a table or view is dropped, any views in the same database are also dropped.
• It is not possible to create an index on a view.
• It is not possible to use DELETE to update a view that is defined as a join.

Question 16. Explain The Microsoft Sql Server Delete Command?

Answer :

• Delete command removes records one at a time and logs into the transaction log.
• It can be used with or without where clause.
• The records can be rolled back.
• It activates trigger.
• It doesn’t reset the identity of the column.

Question 17. Explain The Truncate Command?

Answer :

• Truncate command is used to remove all rows of the column.
• The removed records are not recorded in the transaction log.
• It is the fast way to remove all the records from the table.
• The records once removed can’t be rolled back.
• It can’t activate trigger.
• It resets the identity of the column.