SQL Server Architecture Interview Preparation Guide

What are database files and file groups?
What are page splits?
Where does SQL server store data?
What are Collation?

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

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

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

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

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

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

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

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.

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.