SQL Server architecture - August 29, 2008 at 18:00 PM by Amit
Satpute
What is RAID and what are different types of RAID configurations?
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
What are Page Splits?
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.
SQL Server architecture - Nov 18, 2008 at 18:00 PM by Rajmeet Ghai
Describe in brief 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.
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.
What are the database objects? Explain them in brief.
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.
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
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.
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