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.
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.
It is a template database used in the creation of new database.
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:
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 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:
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.
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.
It stores information related to database backups, DTS packages, Replication, SQL Agent information, SQL Server jobs.
It stores temporary objects like temporary tables and temporary stored procedure.
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.
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.