Introduction to Mysql

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  • Topic: SQL, Database, Data Definition Language
  • Pages : 7 (1286 words )
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  • Published : June 12, 2012
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MySQL is an open source Relational Database
Management System based on the Structured
Query Language (SQL). It is very fast reliable
and flexible Database Management System
based on relation model that is developed to
manage large volumes of data at very high
speed with security. MySQL can be used for
verity of applications but it is one of the most
popular RDBMS used for the web applications
on the Internet.
It is referred as open source because it can be
run on different platform such as Unix, Linux,
Windows, OS/2, and etc. It is possible for
anyone to use and modify the software. If you
wish, you may study the source code and
change it to suit your needs.
MySQL is based on a client/server model; its
database package includes MySQL server and
MySQL client program. It supports all
functionalities of a DBMS, such as standard data
types; multi-line commands and ensures that
transactions are complete within the ACID rules.
MySQL Features
• MySQL are very fast and much reliable
for any type of application.
• It is very Lightweight Database
• Its command line tool is very powerful
and can be used to run SQL queries
against database.
• It Supports indexing and binary objects.
• It allows DBA to change the structure of
table while server is running.
• It is a very fast multithreaded-based
memory allocation system.
• MySQL is available as a separate
program for use in a client/server
network environment.
• The MySQL available for the most of all
operating system platforms.
• Programming libraries for C, Python,
PHP, Java, Delphi etc. are available to
connect to MySQL database.
MySQL 5 Features:
In traditional version of MySQL, there are some
drawbacks that, it doesn’t support Procedures
and Functions as well as Triggers. Now these
features are included in the new version of
MySQL that is MySQL 5.0. Its features are:
Views is a virtual table, which acts as a table,
but it contains no data. Views are created using
columns from one or more tables.
2. Stored Procedures and Functions
MySQL 5.0 now support Stored Procedures
and Functions. This allows you to embed
business logic at database level.
3. Triggers
The Triggers is another very imported feature
available with MySQL 5.0. Now we can add
some business logic whenever data is
inserted, Deleted or updated in the table.
High Level Conceptual Architecture of MySQL
At the highest level of abstraction MySQL
consists of five major sub-systems.

Query Engine
The Query Engine receives all the SQL
commands from the user. Its sub-system
consists of a Parser, Optimizer and Executor.
The parser checks the syntax of SQL
commands, checks the existence of requested
tables and columns, and checks user privileges
to perform the operation.
An optimizer checks the existence of indexes
to satisfy the query chooses among several
alternate ways to execute the command and
prepares an best possible plan of execution.
The executor takes the actions required to
execute the plan or requests.
Buffer Manager
The Buffer Manager lies in between the query
engine and storage manager. This sub-system
is responsible for memory management. It keeps
the active part of the data from the data files in
main memory and performs the necessary
replacement of data to and from the storage
manager, and supplies the requested data to
the query engine. Its sub-system consists of a
data buffer for table and index file, a metadata
buffer for data dictionary files and redo buffer
for the log files. In addition the buffer manager
also contains one more component the undo
buffer that keeps copies of data currently being
modified by active transactions.
Storage Manager
The Storage Manager is the backend of the
system. It manages different categories of data
files in the file system. This system deals with
efficient storage and retrieval of data to and
from the OS file systems. Its sub-system
consists of the data...
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