STRUCTURE OF DBMS

Saturday, February 23, 2008 by Ankit Goyal

STRUCTURE OF DBMS

DBMS (Database Management System) acts as an interface between the user and the database. The user requests the DBMS to perform various operations (insert, delete, update and retrieval) on the database. The components of DBMS perform these requested operations on the database and provide necessary data to the users. The various components of DBMS are shown below: -

Fig. 2.1 Structure Of DBMS

1. DDL Compiler - Data Description Language compiler processes schema definitions specified in the DDL. It includes metadata information such as the name of the files, data items, storage details of each file, mapping information and constraints etc.

2. DML Compiler and Query optimizer - The DML commands such as insert, update, delete, retrieve from the application program are sent to the DML compiler for compilation into object code for database access. The object code is then optimized in the best way to execute a query by the query optimizer and then send to the data manager.

3. Data Manager - The Data Manager is the central software component of the DBMS also knows as Database Control System.

The Main Functions Of Data Manager Are: –

• Convert operations in user's Queries coming from the application programs or combination of DML Compiler and Query optimizer which is known as Query Processor from user's logical view to physical file system.

• Controls DBMS information access that is stored on disk.

• It also controls handling buffers in main memory.

• It also enforces constraints to maintain consistency and integrity of the data.

• It also synchronizes the simultaneous operations performed by the concurrent users.

• It also controls the backup and recovery operations.

4. Data Dictionary - Data Dictionary is a repository of description of data in the database. It contains information about

• Data - names of the tables, names of attributes of each table, length of attributes, and number of rows in each table.

• Relationships between database transactions and data items referenced by them which is useful in determining which transactions are affected when certain data definitions are changed.

• Constraints on data i.e. range of values permitted.

• Detailed information on physical database design such as storage structure, access paths, files and record sizes.

• Access Authorization - is the Description of database users their responsibilities and their access rights.

• Usage statistics such as frequency of query and transactions.

Data dictionary is used to actually control the data integrity, database operation and accuracy. It may be used as a important part of the DBMS.

Importance of Data Dictionary -

Data Dictionary is necessary in the databases due to following reasons:

• It improves the control of DBA over the information system and user's understanding of use of the system.

• It helps in documentating the database design process by storing documentation of the result of every design phase and design decisions.

• It helps in searching the views on the database definitions of those views.

• It provides great assistance in producing a report of which data elements (i.e. data values) are used in all the programs.

• It promotes data independence i.e. by addition or modifications of structures in the database application program are not effected.

5. Data Files - It contains the data portion of the database.

6. Compiled DML - The DML complier converts the high level Queries into low level file access commands known as compiled DML.

7. End Users - They are already discussed in previous section.

Filed under , having  

17 comments:

aakshara said...

hey thanks i really wanted this info.

kit2 said...

Thanks a tonne dude!!! :)

Neeraj Singh said...

Thanks dear for this valuable piece of information in your blog.

prabhu said...

thanksssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssss

Subramani said...

Thanks a lot dude.

Muthu Ganapathy said...

this was very useful keep helping others.....

luv_abhi1923 said...

quite understanding n clarified figure....wid brief info of points...i liked it,,

tanya said...

thnkssssssssssssssssss dude

pavan said...

its very nice and exordinary thankssssssssssssssssssss

Ankit Goyal said...

Thanks to all for your comments :)

Basu said...

Very simplied and easy to understand Thanks a lot.

aswini said...

very nice i can clearly understand this part superb

Lakhan Meena said...

thanks dude....

Janice Rafael said...

the next time I read a blog, I hope that it doesnt disappoint me as much as this one. I mean, I know it was my choice to read, but I actually thought youd have something interesting to say. All I hear is a bunch of whining about something that you could fix if you werent too busy looking for attention.
Oracle SQL

Le Mystique said...
This comment has been removed by the author.
Le Mystique said...

Hi,
I am an SEO and internet marketing consultant.
My client's previous SEO consultant left a spammy comment with the alias Janice Rafael at your blog which links to my client's site. This is causing us serious trouble with respect to SEO and the comment does not look good on your blog either.
We apologize for the inconvenience and we request you to remove that comment as well as this current one that I am making within 48 hours. If you don't do so, I will have to use Google's disavow tool to get the spammy comment along with the website link removed and, sorry to say this, but Google may not look too nicely upon you either for not having removed the comment. Thanks in advance for your cooperation.

nk said...

Awesome dude !! love it !! in short form :)