DBMS System Architecture | DBMS

System Architecture

DBMS is a software that handles all access to the database and each of its activities revolves around the database, whatever happens in the database can be seen as follows

 The user send a request to access database.

1. DBMS analyses the request with reference to the user who is making it i.e DBMS ensure that the particular user is allowed to make such request or not.
2. DBMS than if satisfied analyses the request with the various integrity and security constraints.
3. DBMS execute the request by going to various level of data storage.
4. DBMS if find any error while execution or request make the database subject and ask the recovery manager to recover the database in the lastly recorded consistent state.
5. If every thing goes fine , DBMS perform DBMS perform necessary operation as per the request.
   

 

Functional Components

Native User

Native user are those user who can only operate computer.It can use only those interface which is already created.For that user it is not necessary for knowing how and where data are stored.

Application User

Those user who know at least one programming language.We can change the structure of data by the help of programming language.Application programmer use application program to interact with database.

Sophisticated User

Sophisticated user are those user who use SQL to directly interact with database. This category include specialized person like engineer and scientist

DBA (Database Administrator)

One of the main reason of using DBMS rather than traditional file processing system, is to have central control of both the data and the program that access those data. The person has such a central control over the system is called database administration.In addition to the management skill. DBA must have technical skill to deal with the database.

Function of DBA

• Defining Physical Scheme: It is the job of DBA to look after the way the data is going to be stored in the database. It is called physical database design DBA uses internal DDL for this design and various mapping in the physical schema.
• Design the Conceptual Schema: This is also the job of DBA to decide what data are to be stored in database. It is he who decide what are the entities that must be recorded and with what attribute.This is done using DDL commands.
• Define integrity and security constraints: DBA enforces various object level as well as attribute levels, constraints to maintain the integrity of the database. DBA provide every user with unique password for system security.
• Internal Marketing: It is the business of DBA to ensure every user that the database contain every useful data they want , in the format.
• Managing Data Dictionary: Data dictionary contains mata-data that describe the data and data processing unit. It is useful tool for database administration and is used throughout the database system life cycle.
• Monitoring DBMS Performance: It is DBA who is responsible for designing DBMS in such a manner that is best for organization.
• Selection of H/W and S/W: DBA is the only one who decides. What are the hardware and software requirement of system.Selection is done keeping in mind the financial condition of the firm.
• Data backup and Recovery: DBA must ensure that DBMS is facilitated with various backup procedure and recovery scheme. This must be ensure that if due to any error database fails the data could be easily recovered and the system will be reformed in consistent state with minimal loss of data.

DBMS must provide data dictionary function.The data dictionary contain Mata data i.e data about data i.e definition of object of the database.It does not contain raw data at all.
It include all the various constraints mapping and schemata definition.A comprehensive dictionary will also include various additional information.

Transaction Management

Transaction management is responsible to perform ACID property

• A - Atomicity
• C - Consistency (All changes are logical correct)
• I - Isolation (At one time one transaction will run)
• D - Durability (All changes are done are persist)

DDL Compiler

It process schema definition specified in DDL and store description of the schemas in catalog. Catalog includes information such as names of files, data items, storage details of each file,mapping between schemas and constraints.

 

DML Pre-compiler

Its function is to convert the DML request into necessary form in the front end language such as (dotnet,java,C# etc) before the compilation of application program in the from end language.

Query Evaluation Engine

It handles high level queries which are entered by user.It parse, analyses and compiles or interprets the query by creating database access code and then engine call to run time processor for executing the code.

Buffer Manager

 

We know in database buffer is any temporary storage area in main memory.Buffer manager is responsible for managing space for work done by user.If buffer is not empty then it will allocate space by removing some old data and free some block for new data.

Transaction Manager

It manage and control the execution of transaction.The area of transaction is considered from Begin trans and End trans.It is managed by Commit and rollback.

File Manager

It deal with disk management i.e space allocation on the disk and low-level data structure used to store data over the disk.

Indices

These are mechanism through which DBMS optimize its performance.

Data Files

These are actual files that store the data in the database.

Statistical Data

Statistical data means analytical data which is achieved by some mathematical terms such as aggregate functions in queries(SUM, COUNT, AVG, MIN, MAX, etc)

API (Application Programming Interface)

API provide service and libraries to other application for better database interaction.