Database System Architecture Work

Database System Architecture work

AU: May-12,13,14,16,17, Dec.- 08,15,17,19, Marks 16

• The typical structure of typical DBMS is based on relational data model as shown in Fig 1.5.1.

• Consider the top part of Fig. 1.5.1. It shows application interfaces used by naïve users, application programs created by application programmers, query tools used by sophisticated users and administration tools used by database administrator.

• The lowest part of the architecture is for disk storage.

• The two important components of database architecture are - Query processor and storage manager.

Query processor:

• The interactive query processor helps the database system to simplify and facilitate access to data. It consists of DDL interpreter, DML compiler and query evaluation engine.

• With the following components of query processor, various functionalities are performed -

i) DDL interpreter: This is basically a translator which interprets the DDL statements in data dictionaries.

ii) DML compiler: It translates DML statements query language into an evaluation plan. This plan consists of the instructions which query evaluation engine understands.

iii) Query evaluation engine: It executes the low-level instructions generated by the DML compiler.

• When a user issues a query, the parsed query is presented to a query optimizer, which uses information about how the data is stored to produce an efficient execution plan for evaluating the query. An execution plan is a blueprint for evaluating a query. It is evaluated by query evaluation engine.

Storage manager:

• Storage manager is the component of database system that provides interface between the low level data stored in the database and the application programs and queries submitted to the system.

• The storage manager is responsible for storing, retrieving, and updating datain the database. The storage manager components include -

i) Authorization and integrity manager: Validates the users who want to access the data and tests for integrity constraints.

ii) Transaction manager: Ensures that the database remains in consistent despite of system failures and concurrent transaction execution proceeds without conflicting.

iii) File manager: Manages allocation of space on disk storage and representation of the information on disk.

iv) Buffer manager: Manages the fetching of data from disk storage into main memory. The buffer manager also decides what data to cache in main memory. Buffer manager is a crucial part of database system.

• Storage manager implements several data structures such as -

i) Data files: Used for storing database itself.

ii) Data dictionary: Used for storing metadata, particularly schema of database.

iii) Indices: Indices are used to provide fast access to data items present in the database

Review Questions

1. Explain the overall architecture of database system in detail.    AU: May-14,17, Dec.-17, Marks 8, May-16, Marks 16

2. With the help of a neat block diagram explain basic architecture of a database management system.   AU May-12, May-13, Marks 16, Dec-15, Marks 8

3. Explain component modules of a DBMS and their interactions with the architecture   AU: Dec.-08, Marks 10

4. Sketch the typical component modules of DBMS. Indicate and explain interactions between those modules of the system. AU: Dec.-19, Marks 7