How unit 5 is examined
The unit covers DBMS (architecture, data independence, DBA, DDL/DML, data dictionary, transactions) and cloud computing (infrastructure, service and deployment models, pros and cons); both topics carry high marks.
Data base Management System: Introduction, File oriented approach and Database approach, Data Models, Architecture of Database System, Data independence, Data dictionary, DBA, Primary Key, Data definition language and Manipulation Languages
High weight
Definition. A DBMS is software that lets users define, create, store, retrieve, update and control a shared, organised collection of related data (the database) while keeping it consistent and secure.
File approach vs database approach.
| Point | File-oriented | Database (DBMS) |
|---|---|---|
| Redundancy | Same data repeated in many files | Controlled, data stored once |
| Consistency | Copies disagree | One copy, consistent |
| Program-data link | Data format inside programs | Data independence |
| Sharing and security | Poor | Multi-user, access control |
| Backup and recovery | Manual | Built in |
Data models. A data model describes structure and relationships: hierarchical (tree), network (graph of records), relational (tables of rows and columns, most widely used) and object-oriented.
Diagram.
Key points.
- The external (view) level shows each user only the part of the database relevant to them, hiding the rest.
- The conceptual (logical) level describes the whole database: entities, attributes, relationships and constraints, independent of storage.
- The internal (physical) level describes how data is stored: files, indexes, record layout and access paths.
- Physical data independence means the internal schema can change (new index, new file organisation) without changing the conceptual schema.
- Logical data independence means the conceptual schema can change (add a field or table) without changing external views or programs; it is harder to achieve.
- Functionally, the query processor (DDL interpreter, DML compiler, query evaluation engine) works with the storage manager (buffer, file, authorization and transaction managers) over the data files and data dictionary.
- The data dictionary is a central repository of metadata: table and column names, data types, keys, constraints, users and privileges. Example: EMP(ID int primary key, Name varchar(30)) is recorded as entries in it.
- The primary key is a minimal attribute set that uniquely identifies each row and cannot be NULL (for example, RollNo).
- DBA functions: schema definition, storage structure, user authentication and access rights (security), integrity constraints, backup and recovery, and performance tuning through indexing and query optimisation.
- A transaction is a logical unit of work executed as one indivisible task; COMMIT saves it and ROLLBACK undoes it after failure, which prevents inconsistent states. ACID: Atomicity (all or nothing), Consistency (valid state to valid state), Isolation (concurrent transactions do not interfere), Durability (committed data survives crashes).
DDL and DML.
| DDL (defines structure) | DML (handles data) | |
|---|---|---|
| Commands | CREATE, ALTER, DROP, TRUNCATE | SELECT, INSERT, UPDATE, DELETE |
| Example | CREATE TABLE Emp(Id INT PRIMARY KEY, Name VARCHAR(30)); |
INSERT INTO Emp VALUES(1,'Ravi'); |
| More | ALTER TABLE Emp ADD Salary INT; DROP TABLE Emp; |
UPDATE Emp SET Salary=500 WHERE Id=1; DELETE FROM Emp WHERE Id=1; SELECT * FROM Emp; |
DML is procedural (user says what and how) or non-procedural (only what, as in SQL).
Answer frame. Architecture: open with the three-level definition; draw the diagram; develop points 1-5 then 6; close with data independence. DDL/DML: define both, give the table with one example each. DBA: list functions under performance, integrity, security. Transaction: define, then ACID, then commit and rollback.
Pitfall: Do not confuse physical independence (storage changes) with logical independence (schema changes).
Asked: [7 marks] (Jun 2022, Dec 2024) Draw and explain the architecture of database systems; describe the key components of a DBMS architecture. Asked: [7 marks] (Nov 2022) Explain DDL and DML commands with suitable examples. Asked: [7 marks] (Jun 2023) Describe data independence and DBA in detail. Asked: [7 marks] (Jun 2024) What is a database transaction and why is it important in maintaining data integrity? Asked: [7 marks] (Jun 2025) Describe the functions of a DBA in maintaining performance, integrity and security of a database. Asked: [14 marks] (Dec 2023) Explain with example: a) Data dictionary b) Cloud infrastructure. Asked: [14 marks] (Jun 2024) Short notes: i) DDL and DML commands ii) Remote Sensing and GIS iii) I/O Device. Asked: [14 marks] (Nov 2022) Short notes: a) Cloud Infrastructure b) DBA c) Logic Bombs. Asked: [14 marks] (Jun 2022) Short notes: a) Good computer security habits b) Data Manipulation Language c) IaaS and PaaS. Asked: [14 marks] (Dec 2024) Short notes: i) Logical operators in C++ ii) Data Independence iii) Service delivery models in cloud computing.
Cloud computing: definition, cloud infrastructure, cloud segments or service delivery models (IaaS, PaaS and SaaS), cloud deployment models/ types of cloud (public, private, community and hybrid clouds), Pros and Cons of cloud computing
High weight
Definition. Cloud computing is the on-demand delivery of computing resources (servers, storage, databases, software) over the Internet on a pay-as-you-go basis.
Diagram.
Key points.
- The Internet is the transport backbone of the cloud: users reach remote data centres through a browser or app, so the cloud cannot work without it.
- Characteristics are on-demand self-service, broad network access, resource pooling, rapid elasticity and measured service.
- Cloud infrastructure is the hardware and software that powers the cloud: physical servers, storage, network, a virtualization layer that splits hardware into virtual machines, and a management layer for provisioning and billing. Example: AWS EC2, Microsoft Azure.
- IaaS gives virtual machines, storage and networks; the user manages OS and applications (AWS EC2, Google Compute Engine).
- PaaS gives a runtime and development tools; the user manages only the application and data (Google App Engine, Heroku).
- SaaS gives ready-to-use software through a browser; the provider manages everything (Google Workspace, Office 365).
- Public cloud is shared over the Internet and cheap (AWS, Azure); private cloud serves one organisation and is more secure; community cloud is shared by organisations with common needs; hybrid cloud combines public and private.
- Pros: lower cost, scalability, anywhere access, automatic updates, disaster recovery. Cons: internet dependency and downtime, security and privacy worries, vendor lock-in, limited control.
Cloud vs traditional computing.
| Point | Traditional (on-premise) | Cloud |
|---|---|---|
| Cost | Large CapEx up front | OpEx, pay per use |
| Scalability | Buy new hardware | Elastic, instant |
| Access | Local network | Anywhere via Internet |
| Maintenance | Own staff | Provider |
| Setup time | Weeks | Minutes |
Responsibility. IaaS: user runs OS, middleware, app; PaaS: user runs app only; SaaS: user runs nothing.
Answer frame. Cloud definition: open with the definition, link to the Internet, draw the classification tree, then points 2-3, 4-6, 7. Deployment types: one line per type with example. Pros and cons: two short lists of four each. Service models: open with the three, close with the responsibility line.
Asked: [7 marks] (Jun 2022) Write down the pros and cons of cloud computing. Asked: [7 marks] (Nov 2022) Explain different types of clouds. Asked: [7 marks] (Jun 2023) What do you understand by cloud computing? Describe cloud infrastructure in detail. Asked: [7 marks] (Dec 2024) What is cloud computing and how does it differ from traditional computing models? Asked: [7 marks] (Jun 2024) Explain cloud computing and its relationship to the Internet. Asked: [7 marks] (Jun 2025) Discuss the different cloud service delivery models.
Last-minute revision
- DBMS: software to define, store, retrieve and control shared data with less redundancy.
- Three levels: external, conceptual, internal.
- Physical independence: change storage, schema stays; logical independence: change schema, views stay.
- Data dictionary stores metadata.
- Primary key: unique and not NULL.
- DDL: CREATE, ALTER, DROP, TRUNCATE; DML: SELECT, INSERT, UPDATE, DELETE.
- ACID: Atomicity, Consistency, Isolation, Durability.
- Cloud: on-demand Internet delivery, pay as you go.
- IaaS, PaaS, SaaS: EC2, App Engine, Office 365.
- Deployment: public, private, community, hybrid.
Memory hooks
- E-C-I: External, Conceptual, Internal, top to bottom.
- ACID: All-or-nothing, Correct, Isolated, Durable.
- "I-P-S": the user manages less at each step (Infrastructure, Platform, Software).
- DDL defines the table, DML fills it.
Coverage checklist
- Data base Management System: Introduction, File oriented approach and Database approach, Data Models, Architecture of Database System, Data independence, Data dictionary, DBA, Primary Key, Data definition language and Manipulation Languages: covers all DBMS questions (architecture, DDL/DML, data independence, DBA, transaction, data dictionary).
- Cloud computing: definition, cloud infrastructure, cloud segments or service delivery models (IaaS, PaaS and SaaS), cloud deployment models/ types of cloud (public, private, community and hybrid clouds), Pros and Cons of cloud computing: covers all cloud questions (pros/cons, types, infrastructure, traditional comparison, Internet, service models).