DBMS Notes
HubUnit 1 — Introduction to DBMS & Entity-Relationship ModelAdvantages and Disadvantages of DBMSAggregation — Database Management SystemsCharacteristics of DBMSData IndependenceData ModelsDatabase Users and AdministratorsDBMS LanguagesER DiagramsEntity-Relationship (ER) ModelIntroduction to DBMSKeys in DBMSRelationships and CardinalitySchema and InstanceSpecialization and GeneralizationDBMS Unit 1 Summary - Database FundamentalsThree-Level Architecture (ANSI/SPARC Architecture)Weak Entity SetUnit 2 — Relational Model & SQLConstraints in SQLCursorsDCL and TCL CommandsDDL CommandsDML CommandsDomain Relational Calculus (DRC) - Complete TutorialFunctions and Stored ProceduresJoins in SQLNested Queries (Subqueries)Relational AlgebraRelational Calculus in Database Management SystemsRelational ModelSQL IntroductionDBMS Unit 2 Summary - SQL and Relational ModelTriggers in SQL — Database Management SystemsTuple Relational Calculus (TRC)Views in SQL — Database Management SystemsArmstrong\Boyce-Codd Normal Form (BCNF) — Database Management SystemsClosure of AttributesDependency PreservationFifth Normal Form (5NF)First Normal Form (1NF) - Database NormalizationFourth Normal Form (4NF)Functional DependencyLossless DecompositionMultivalued DependencyNormal Forms — OverviewNormalization — IntroductionSecond Normal Form (2NF) — Database Management SystemsUnit 3 Summary — NormalizationThird Normal Form (3NF) — Database Management SystemsUnit 4 — Transaction Management & Concurrency ControlACID PropertiesCheckpointsConcurrency Control & SerializabilityDeadlock in DBMSLock-Based Protocols & Two-Phase LockingLog-Based RecoveryRecovery SystemSerializabilityShadow PagingUnit 4 Summary — Transaction Management & Concurrency ControlTimestamp-Based ProtocolTransaction ManagementTransaction StatesTwo-Phase Locking (2PL)Unit 5 — Storage & IndexingB+ TreeB-TreeCost EstimationDynamic HashingFile OrganizationHashing TechniquesIndexing — IntroductionMulti-Level IndexingQuery Optimization — Database Management SystemsQuery ProcessingSingle-Level IndexingStatic HashingUnit 5 Summary — Storage & IndexingUnit 6 — Advanced Topics in DBMSCloud DatabaseData MiningData WarehouseDatabase SecurityDistributed DatabaseDistributed Query ProcessingDistributed DBMS Architecture, Fragmentation & ReplicationMongoDB — IntroductionNoSQL DatabaseReplication in Distributed DatabasesUnit 6 Summary — Advanced Topics in DBMSViva Voce — DBMSImportant Viva Questions — DBMSInterview Questions — DBMSViva Answers — DBMSDBMS Multiple Choice Questions (MCQs)DBMS Lab Programs
A cloud database is a database service built, deployed, and accessed through a cloud computing platform. It provides database capabilities as a service...
What is a Cloud Database?
A cloud database is a database service built, deployed, and accessed through a cloud computing platform. It provides database capabilities as a service (DBaaS — Database as a Service) over the internet, managed by a cloud provider.
Users pay for what they use, scale on demand, and the provider handles infrastructure, patching, backups, and availability.
Major Cloud Database Services
| │ RDS | Managed relational (MySQL, Postgres) │ |
| │ DynamoDB | Managed NoSQL (key-value + document) │ |
| │ Redshift | Managed data warehouse │ |
| │ Aurora | MySQL/PostgreSQL-compatible, cloud- │ |
| │ ElastiCache | Managed Redis/Memcached (caching) │ |
| │ Neptune | Managed graph database │ |
| │ Azure SQL Database | Managed SQL Server │ |
| │ Azure Cosmos DB | Multi-model NoSQL (global) │ |
| │ Azure Synapse | Analytics + data warehouse │ |
| │ Cloud SQL | Managed MySQL/PostgreSQL │ |
| │ BigQuery | Serverless data warehouse │ |
| │ Firestore | NoSQL document database │ |
| │ Cloud Spanner | Globally distributed RDBMS │ |
Advantages of Cloud Databases
| 1. No hardware purchase | Pay-as-you-go; CAPEX → OPEX |
| 2. Automatic scaling | Scale up/down in minutes |
| 3. High availability | Multi-AZ deployments; 99.99% SLA |
| 4. Managed backups | Automated daily backups; PITR |
| 5. Auto-patching | No manual DB software updates |
| 6. Global distribution | Deploy in 25+ regions worldwide |
| 7. Fast deployment | New DB instance ready in minutes |
| 8. Built-in monitoring | Metrics, alerts, performance insights |
| 9. Security built-in | Encryption at rest and in transit |
| 10. Disaster recovery | Cross-region replication available |
Disadvantages of Cloud Databases
| 1. Cost at scale | Can become expensive for large workloads |
| 2. Vendor lock-in | Migrating from AWS Aurora to Azure = complex |
| 3. Network latency | Extra round-trip vs on-premise co-located DB |
| 4. Limited control | Cannot access underlying OS/hardware |
| 5. Data sovereignty | Regulations may restrict data location |
| 6. Internet dependency | Outage if network fails |
Cloud Database Architecture Concepts
Multi-AZ (High Availability)
| AZ-1 (Mumbai) | AZ-2 (Hyderabad) | |||
|---|---|---|---|---|
| PRIMARY DB | ───► | STANDBY DB | ||
| (writes) | sync | (auto-failover) |
Read Replicas (Scaling Reads)
┌─────────────────────────────────────────────┐
│ │
│ Primary DB ──async replication──► Read │
│ (handles writes) Replica 1│
│ ──async──────► Read │
│ Replica 2│
│ ──async──────► Read │
│ Replica 3│
└─────────────────────────────────────────────┘
App servers send writes to Primary, reads to Replicas
→ Distributes read load across multiple replicas
Serverless Databases
| Traditional | Pay for provisioned instances (24/7) |
| Serverless | Pay only when queries are running |
| Amazon Aurora Serverless v2 | auto-scales to 0 when idle |
| Google BigQuery | pay per query, no provisioning |
| PlanetScale | MySQL-compatible, serverless |
| Best for | Dev/test environments, variable workloads, |
Cloud Database Security
Encryption
- At Rest: AES-256 encryption of stored data (default on most services)
- In Transit: TLS/SSL for all connections
Network Isolation
- VPC (Virtual Private Cloud): DB in private subnet, not public internet
- Security Groups: Firewall rules on which IPs/ports can connect
Access Control
- IAM (Identity and Access Management): cloud-level permissions
- DB-level users/roles: GRANT/REVOKE as usual
Audit Logging
- All queries logged for compliance (CloudTrail on AWS)
Continue the lesson path
Study next in this module
01Unit 6Data MiningData Mining is the process of discovering interesting, previously unknown patterns, correlations, anomalies, and insights from large amounts of data stored...02Unit 6Data WarehouseA Data Warehouse (DW) is a large, centralized repository of integrated data from multiple sources, optimized for analytical querying and business...03Unit 6Database SecurityDatabase security refers to the collective measures used to protect and secure a database from unauthorized access, misuse, corruption, or theft of data. It...04Unit 6Distributed DatabaseA distributed database is a collection of multiple, logically interrelated databases spread across a computer network. The data is physically stored at...