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Database Articles
Page 114 of 547
Number of Possible Super Keys in DBMS
A super key is a set of one or more attributes that uniquely identifies each record in a table. All primary/candidate keys are super keys, but not all super keys are candidate keys (candidate keys are minimal super keys with no redundant attributes). Key Formulas Scenario (n = total attributes) Formula One candidate key with k attributes 2(n−k) Maximum super keys (at least 1 attribute) 2n − 1 Two candidate keys (Inclusion-Exclusion) SK(A1) + SK(A2) − SK(A1 ∪ A2) Three candidate keys SK(A1) + SK(A2) + SK(A3) − ...
Read MoreNoSQL Data Architecture Patterns
NoSQL databases use different architecture patterns to organize data − key-value, document, column-family, graph, and object formats. Unlike relational databases that use tables, these patterns offer flexibility for handling diverse data types, big data, and real-time processing. Architecture Patterns Pattern Data Model Best For Examples Key-Value Key → Value pairs Caching, sessions, fast lookups Redis, Riak, DynamoDB Document JSON/BSON documents Content management, catalogs MongoDB, Couchbase Column-Family Column families with key-value pairs Big data, time-series, IoT Cassandra, HBase Graph Nodes and edges Social networks, recommendations Neo4j, OrientDB ...
Read MoreMultimedia Database Concepts
A multimedia database stores and manages different types of media − text, images, audio, video, and animations. All media files are stored as binary strings encoded according to their file types, enabling efficient storage and retrieval of rich content. Types of Multimedia Data Type Description Examples Static Media Not time-dependent Images, graphics, text Dynamic Media Time-dependent Audio, video, animations Dimensional Media 3D data for CAD programs 3D models, vector graphics Contents of a Multimedia Database Media data − The actual multimedia object (image, audio, video). ...
Read MoreNormal Forms Based on Primary Keys
Normalization organizes data in a database to reduce redundancy and improve consistency. Primary keys uniquely identify each row, and normal forms define progressive rules based on functional dependencies to eliminate data anomalies. Types of Keys Key Type Definition Super Key Set of attributes that uniquely identifies each record (may have extra attributes) Candidate Key Minimal super key − no redundant attributes Primary Key Chosen candidate key for unique identification Alternate Key Candidate keys not selected as primary key Foreign Key Column referencing another table's primary key ...
Read MoreNested Queries in SQL
A nested query (subquery) is a query placed inside another query. The inner query executes first and its result is used by the outer query for more complex data retrieval. Syntax SELECT column1, column2 FROM table1 WHERE column1 IN ( SELECT column1 FROM table2 WHERE condition ); Types of Nested Queries Non-Correlated Inner runs independently Result passed to outer Operators: IN, NOT IN, ALL, ANY ...
Read MoreMultilevel Indexes
In RDBMS, indexes are data structures that speed up data retrieval by reducing disk accesses. As databases grow, single-level indexes become too large for main memory. Multilevel indexes solve this by dividing the index into a hierarchy of smaller, manageable blocks. Index Components Search Key Sorted primary/candidate key points to Data Reference Pointer to disk ...
Read MoreMulti-tier architecture of Data Warehouse
A data warehouse is a central repository that consolidates data from multiple sources into a format optimized for analysis and decision-making. To handle the complexity and volume of data efficiently, data warehouses use a multi-tier architecture where each layer performs a specific function. Multi-tier Architecture Layers Data Sources DBs, Files, External APIs ...
Read MoreMOSS Concurrency Control Protocol (Distributed Locking in Database)
The MOSS (Multi-Object Synchronized Scheduling) Concurrency Control Protocol manages concurrency in distributed database systems by handling hierarchical transactions with parent-child relationships and lock inheritance. Distributed Locking Types Optimistic locking − No locks acquired upfront; conflicts detected at commit time. Pessimistic locking − Locks acquired before accessing shared resources; conflicts prevented from the start. MOSS Protocol MOSS is a hierarchical locking protocol for nested transactions where subtransactions can inherit locks from ancestors ? ...
Read MoreMethodologies of Large Scale Distributed Systems
Large-scale distributed systems handle massive data volumes, many concurrent users, and demanding performance requirements. Building them requires methodologies that help developers efficiently manage complexity, scalability, and fault tolerance. Companies like Google, Amazon, and Facebook use these systems extensively. Architecture of Distributed Systems Distributed systems consist of multiple nodes connected via a network, each running part of the distributed software. Understanding domain requirements, security, compliance, and future integrations is critical from the start. Node 1 Node 2 Node 3 ...
Read MoreMigrating Amazon RDS from one Region to another
Amazon RDS (Relational Database Service) is a fully-managed tool for maintaining databases. Migrating an RDS database from one region to another involves creating a snapshot, copying it to the target region, and restoring a new instance from it. Source (us-east-1) RDS Instance DB Snapshot Copy Snapshot ...
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