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RDBMS Articles
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Object-Relational Features_ Object Database Extensions to SQL
The object-relational model combines relational databases with object database features. SQL (starting from SQL:1999 and refined in SQL:2008) incorporates object extensions including user-defined types, object identity, encapsulation, and inheritance. Key Object Features in SQL Feature Description Type Constructors ROW type (struct), ARRAY, SET, LIST, BAG for complex objects Object Identity REF types provide unique object identifiers (OIDs) Encapsulation Methods defined within UDTs (User-Defined Types) Inheritance UNDER keyword for type and table inheritance User-Defined Types (UDTs) UDTs allow creating complex-structured objects with custom attributes and ...
Read MoreObject Database Conceptual Design
An object database stores data as objects (containing both data and methods), working directly with object-oriented programming languages like Java and Python. Object-oriented modeling supports inheritance, encapsulation, and polymorphism, making it more flexible than the traditional relational model for complex relationships. ODB vs RDB Conceptual Design Feature Object Database (ODB) Relational Database (RDB) Relationships OID references (single or collections) Matching attribute values (foreign keys) Inheritance Built-in (extends, derives) No built-in construct Operations Part of class definition, specified early Can be delayed to implementation Multivalued Attributes Supported (set, bag, ...
Read MoreNumber 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 MoreMySQL Recursive CTE (Common Table Expressions)
A Recursive CTE (Common Table Expression) is a subquery that references itself using its own name. It is defined using WITH RECURSIVE and must have a terminating condition. Recursive CTEs are useful for generating series, traversing hierarchical data, and graph traversals. Syntax WITH RECURSIVE cte_name (col1, col2, ...) AS ( -- Non-recursive (base case): initial rows SELECT col1, col2 FROM table_name UNION ALL -- Recursive case: references cte_name SELECT col1, col2 FROM cte_name WHERE condition ) SELECT ...
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 MoreMultilevel Association Rule in data mining
Association rule mining discovers relationships between items in a dataset using "If A, then B" rules measured by support (frequency) and confidence (reliability). Multilevel association rule mining extends this to find relationships at different levels of granularity − for example, between individual products and product categories. Association Rule Basics The Apriori algorithm is widely used for mining association rules. It iteratively generates candidate itemsets and prunes those below support/confidence thresholds. Electronics Laptops Phones ...
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 MoreNode in Apache Cassandra
Apache Cassandra is an open-source NoSQL database written in Java, designed for high availability with no single point of failure. Nodes are the fundamental building blocks of Cassandra's distributed architecture, forming a peer-to-peer ring structure. Node in Cassandra Each node holds actual data along with metadata (location, data center, keyspaces, tables, schema). Nodes form a ring where every node is equal − no master/slave hierarchy. Data is distributed across nodes using a partitioner, and replicas are stored on multiple nodes for fault tolerance. ...
Read MoreNO-UNDO REDO Recovery Based on Deferred Update
In deferred update recovery, actual database modifications on disk are postponed until a transaction commits. Updates are recorded only in the log and cache buffers during execution. If a transaction fails before commit, the database on disk remains unaffected − hence NO-UNDO. Only REDO is needed for committed transactions whose changes haven't been written to disk. Deferred Update Protocol A transaction cannot modify the database on disk until it reaches its commit point. All REDO log entries must be force-written to disk before commit (Write-Ahead Logging). Only REDO log entries (new values/AFIM) are needed − no UNDO ...
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