by admin | Jun 17, 2015 | sem3
Denormalization In a relational database, denormalization is an approach to optimizing performance in which the administrator selectively adds back specific instances of duplicate data after the data structure has been normalized. In a relational database,...
by admin | Jun 17, 2015 | sem3
Database normalization forms Normalization If a database design is not perfect, it may contain anomalies, which are like a bad dream for any database administrator. Managing a database with anomalies is next to impossible. Update anomalies − If data items are...
by admin | Jun 16, 2015 | sem3
Codds Rules Dr Edgar F. Codd, once his intensive analysis on the relational Model of information systems, came up with twelve rules of his own, that consistent with him, a database should adjust so as to be considered a real relational database. These rules may be...
by admin | Jun 16, 2015 | sem3
ER Model to Relational Model In ER Model, when conceptualized into diagrams, gives a easy overview of entity-relationship, which is Simpler to understand. ER diagrams can be mapped to relational schema, that is, it is possible to create relational schema using ER...
by admin | Jun 16, 2015 | sem3
Heuristic cost estimation Using Heuristic cost estimation Process for heuristics optimization １．The parser of a high-level query generates an initial internal representation; ２．Apply heuristics rules to optimize the internal representation. ３．A query execution plan is...
by admin | Jun 16, 2015 | sem3
Query Processing and Optimization Query Processing and Optimization : Outline Operator Evaluation Strategies Query processing in general Selection Join Query Optimization Heuristic query optimization Cost-based query optimization Query Tuning Query Processing +...
