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What is meant by heuristic optimisation? Discuss the main heuristics that are applied during query optimisation.
Ans: In heuristic optimization, heuristics are employed to reduce the cost of optimization in place of analyzing the number of different plans to make out the optimal plan. For instance, a heuristic optimizer would make use of the rule 'Perform selection operation as early as possible' without finding out whether the cost is reduced by this transformation. Heuristics approach generally assists to reduce the cost but not all the time. The major heuristics that are applied throughout query optimization are:
Complete replication: It implies maintaining of a whole copy of the database at every site. Thus, the reliability & availability and performance for query response are maximized.
Question 1 Draw a Data Flow Diagram for a University scenario Question 2 Discuss the following with suitable examples Relational Algebra Operators Database Pla
What is a primary index? A primary index is an index whose search key also explains the sequential order of the file.
what is natural join?
Data independence seems that "the application is independent of the access strategy and storage structure of data". In other words, the ability to change the schema definition in o
The Locking Protocol: To manage concurrency related problems we use locking. A lock is mainly a variable that is associated with a data item in the database. A lock can be located
What is Hierarchical DBMS In HDBMS, data is structured in a tree like manner. There is a parent-child relationship between data items and the data model is very suitable for re
Drawbacks of Database systems ?
Timestamp Ordering Protocol A timestamp is a tag that can be attached to any transaction or any data item, which indicates a specific time on which the transaction or data item
project on dbms
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