Design a query plan for distributed query, Database Management System

Assignment Help:

(a) Design a query plan for the following distributed query: An application at site B wants to compute a join of STUDENT ?Id=StudId TRANSCRIPT where STUDENT (Id,Major) is at site B and TRANSCRIPT (StudId, CrsCode) is at site C. The result should be returned to B. Assume that semijoin is not used. Also assume that

  • Value lengths are:
  1. Id and StudId are 8 bytes long;
  2. Major is 3 bytes long;
  3. CrsCode is 6 bytes long.
  • STUDENT has 15,000 tuples.
  • 6,000 students are registered for at least one course. On the average, each student is registered for 5 courses.

(b)   Estimate the cost of computing σMajor='CS' (STUDENT) ?Id = StudId TRANSCRIPT using the semijoin strategy. Use the sizes of the STUDENT and TRANSCRIPT relations and of their attributes from the part (a) above. In addition, assume that 10% of the students major in CS. Compare this with the solutions in part (a) above that do not use the semijoin.

 


Related Discussions:- Design a query plan for distributed query

Draw an e-r diagram and convert it to a relational schema, In an organisati...

In an organisation various projects are undertaken. Each projects can employ one or more employees. Every employee can work on one or more projects. Each project is undertaken on

Can your organization scan large format documents, Can your organization sc...

Can your organization scan large format documents? Yes, large format scanning used for such entities as city plans and blueprints is available. We selected scanners with the ab

Describe the types of attributes, Describe the types of attributes? Ty...

Describe the types of attributes? Types of attributes: An attribute's category determines the type of values that are permitted in the attribute. For instance, the value vers

Discuss the method for a hash file to expand shrink dynamic, Discuss the me...

Discuss the methods for a hash file to expand and shrink dynamically. What are the advantages and disadvantages of each? The hashing methods that permit dyanamic file expansi

Create a database, The database will enable college administrators the abil...

The database will enable college administrators the ability to track students initial major. This will help college officials decide how best to prepare students for their goals an

Define the canonical cover, Define the Canonical cover Ans: A canonical...

Define the Canonical cover Ans: A canonical cover F c for F is a set of dependencies like F logically implies all dependencies in F c , and F c logically entails all dependen

Need for multiple access paths, Need for Multiple Access Paths In pract...

Need for Multiple Access Paths In practice, most of the online information systems need the support of multi-key files. For example, consider a banking database application hav

The second normal form (2nf), The Second Normal Form (2NF) Definition: ...

The Second Normal Form (2NF) Definition: A relation is in 2NF if it is in 1NF and each non-key attribute is fully dependent on each candidate key of the relation. Some of th

Explain the concept of two-phase locking, Explain the Concept of Two-phase ...

Explain the Concept of Two-phase Locking It concerns the positions of locking and unlocking operations in each transaction.  In this protocol every transaction issue lock and u

Which product produces the relation that has attributes, Which product prod...

Which product produces the relation that has attributes of R1 and R2 ? Cartesian product produce the relation which has attributes of R1 and R2

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd