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What a query execution plan?
- Discuss the reasons for converting SQL queries into relational algebra queries before optimization is done.
- Explain the three factors that influence the cost of a query.
- A file of 4096 blocks is to be sorted with an available buffer space of 64 blocks. How many passes will be needed in the merge phase of the external sort-merge algorithm?
- In a particular transaction, the number of file blocks of data to be fetched is 6 while the size of entire file is 2048 blocks; evaluate the number of initial runs the transaction has to make.
- How does a query tree represent a relational algebra expression? What is meant by an execution of a query tree? Discuss the rules for transformation of query tree, and identify when each rule should be applied during optimization.
- Query optimization is a misnomer. Explain
- Consider the following S table from a students’ database;