# What a query execution plan? 2. Discuss the reasons for converting SQL queries into relational algebra queries before optimization is done. 3. Explain the three factors that influence the cost of a query. 4. 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? 5. 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. 6. 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. 7. Query optimization is a misnomer. Explain 8. Consider the following S table from a students’ database;

What a query execution plan?

1. Discuss the reasons for converting SQL queries into relational algebra queries before optimization is done.
2. Explain the three factors that influence the cost of a query.
3. 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?
4. 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.
5. 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.
6. Query optimization is a misnomer. Explain
7. Consider the following S table from a students’ database;