After reading this chapter, the reader will understand:

  • The steps involved in query processing
  • How SQL queries are translated into relational algebra expressions
  • The role of sort operation in database systems and the external sort–merge algorithm used for sorting
  • Various algorithms for implementing the relational algebra operations such as select operation, project operation, join operation, set operations, and aggregate operations
  • Two approaches of evaluating the expressions containing multiple operations, namely, materialized evaluation and pipelined evaluation
  • Different types of query optimization techniques, namely, cost-based query optimization, heuristics-based query optimization, and semantic ...

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