Lecture 7. Query execution

Readings:

• Only read Section 1 of the following humongous paper: G. Graefe. Query Evaluation Techniques for Large Databases. ACM Computing Surveys 25(2), 1993. [pdf]

As you read Secton 1 of the above paper, consider the following questions:

• What are the basic steps involved in processing a query? Note that this was also discussed in Section 4 of the paper: "Anatomy of a Database System." We did not get to that part in Lecture 5 and will discuss it in Lecture 7.
• What is the difference between logical algebra and physical algebra?
• How are operators synchronized during query execution (and how is data transferred between operators)? What are some benefits of this approach? [Do not worry how iterators are actually represented in Vocano].

Lecture notes:

• lecture7.pdf

Additional resources:

• Chapter 12 (in R&G, third edition).

Optional, additional readings:

• The rest of: G. Graefe. Query Evaluation Techniques for Large Databases. ACM Computing Surveys 25(2), 1993. [pdf]