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Notations for the Physical Query Plan

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• Physical query plan (tree)
  • Structure of a logical query plan:

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  • Physical query plan:

    Physical query plan = the (optimized) logical query plan with each node replaced by one or more physical operators used to implement the relational algebra operation

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• The leaf nodes
  • Fact:

    The leaves of a logical query plan is always a relation

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  • Consequently:

    The leaves of a physical query plan is also a relation In addition, we also need to specify: a Scan-operator Possible scan-operators: Table-Scan(R) Index-Scan(R) See: click here

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• Pipelining and Materialization
  • Notation for pipelining:

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  • Notation for materialization:

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• Notation to specify physical operation
  • Notation:

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• Example 1: materialization
  • Logical query plan:

    From the example here: click here where we materialize the result: Operators used: ⋈1 is implemented with a 2-pass join algorithm based on hashing using 101 buffers ⋈2 is also implemented with a 2-pass join algorithm based on hashing using 101 buffers

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  • The physical query plan:

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• Example 2: pipelining
  • Logical query plan:

    From the example here: click here where we pipeline the result: Operators used: ⋈1 is implemented with a 2-pass join algorithm based on hashing using 101 buffers ⋈2 is implemented with a one-pass join algorithm using 50 buffers

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  • The physical query plan:

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• Example 3: filter
  • Logical query plan:

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  • Physical query plan: