Class Sample

All Implemented Interfaces:
Cloneable, RelOptNode, RelNode

public class Sample extends SingleRel
Relational expression that returns a sample of the rows from its input.

In SQL, a sample is expressed using the TABLESAMPLE BERNOULLI or SYSTEM keyword applied to a table, view or sub-query.

  • Constructor Details

  • Method Details

    • copy

      public RelNode copy(RelTraitSet traitSet, List<RelNode> inputs)
      Description copied from interface: RelNode
      Creates a copy of this relational expression, perhaps changing traits and inputs.

      Sub-classes with other important attributes are encouraged to create variants of this method with more parameters.

      Specified by:
      copy in interface RelNode
      copy in class AbstractRelNode
      traitSet - Trait set
      inputs - Inputs
      Copy of this relational expression, substituting traits and inputs
    • getSamplingParameters

      public RelOptSamplingParameters getSamplingParameters()
      Retrieve the sampling parameters for this Sample.
    • explainTerms

      public RelWriter explainTerms(RelWriter pw)
      Description copied from class: AbstractRelNode
      Describes the inputs and attributes of this relational expression. Each node should call super.explainTerms, then call the RelWriter.input(String, RelNode) and RelWriter.item(String, Object) methods for each input and attribute.
      explainTerms in class SingleRel
      pw - Plan writer
      Plan writer for fluent-explain pattern