org.apache.calcite.rel.core

Class Sample

java.lang.Object

org.apache.calcite.rel.AbstractRelNode

org.apache.calcite.rel.SingleRel

org.apache.calcite.rel.core.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 subquery.

Field Summary

Fields inherited from class org.apache.calcite.rel.AbstractRelNode

digest, id, rowType, traitSet

Constructor Summary

Constructors

Constructor and Description
Sample(RelInput input) Creates a Sample by parsing serialized output.
Sample(RelOptCluster cluster, RelNode child, RelOptSamplingParameters params)

Method Summary

Methods

Modifier and Type	Method and Description
RelNode	copy(RelTraitSet traitSet, List<RelNode> inputs) Creates a copy of this relational expression, perhaps changing traits and inputs.
RelWriter	explainTerms(RelWriter pw) Describes the inputs and attributes of this relational expression.
RelOptSamplingParameters	getSamplingParameters() Retrieve the sampling parameters for this Sample.

Methods inherited from class org.apache.calcite.rel.SingleRel

childrenAccept, deriveRowType, getInput, getInputs, getRows, replaceInput

Methods inherited from class org.apache.calcite.rel.AbstractRelNode

accept, accept, collectVariablesSet, collectVariablesUsed, computeDigest, computeSelfCost, explain, getChildExps, getCluster, getCollationList, getConvention, getCorrelVariable, getDescription, getDigest, getExpectedInputRowType, getId, getInput, getQuery, getRelTypeName, getRowType, getTable, getTraitSet, getVariablesStopped, isDistinct, isKey, isValid, metadata, onRegister, recomputeDigest, register, sole, toString

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

Sample

public Sample(RelOptCluster cluster,
      RelNode child,
      RelOptSamplingParameters params)

Sample

public Sample(RelInput input)

Creates a Sample by parsing serialized output.

Method Detail

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

Overrides:

copy in class AbstractRelNode

Parameters:

traitSet - Trait set

inputs - Inputs

Returns:

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 RelWriterImpl.input(String, RelNode) and RelWriterImpl.item(String, Object) methods for each input and attribute.

Overrides:

explainTerms in class SingleRel

Parameters:

pw - Plan writer

Returns:

Plan writer for fluent-explain pattern