org.apache.calcite.sql2rel

Class RelFieldTrimmer.TrimResult

java.lang.Object

org.apache.calcite.util.Pair<RelNode,Mapping>

org.apache.calcite.sql2rel.RelFieldTrimmer.TrimResult

All Implemented Interfaces:

Serializable, Comparable<Pair<RelNode,Mapping>>, Map.Entry<RelNode,Mapping>

Enclosing class:

RelFieldTrimmer

protected static class RelFieldTrimmer.TrimResult
extends Pair<RelNode,Mapping>

Result of an attempt to trim columns from a relational expression.

The mapping describes where to find the columns wanted by the parent of the current relational expression.

The mapping is a Mappings.SourceMapping, which means that no column can be used more than once, and some columns are not used. columnsUsed.getSource(i) returns the source of the i'th output field.

For example, consider the mapping for a relational expression that has 4 output columns but only two are being used. The mapping {2 → 1, 3 → 0} would give the following behavior:

• columnsUsed.getSourceCount() returns 4
• columnsUsed.getTargetCount() returns 2
• columnsUsed.getSource(0) returns 3
• columnsUsed.getSource(1) returns 2
• columnsUsed.getSource(2) throws IndexOutOfBounds
• columnsUsed.getTargetOpt(3) returns 0
• columnsUsed.getTargetOpt(0) returns -1

See Also:

Serialized Form

Field Summary

Fields inherited from class org.apache.calcite.util.Pair

left, right

Constructor Summary

Constructors

Constructor and Description
RelFieldTrimmer.TrimResult(RelNode left, Mapping right) Creates a TrimResult.

Method Summary

Methods inherited from class org.apache.calcite.util.Pair

adjacents, compareTo, equals, firstAnd, getKey, getValue, hashCode, left, left, of, right, right, setValue, toMap, toString, zip, zip, zip, zip

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

RelFieldTrimmer.TrimResult

public RelFieldTrimmer.TrimResult(RelNode left,
                          Mapping right)

Creates a TrimResult.

Parameters:

left - New relational expression

right - Mapping of fields onto original fields