org.apache.drill.exec.planner.physical.visitor

Class TopProjectVisitor

java.lang.Object

org.apache.drill.exec.planner.physical.visitor.BasePrelVisitor<Prel,Void,RuntimeException>

org.apache.drill.exec.planner.physical.visitor.TopProjectVisitor

All Implemented Interfaces:

PrelVisitor<Prel,Void,RuntimeException>

public class TopProjectVisitor
extends BasePrelVisitor<Prel,Void,RuntimeException>

Adds non-trivial top project to ensure the final output field names are preserved. Such non-trivial project is needed due to Calcite's behavior of ProjectRemoveRule. It will be added under Screen/Writer operator in the physical plan if there is no other Projects under these operators, in cases like * column expansion or partition by column processing.

Field Summary

Fields inherited from interface org.apache.drill.exec.planner.physical.visitor.PrelVisitor

logger

Constructor Summary

Constructors

Constructor and Description
TopProjectVisitor(org.apache.calcite.rel.type.RelDataType validatedRowType)

Method Summary

Methods

Modifier and Type	Method and Description
static Prel	insertTopProject(Prel prel, org.apache.calcite.rel.type.RelDataType validatedRowType) Traverses passed physical relational node and its children and checks if top project should be added under screen or writer to preserve final output fields names.
Prel	visitPrel(Prel prel, Void value)
Prel	visitScreen(ScreenPrel prel, Void value)
Prel	visitWriter(WriterPrel prel, Void value)

Methods inherited from class org.apache.drill.exec.planner.physical.visitor.BasePrelVisitor

visitExchange, visitJoin, visitProject, visitScan

Methods inherited from class java.lang.Object

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

Constructor Detail

TopProjectVisitor

public TopProjectVisitor(org.apache.calcite.rel.type.RelDataType validatedRowType)

Method Detail

insertTopProject

public static Prel insertTopProject(Prel prel,
                    org.apache.calcite.rel.type.RelDataType validatedRowType)

Traverses passed physical relational node and its children and checks if top project should be added under screen or writer to preserve final output fields names.

Parameters:

prel - physical relational node

validatedRowType - final output row type

Returns:

physical relational node with added project if necessary

visitPrel

public Prel visitPrel(Prel prel,
             Void value)
               throws RuntimeException

Specified by:

visitPrel in interface PrelVisitor<Prel,Void,RuntimeException>

Overrides:

visitPrel in class BasePrelVisitor<Prel,Void,RuntimeException>

Throws:

RuntimeException

visitScreen

public Prel visitScreen(ScreenPrel prel,
               Void value)

Specified by:

visitScreen in interface PrelVisitor<Prel,Void,RuntimeException>

Overrides:

visitScreen in class BasePrelVisitor<Prel,Void,RuntimeException>

visitWriter

public Prel visitWriter(WriterPrel prel,
               Void value)

Specified by:

visitWriter in interface PrelVisitor<Prel,Void,RuntimeException>

Overrides:

visitWriter in class BasePrelVisitor<Prel,Void,RuntimeException>