Module datarush.library

Package com.pervasive.datarush.operators.join

Class Join

java.lang.Object

com.pervasive.datarush.operators.AbstractLogicalOperator

com.pervasive.datarush.operators.CompositeOperator

com.pervasive.datarush.operators.join.AbstractRelationalJoin

com.pervasive.datarush.operators.join.Join

All Implemented Interfaces:

LogicalOperator

public final class Join
extends AbstractRelationalJoin

Performs a relational equi-join on two input datasets by a specified set of keys. Depending on the value of AbstractRelationalJoin.getUseHashJoinHint() one of two procedures are used.

1. If hash join hint is false, input data will be sorted and hash partitioned by the specified keys (if not already sorted according to upstream metadata). Once sorted and partitioned, data is is them combined in a streaming fashion. Note that if a key group contains multiple rows on both sides, then all combinations of left and right rows in the key group appear in the output for that key group. In this case, memory consumption is lower if the side with more key repetition is linked to the left input.
2. If hash join hint is true, a full copy of the data from the right will be distributed to the cluster and loaded into memory within each node in the cluster. The left side will not be sorted or partitioned. Thus, the right side should always be small.

NOTE: hash join hint is currently ignored if join mode is JoinMode.FULL_OUTER or JoinMode.RIGHT_OUTER.

Constructor Summary

Constructors

Constructor	Description
Join()	Default constructor.
Join(JoinKey[] joinKeys)	Performs a join with the given set of join keys
Join(List<JoinKey> joinKeys)	Performs a join with the given set of join keys

Method Summary

Modifier and Type	Method	Description
protected RecordPort	composeJoin(CompositionContext ctx, RecordPort left, RecordPort right, JoinKey[] keys)
JoinMode	getJoinMode()	Returns the join mode to use when performing a join.
boolean	isMergeLeftAndRightKeys()	Returns whether to merge the left and right key fields into a single field for output.
void	setJoinMode(JoinMode joinMode)	Sets the join mode to use when performing a join.
void	setMergeLeftAndRightKeys(boolean mergeLeftAndRightKeys)	Sets whether to merge the left and right key fields into a single field for output.

Methods inherited from class com.pervasive.datarush.operators.join.AbstractRelationalJoin

compose, getJoinCondition, getJoinKeys, getLeft, getOutput, getRight, getUseHashJoinHint, newJoinID, setJoinCondition, setJoinCondition, setJoinKeys, setJoinKeys, setJoinKeys, setJoinKeys, setUseHashJoinHint

Methods inherited from class com.pervasive.datarush.operators.AbstractLogicalOperator

disableParallelism, getInputPorts, getOutputPorts, newInput, newInput, newOutput, newRecordInput, newRecordInput, newRecordOutput, notifyError

Methods inherited from class java.lang.Object

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

Constructor Detail

Join

public Join()

Default constructor. Prior to graph compilation, the following property must be set:

• joinKeys

Join

public Join(JoinKey[] joinKeys)

Performs a join with the given set of join keys

Parameters:

joinKeys - the join keys

Join

public Join(List<JoinKey> joinKeys)

Performs a join with the given set of join keys

Parameters:

joinKeys - the join keys

Method Detail

isMergeLeftAndRightKeys

public boolean isMergeLeftAndRightKeys()

Returns whether to merge the left and right key fields into a single field for output. If true, output keys will be the widest type of left and right types and will be named after the left. If false, left and right keys will be output independently. False by-default.

Returns:

whether to merge the left and right key fields into a single field for output

setMergeLeftAndRightKeys

public void setMergeLeftAndRightKeys(boolean mergeLeftAndRightKeys)

Sets whether to merge the left and right key fields into a single field for output. If true, output keys will be the widest type of left and right types and will be named after the left. If false, left and right keys will be output independently. False by-default.

Parameters:

mergeLeftAndRightKeys - whether to merge the left and right key fields into a single field for output

getJoinMode

public JoinMode getJoinMode()

Returns the join mode to use when performing a join. JoinMode.INNER by default.

Returns:

the join mode to use when performing a join.

setJoinMode

public void setJoinMode(JoinMode joinMode)

Sets the join mode to use when performing a join. JoinMode.INNER by default.

Parameters:

joinMode - the join mode to use when performing a join.

composeJoin

protected RecordPort composeJoin(CompositionContext ctx,
                                 RecordPort left,
                                 RecordPort right,
                                 JoinKey[] keys)

Specified by:

composeJoin in class AbstractRelationalJoin