Package edu.caltech.nanodb.plannodes

Class SortedGroupAggregateNode

java.lang.Object

edu.caltech.nanodb.plannodes.PlanNode

edu.caltech.nanodb.plannodes.GroupAggregateNode

edu.caltech.nanodb.plannodes.SortedGroupAggregateNode

All Implemented Interfaces:

java.lang.Cloneable

public class SortedGroupAggregateNode
extends GroupAggregateNode

Implements grouping and aggregation by using sorting as a method to find groups.

Field Summary

Fields

Modifier and Type	Field	Description
private TupleLiteral	currentGroupValues	A tuple of the current group-by values being considered.
private boolean	done
private static org.apache.logging.log4j.Logger	logger	A logging object for reporting anything interesting that happens.
private java.util.List<OrderByExpression>	orderByExprs

Fields inherited from class edu.caltech.nanodb.plannodes.GroupAggregateNode

aggregates, estimatedNumTuples, groupByExprs, inputSchema

Fields inherited from class edu.caltech.nanodb.plannodes.PlanNode

cost, environment, leftChild, rightChild, schema, stats

Constructor Summary

Constructors

Constructor	Description
SortedGroupAggregateNode(PlanNode subplan, java.util.List<Expression> groupByExprs, java.util.Map<java.lang.String,FunctionCall> aggregates)

Method Summary

Modifier and Type	Method	Description
void	cleanUp()	Perform any necessary clean up tasks.
boolean	equals(java.lang.Object obj)	Checks if the argument is a plan node tree with the same structure, but not necesarily the same references.
Tuple	getNextTuple()	Gets the next tuple that fulfills the conditions for this plan node.
int	hashCode()	Computes the hash-code of a plan-node, including any sub-plans of this plan.
void	initialize()	Does any initialization the node might need.
void	markCurrentPosition()	The sorted grouping/aggregate plan node doesn't support marking.
void	prepare()	This method is responsible for computing critical details about the plan node, such as the schema of the results that are produced, the estimated cost of evaluating the plan node (and its children), and statistics describing the results produced by the plan node.
boolean	requiresLeftMarking()	The sorted grouping/aggregate operation does not require marking.
boolean	requiresRightMarking()	The sorted grouping/aggregate operation does not require marking.
void	resetToLastMark()	The sorted grouping/aggregate plan node doesn't support marking.
java.util.List<OrderByExpression>	resultsOrderedBy()	The sorted grouping/aggregate operation orders its results according to the columns in the GROUP BY clause.
boolean	supportsMarking()	The sorted grouping/aggregate operation does not support marking, since it must fully consume its input before it can produce any results.
java.lang.String	toString()	Reports this node and its vital parameters as a string.

Methods inherited from class edu.caltech.nanodb.plannodes.GroupAggregateNode

clearAggregates, evaluateGroupByExprs, generateOutputTuple, prepareSchemaStats, updateAggregates

Methods inherited from class edu.caltech.nanodb.plannodes.PlanNode

addParentEnvironmentToPlanTree, clone, duplicate, getCost, getEnvironment, getSchema, getStats, printNodeTree, printNodeTree, printNodeTree, printNodeTreeToString, printNodeTreeToString, setEnvironment

Methods inherited from class java.lang.Object

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

Field Detail

logger

private static org.apache.logging.log4j.Logger logger

A logging object for reporting anything interesting that happens.

orderByExprs

private java.util.List<OrderByExpression> orderByExprs

done

private boolean done

currentGroupValues

private TupleLiteral currentGroupValues

A tuple of the current group-by values being considered. When each tuple is retrieved from the subplan, a set of group-by values is computed, and if it matches this set of group-by values then we are still in the same group; otherwise, we have moved to the next group.

Constructor Detail

SortedGroupAggregateNode

public SortedGroupAggregateNode(PlanNode subplan,
                                java.util.List<Expression> groupByExprs,
                                java.util.Map<java.lang.String,FunctionCall> aggregates)

Method Detail

equals

public boolean equals(java.lang.Object obj)

Description copied from class: PlanNode

Checks if the argument is a plan node tree with the same structure, but not necesarily the same references.

Specified by:

equals in class PlanNode

Parameters:

obj - the object to which we are comparing

hashCode

public int hashCode()

Description copied from class: PlanNode

Computes the hash-code of a plan-node, including any sub-plans of this plan. This method is used to see if two plan nodes (or subtrees) might be equal.

Specified by:

hashCode in class PlanNode

Returns:

the hash code for the plan node and any subnodes it may contain.

toString

public java.lang.String toString()

Description copied from class: PlanNode

Reports this node and its vital parameters as a string.

Specified by:

toString in class PlanNode

Returns:

the node in string format.

resultsOrderedBy

public java.util.List<OrderByExpression> resultsOrderedBy()

The sorted grouping/aggregate operation orders its results according to the columns in the GROUP BY clause.

Specified by:

resultsOrderedBy in class PlanNode

Returns:

If the plan node produces ordered results, this will be a list of objects specifying the ordering. If the node doesn't produce ordered results then the return-value will either be an empty list or it will be null.

supportsMarking

public boolean supportsMarking()

The sorted grouping/aggregate operation does not support marking, since it must fully consume its input before it can produce any results.

Overrides:

supportsMarking in class PlanNode

Returns:

true if the node supports position marking, false otherwise.

requiresLeftMarking

public boolean requiresLeftMarking()

The sorted grouping/aggregate operation does not require marking.

Overrides:

requiresLeftMarking in class PlanNode

Returns:

true if the node requires that its left child supports marking, false otherwise.

requiresRightMarking

public boolean requiresRightMarking()

The sorted grouping/aggregate operation does not require marking.

Overrides:

requiresRightMarking in class PlanNode

Returns:

true if the node requires that its right child supports marking, false otherwise.

getNextTuple

public Tuple getNextTuple()

Gets the next tuple that fulfills the conditions for this plan node. If the node has a child, it should call getNextTuple() on the child. If the node is a leaf, the tuple comes from some external source such as a table file, the network, etc.

Specified by:

getNextTuple in class PlanNode

Returns:

the next tuple to be generated by this plan, or null if the plan has finished generating plan nodes.

prepare

public void prepare()

Description copied from class: PlanNode

This method is responsible for computing critical details about the plan node, such as the schema of the results that are produced, the estimated cost of evaluating the plan node (and its children), and statistics describing the results produced by the plan node.

Specified by:

prepare in class PlanNode

initialize

public void initialize()

Does any initialization the node might need. This could include resetting state variables or starting the node over from the beginning.

Overrides:

initialize in class PlanNode

markCurrentPosition

public void markCurrentPosition()
                         throws java.lang.UnsupportedOperationException

The sorted grouping/aggregate plan node doesn't support marking.

Overrides:

markCurrentPosition in class PlanNode

Throws:

java.lang.UnsupportedOperationException - always.

resetToLastMark

public void resetToLastMark()

The sorted grouping/aggregate plan node doesn't support marking.

Overrides:

resetToLastMark in class PlanNode

Throws:

java.lang.UnsupportedOperationException - always.

cleanUp

public void cleanUp()

Perform any necessary clean up tasks. This should probably be called when we are done with this plan node.

Specified by:

cleanUp in class PlanNode