Package org.apache.cassandra.db.aggregation

Class GroupMaker

java.lang.Object

org.apache.cassandra.db.aggregation.GroupMaker

public abstract class GroupMaker
extends java.lang.Object

A GroupMaker can be used to determine if some sorted rows belongs to the same group or not.

Field Summary

Fields

Modifier and Type	Field	Description
static GroupMaker	GROUP_EVERYTHING	GroupMaker that groups all the rows together.

Constructor Summary

Constructors

Constructor	Description
GroupMaker()

Method Summary

Modifier and Type	Method	Description
abstract boolean	isNewGroup(DecoratedKey partitionKey, Clustering<?> clustering)	Checks if a given row belongs to the same group that the previous row or not.
static GroupMaker	newPkPrefixGroupMaker(ClusteringComparator comparator, int clusteringPrefixSize)
static GroupMaker	newPkPrefixGroupMaker(ClusteringComparator comparator, int clusteringPrefixSize, GroupingState state)
static GroupMaker	newSelectorGroupMaker(ClusteringComparator comparator, int clusteringPrefixSize, Selector selector, java.util.List<ColumnMetadata> columns)
static GroupMaker	newSelectorGroupMaker(ClusteringComparator comparator, int clusteringPrefixSize, Selector selector, java.util.List<ColumnMetadata> columns, GroupingState state)
boolean	returnAtLeastOneRow()	Specify if at least one row must be returned.

Methods inherited from class java.lang.Object

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

Field Detail

GROUP_EVERYTHING

public static final GroupMaker GROUP_EVERYTHING

GroupMaker that groups all the rows together.

Constructor Detail

GroupMaker

public GroupMaker()

Method Detail

newPkPrefixGroupMaker

public static GroupMaker newPkPrefixGroupMaker(ClusteringComparator comparator,
                                               int clusteringPrefixSize,
                                               GroupingState state)

newPkPrefixGroupMaker

public static GroupMaker newPkPrefixGroupMaker(ClusteringComparator comparator,
                                               int clusteringPrefixSize)

newSelectorGroupMaker

public static GroupMaker newSelectorGroupMaker(ClusteringComparator comparator,
                                               int clusteringPrefixSize,
                                               Selector selector,
                                               java.util.List<ColumnMetadata> columns,
                                               GroupingState state)

newSelectorGroupMaker

public static GroupMaker newSelectorGroupMaker(ClusteringComparator comparator,
                                               int clusteringPrefixSize,
                                               Selector selector,
                                               java.util.List<ColumnMetadata> columns)

isNewGroup

public abstract boolean isNewGroup(DecoratedKey partitionKey,
                                   Clustering<?> clustering)

Checks if a given row belongs to the same group that the previous row or not.

Parameters:

partitionKey - the partition key.

clustering - the row clustering key

Returns:

true if the row belongs to the same group that the previous one, false otherwise.

returnAtLeastOneRow

public boolean returnAtLeastOneRow()

Specify if at least one row must be returned. If the selection is performing some aggregations on all the rows, one row should be returned even if no records were processed.

Returns:

true if at least one row must be returned, false otherwise.