Class GroupMaker
- java.lang.Object
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- org.apache.cassandra.db.aggregation.GroupMaker
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public abstract class GroupMaker extends java.lang.Object
AGroupMaker
can be used to determine if some sorted rows belongs to the same group or not.
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Field Summary
Fields Modifier and Type Field Description static GroupMaker
GROUP_EVERYTHING
GroupMaker
that groups all the rows together.
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Constructor Summary
Constructors Constructor Description GroupMaker()
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Method Summary
All Methods Static Methods Instance Methods Abstract Methods Concrete Methods 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
newInstance(ClusteringComparator comparator, int clusteringPrefixSize)
static GroupMaker
newInstance(ClusteringComparator comparator, int clusteringPrefixSize, GroupingState state)
boolean
returnAtLeastOneRow()
Specify if at least one row must be returned.
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Field Detail
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GROUP_EVERYTHING
public static final GroupMaker GROUP_EVERYTHING
GroupMaker
that groups all the rows together.
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Method Detail
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newInstance
public static GroupMaker newInstance(ClusteringComparator comparator, int clusteringPrefixSize, GroupingState state)
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newInstance
public static GroupMaker newInstance(ClusteringComparator comparator, int clusteringPrefixSize)
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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.
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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.
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