Class PossiblyNullDimensionSelector
- java.lang.Object
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- org.apache.druid.segment.AbstractDimensionSelector
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- org.apache.druid.segment.join.PossiblyNullDimensionSelector
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- All Implemented Interfaces:
HotLoopCallee
,BaseDoubleColumnValueSelector
,BaseFloatColumnValueSelector
,BaseLongColumnValueSelector
,BaseNullableColumnValueSelector
,BaseObjectColumnValueSelector<Object>
,ColumnValueSelector<Object>
,DimensionDictionarySelector
,DimensionSelector
,IdLookup
public class PossiblyNullDimensionSelector extends AbstractDimensionSelector implements IdLookup
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Nested Class Summary
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Nested classes/interfaces inherited from interface org.apache.druid.segment.DimensionSelector
DimensionSelector.NullDimensionSelectorHolder
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Field Summary
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Fields inherited from interface org.apache.druid.segment.ColumnValueSelector
EMPTY_ARRAY
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Fields inherited from interface org.apache.druid.segment.DimensionDictionarySelector
CARDINALITY_UNKNOWN
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Constructor Summary
Constructors Constructor Description PossiblyNullDimensionSelector(DimensionSelector baseSelector, BooleanSupplier beNull)
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description Class<?>
classOfObject()
Most-specific class of object returned byBaseObjectColumnValueSelector.getObject()
, if known in advance.IndexedInts
getRow()
Returns the indexed values at the current position in this DimensionSelector.int
getValueCardinality()
Value cardinality is the cardinality of the different occurring values.IdLookup
idLookup()
ReturnsIdLookup
if available for this DimensionSelector, or null.void
inspectRuntimeShape(RuntimeShapeInspector inspector)
Implementations of this method should callinspector.visit()
with all fields of this class, which meet two conditions: 1.int
lookupId(String name)
Inverse ofDimensionDictionarySelector.lookupName(int)
.String
lookupName(int id)
Returns the value for a particular dictionary id as a Java String.ValueMatcher
makeValueMatcher(String value)
ValueMatcher
makeValueMatcher(DruidPredicateFactory predicateFactory)
boolean
nameLookupPossibleInAdvance()
Returns true if it is possible toDimensionDictionarySelector.lookupName(int)
by ids from 0 toDimensionDictionarySelector.getValueCardinality()
before the rows with those ids are returned.-
Methods inherited from class org.apache.druid.segment.AbstractDimensionSelector
getObject
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Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
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Methods inherited from interface org.apache.druid.segment.DimensionDictionarySelector
lookupNameUtf8, supportsLookupNameUtf8
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Methods inherited from interface org.apache.druid.segment.DimensionSelector
defaultGetObject, getDouble, getFloat, getLong, isNull
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Constructor Detail
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PossiblyNullDimensionSelector
public PossiblyNullDimensionSelector(DimensionSelector baseSelector, BooleanSupplier beNull)
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Method Detail
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getRow
@Nonnull public IndexedInts getRow()
Description copied from interface:DimensionSelector
Returns the indexed values at the current position in this DimensionSelector. IMPORTANT. The returnedIndexedInts
object could generally be reused inside the implementation of DimensionSelector, i. e. this method could always return the same object for the same selector. Users of this API, such asAggregator.aggregate()
,BufferAggregator.aggregate(java.nio.ByteBuffer, int)
,AggregateCombiner.reset(org.apache.druid.segment.ColumnValueSelector)
,AggregateCombiner.fold(org.apache.druid.segment.ColumnValueSelector)
should be prepared for that and not storing the object returned from this method in their state, assuming that the object will remain unchanged even when the position of the selector changes. This may not be the case.- Specified by:
getRow
in interfaceDimensionSelector
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makeValueMatcher
@Nonnull public ValueMatcher makeValueMatcher(@Nullable String value)
- Specified by:
makeValueMatcher
in interfaceDimensionSelector
- Parameters:
value
- nullable dimension value
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makeValueMatcher
@Nonnull public ValueMatcher makeValueMatcher(DruidPredicateFactory predicateFactory)
- Specified by:
makeValueMatcher
in interfaceDimensionSelector
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getValueCardinality
public int getValueCardinality()
Description copied from interface:DimensionDictionarySelector
Value cardinality is the cardinality of the different occurring values. If there were 4 rows: A,B A B A Value cardinality would be 2. Cardinality may be unknown (e.g. the selector used by IncrementalIndex while reading input rows), in which case this method will return -1. If cardinality is unknown, you should assume this dimension selector has no dictionary, and avoid storing ids, calling "lookupId", or calling "lookupName" outside of the context of operating on a single row. If cardinality is known then it is assumed that underlying dictionary is lexicographically sorted by the encoded value. For example if there are values "A" , "B" , "C" in a column with cardinality 3 then it is assumed that id("A") < id("B") < id("C")- Specified by:
getValueCardinality
in interfaceDimensionDictionarySelector
- Returns:
- the value cardinality, or
DimensionDictionarySelector.CARDINALITY_UNKNOWN
if unknown.
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lookupName
@Nullable public String lookupName(int id)
Description copied from interface:DimensionDictionarySelector
Returns the value for a particular dictionary id as a Java String. For example, if a column has four rows: A,B A A,B B getRow() would return getRow(0) => [0 1] getRow(1) => [0] getRow(2) => [0 1] getRow(3) => [1] and then lookupName would return: lookupName(0) => A lookupName(1) => B Performance note: if you want ajava.lang.String
, always use this method. It will be at least as fast as callingDimensionDictionarySelector.lookupNameUtf8(int)
and decoding the bytes. However, if you want UTF-8 bytes, then check ifDimensionDictionarySelector.supportsLookupNameUtf8()
returns true, and if it does, useDimensionDictionarySelector.lookupNameUtf8(int)
instead.- Specified by:
lookupName
in interfaceDimensionDictionarySelector
- Parameters:
id
- id to lookup the dictionary value for- Returns:
- dictionary value for the given id, or null if the value is itself null
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nameLookupPossibleInAdvance
public boolean nameLookupPossibleInAdvance()
Description copied from interface:DimensionDictionarySelector
Returns true if it is possible toDimensionDictionarySelector.lookupName(int)
by ids from 0 toDimensionDictionarySelector.getValueCardinality()
before the rows with those ids are returned.Returns false if
DimensionDictionarySelector.lookupName(int)
could be called with ids, returned from the most recent row (or row vector) returned by this DimensionSelector, but not earlier. IfDimensionDictionarySelector.getValueCardinality()
of this selector additionally returnsDimensionDictionarySelector.CARDINALITY_UNKNOWN
,lookupName()
couldn't be called with ids, returned by not the most recent row (or row vector), i. e. names for ids couldn't be looked up "later". IfDimensionDictionarySelector.getValueCardinality()
returns a non-negative number,lookupName()
could be called with any ids, returned from rows (or row vectors) returned since the creation of this DimensionSelector.If
DimensionDictionarySelector.lookupName(int)
is called with an ineligible id, result is undefined: exception could be thrown, or null returned, or some other random value.- Specified by:
nameLookupPossibleInAdvance
in interfaceDimensionDictionarySelector
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idLookup
@Nullable public IdLookup idLookup()
Description copied from interface:DimensionDictionarySelector
ReturnsIdLookup
if available for this DimensionSelector, or null.- Specified by:
idLookup
in interfaceDimensionDictionarySelector
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lookupId
public int lookupId(@Nullable String name)
Description copied from interface:IdLookup
Inverse ofDimensionDictionarySelector.lookupName(int)
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inspectRuntimeShape
public void inspectRuntimeShape(RuntimeShapeInspector inspector)
Description copied from interface:HotLoopCallee
Implementations of this method should callinspector.visit()
with all fields of this class, which meet two conditions: 1. They are used in methods of this class, annotated withCalledFromHotLoop
2. They are either: a. Nullable objects b. Instances of HotLoopCallee c. Objects, which don't always have a specific class in runtime. For example, a field of typeSet
could beHashSet
orTreeSet
in runtime, depending on how this instance (the instance on which inspectRuntimeShape() is called) is configured. d. ByteBuffer or similar objects, where byte order matters e. boolean flags, affecting branch taking f. Arrays of objects, meeting any of conditions a-e.- Specified by:
inspectRuntimeShape
in interfaceHotLoopCallee
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classOfObject
public Class<?> classOfObject()
Description copied from interface:BaseObjectColumnValueSelector
Most-specific class of object returned byBaseObjectColumnValueSelector.getObject()
, if known in advance. This method returnsObject
when selectors do not know in advance what class of object they may return.- Specified by:
classOfObject
in interfaceBaseObjectColumnValueSelector<Object>
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