Package org.apache.druid.segment.vector

Class NilVectorSelector

java.lang.Object

org.apache.druid.segment.vector.NilVectorSelector

All Implemented Interfaces:

DimensionDictionarySelector, IdLookup, SingleValueDimensionVectorSelector, VectorObjectSelector, VectorSizeInspector, VectorValueSelector

public class NilVectorSelector
extends Object
implements VectorValueSelector, VectorObjectSelector, SingleValueDimensionVectorSelector, IdLookup

Field Summary

Fields inherited from interface org.apache.druid.segment.DimensionDictionarySelector

CARDINALITY_UNKNOWN

Method Summary

Modifier and Type	Method	Description
static NilVectorSelector	create(VectorSizeInspector vectorSizeInspector)
int	getCurrentVectorSize()	Returns the current vector size for this cursor.
double[]	getDoubleVector()	Get the current vector, casting to doubles as necessary.
float[]	getFloatVector()	Get the current vector, casting to floats as necessary.
long[]	getLongVector()	Get the current vector, casting to longs as necessary.
int	getMaxVectorSize()	Returns the maximum vector size for this cursor.
boolean[]	getNullVector()	Gets a vector of booleans signifying which rows are null and which are not (true for null).
Object[]	getObjectVector()	Get the current vector.
int[]	getRowVector()	Get the current vector.
int	getValueCardinality()	Value cardinality is the cardinality of the different occurring values.
IdLookup	idLookup()	Returns IdLookup if available for this DimensionSelector, or null.
int	lookupId(String name)	Inverse of DimensionDictionarySelector.lookupName(int).
String	lookupName(int id)	Returns the value for a particular dictionary id as a Java String.
boolean	nameLookupPossibleInAdvance()	Returns true if it is possible to DimensionDictionarySelector.lookupName(int) by ids from 0 to DimensionDictionarySelector.getValueCardinality() before the rows with those ids are returned.

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.druid.segment.DimensionDictionarySelector

lookupNameUtf8, supportsLookupNameUtf8

Method Detail

create

public static NilVectorSelector create(VectorSizeInspector vectorSizeInspector)

getLongVector

public long[] getLongVector()

Description copied from interface: VectorValueSelector

Get the current vector, casting to longs as necessary. The array will be reused, so it is not a good idea to retain a reference to it.

Specified by:

getLongVector in interface VectorValueSelector

getFloatVector

public float[] getFloatVector()

Description copied from interface: VectorValueSelector

Get the current vector, casting to floats as necessary. The array will be reused, so it is not a good idea to retain a reference to it.

Specified by:

getFloatVector in interface VectorValueSelector

getDoubleVector

public double[] getDoubleVector()

Description copied from interface: VectorValueSelector

Get the current vector, casting to doubles as necessary. The array will be reused, so it is not a good idea to retain a reference to it.

Specified by:

getDoubleVector in interface VectorValueSelector

getNullVector

@Nullable
public boolean[] getNullVector()

Description copied from interface: VectorValueSelector

Gets a vector of booleans signifying which rows are null and which are not (true for null). Returns null if it is known that there are no nulls in the vector, possibly because the column is non-nullable.

Specified by:

getNullVector in interface VectorValueSelector

getRowVector

public int[] getRowVector()

Description copied from interface: SingleValueDimensionVectorSelector

Get the current vector. The array will be reused, so it is not a good idea to retain a reference to it.

Specified by:

getRowVector in interface SingleValueDimensionVectorSelector

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 interface DimensionDictionarySelector

Returns:

the value cardinality, or DimensionDictionarySelector.CARDINALITY_UNKNOWN if unknown.

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 a java.lang.String, always use this method. It will be at least as fast as calling DimensionDictionarySelector.lookupNameUtf8(int) and decoding the bytes. However, if you want UTF-8 bytes, then check if DimensionDictionarySelector.supportsLookupNameUtf8() returns true, and if it does, use DimensionDictionarySelector.lookupNameUtf8(int) instead.

Specified by:

lookupName in interface DimensionDictionarySelector

Parameters:

id - id to lookup the dictionary value for

Returns:

dictionary value for the given id, or null if the value is itself null

nameLookupPossibleInAdvance

public boolean nameLookupPossibleInAdvance()

Description copied from interface: DimensionDictionarySelector

Returns true if it is possible to DimensionDictionarySelector.lookupName(int) by ids from 0 to DimensionDictionarySelector.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. If DimensionDictionarySelector.getValueCardinality() of this selector additionally returns DimensionDictionarySelector.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". If DimensionDictionarySelector.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 interface DimensionDictionarySelector

idLookup

@Nullable
public IdLookup idLookup()

Description copied from interface: DimensionDictionarySelector

Returns IdLookup if available for this DimensionSelector, or null.

Specified by:

idLookup in interface DimensionDictionarySelector

lookupId

public int lookupId(@Nullable
                    String name)

Description copied from interface: IdLookup

Inverse of DimensionDictionarySelector.lookupName(int).

Specified by:

lookupId in interface IdLookup

getObjectVector

public Object[] getObjectVector()

Description copied from interface: VectorObjectSelector

Get the current vector. The type of objects in the array depends on the type of the selector. Callers can determine this by calling VectorColumnSelectorFactory.getColumnCapabilities(String) if creating selectors directly. Alternatively, callers using VectorColumnProcessorFactory will receive capabilities as part of the callback to VectorColumnProcessorFactory.makeObjectProcessor(ColumnCapabilities, VectorObjectSelector). String selectors, where type is ColumnType.STRING, must use objects compatible with the spec of DimensionSelector.rowToObject(IndexedInts, DimensionDictionarySelector). Array selectors, where TypeSignature.isArray(), must use Object[]. The array may contain null elements, and the array itself may also be null. Complex selectors may use any type of object. No other type of selector is possible. Vector object selectors are only used for strings, arrays, and complex types.

Specified by:

getObjectVector in interface VectorObjectSelector

getCurrentVectorSize

public int getCurrentVectorSize()

Description copied from interface: VectorSizeInspector

Returns the current vector size for this cursor. Will never be larger than the max size returned by VectorSizeInspector.getMaxVectorSize().

Specified by:

getCurrentVectorSize in interface VectorSizeInspector

getMaxVectorSize

public int getMaxVectorSize()

Description copied from interface: VectorSizeInspector

Returns the maximum vector size for this cursor. It will not change for the lifetime of this cursor, and is generally used to allocate scratch arrays for later processing. Will always be greater than zero.

Specified by:

getMaxVectorSize in interface VectorSizeInspector