Package org.apache.druid.segment

Class VirtualColumns

java.lang.Object

org.apache.druid.segment.VirtualColumns

All Implemented Interfaces:

Cacheable

public class VirtualColumns
extends Object
implements Cacheable

Class allowing lookup and usage of virtual columns.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	VirtualColumns.JsonIncludeFilter	JsonInclude filter for getVirtualColumns().

Field Summary

Fields

Modifier and Type	Field	Description
static final VirtualColumns	EMPTY

Method Summary

Modifier and Type	Method	Description
boolean	canVectorize(ColumnInspector columnInspector)
static VirtualColumns	create(Collection<VirtualColumn> virtualColumns)
static VirtualColumns	create(VirtualColumn... virtualColumns)
boolean	equals(Object o)
boolean	exists(String columnName)	Returns true if a virtual column exists with a particular columnName.
VirtualColumn	findEquivalent(VirtualColumns otherVirtualColumns, VirtualColumn otherVirtualColumn)	Check if virtualColumns contains a virtual column which is equivalent to some other virtual column, ignoring output name, returning it if it exists or null if there is no equivalent virtual column.
static VirtualColumns	fromIterable(Iterable<VirtualColumn> virtualColumns)
byte[]	getCacheKey()	Get a byte array used as a cache key.
ColumnCapabilities	getColumnCapabilitiesWithFallback(ColumnInspector inspector, String columnName)	Get capabilities for the column "columnName".
List<String>	getColumnNames()
ColumnIndexSupplier	getIndexSupplier(String columnName, ColumnIndexSelector columnIndexSelector)	Get the ColumnIndexSupplier of the specified virtual column, with the assistance of a ColumnSelector to allow reading things from segments.
VirtualColumn	getVirtualColumn(String columnName)
VirtualColumn[]	getVirtualColumns()
int	hashCode()
boolean	isEmpty()
ColumnValueSelector<?>	makeColumnValueSelector(String columnName, ColumnSelectorFactory selectorFactory, ColumnSelector columnSelector, ReadableOffset offset)	Create a column value selector.
DimensionSelector	makeDimensionSelector(DimensionSpec dimensionSpec, ColumnSelectorFactory selectorFactory, ColumnSelector columnSelector, ReadableOffset offset)	Create a dimension (string) selector.
MultiValueDimensionVectorSelector	makeMultiValueDimensionVectorSelector(DimensionSpec dimensionSpec, VectorColumnSelectorFactory factory, ColumnSelector columnSelector, ReadableVectorOffset offset)	Create a multi value dimension vector (string) selector.
SingleValueDimensionVectorSelector	makeSingleValueDimensionVectorSelector(DimensionSpec dimensionSpec, VectorColumnSelectorFactory factory, ColumnSelector columnSelector, ReadableVectorOffset offset)	Create a single value dimension vector (string) selector.
VectorObjectSelector	makeVectorObjectSelector(String columnName, VectorColumnSelectorFactory factory, ColumnSelector columnSelector, ReadableVectorOffset offset)	Create a column vector object selector.
VectorValueSelector	makeVectorValueSelector(String columnName, VectorColumnSelectorFactory factory, ColumnSelector columnSelector, ReadableVectorOffset offset)	Create a column vector value selector.
static VirtualColumns	nullToEmpty(VirtualColumns virtualColumns)
static Pair<String,String>	splitColumnName(String columnName)	Split a dot-style columnName into the "main" columnName and the subColumn name after the dot.
String	toString()
ColumnSelectorFactory	wrap(ColumnSelectorFactory baseFactory)	Creates a VirtualizedColumnSelectorFactory which can create column selectors for virtualColumns in addition to selectors for all physical columns in the underlying factory.
ColumnInspector	wrapInspector(ColumnInspector inspector)	Creates a VirtualizedColumnInspector that provides ColumnCapabilities information for all virtualColumns in addition to the capabilities of all physical columns in the underlying inspector.

Methods inherited from class java.lang.Object

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

Field Details

EMPTY

public static final VirtualColumns EMPTY

Method Details

splitColumnName

public static Pair<String,String> splitColumnName(String columnName)

Split a dot-style columnName into the "main" columnName and the subColumn name after the dot. Useful for columns that support dot notation.

Parameters:

columnName - columnName like "foo" or "foo.bar"

Returns:

pair of main column name (will not be null) and subColumn name (may be null)

create

public static VirtualColumns create(@Nullable
 Collection<VirtualColumn> virtualColumns)

create

public static VirtualColumns create(VirtualColumn... virtualColumns)

fromIterable

public static VirtualColumns fromIterable(Iterable<VirtualColumn> virtualColumns)

nullToEmpty

public static VirtualColumns nullToEmpty(@Nullable
 VirtualColumns virtualColumns)

exists

public boolean exists(String columnName)

Returns true if a virtual column exists with a particular columnName.

Parameters:

columnName - the column name

Returns:

true or false

getVirtualColumn

@Nullable
public VirtualColumn getVirtualColumn(String columnName)

findEquivalent

@Nullable
public VirtualColumn findEquivalent(VirtualColumns otherVirtualColumns,
 VirtualColumn otherVirtualColumn)

Check if virtualColumns contains a virtual column which is equivalent to some other virtual column, ignoring output name, returning it if it exists or null if there is no equivalent virtual column.

If the other virtual column depends on other virtual columns (from the supplied VirtualColumns), this method will attempt to locate equivalent entries in virtualColumns to build a map of equivalent output names. Then, we rewrite the inputs of the other virtual column using VirtualColumn.rewriteRequiredColumns(Map) so that differently named inputs are normalized prior to testing for equivalence.

getIndexSupplier

@Nullable
public ColumnIndexSupplier getIndexSupplier(String columnName,
 ColumnIndexSelector columnIndexSelector)

Get the ColumnIndexSupplier of the specified virtual column, with the assistance of a ColumnSelector to allow reading things from segments. Returns null if the virtual column wants to act like a missing column. Returns NoIndexesColumnIndexSupplier.getInstance() if the virtual column does not support indexes and wants cursor-based filtering.

Throws:

IllegalArgumentException - if the virtual column does not exist (see exists(String)

makeDimensionSelector

public DimensionSelector makeDimensionSelector(DimensionSpec dimensionSpec,
 ColumnSelectorFactory selectorFactory,
 @Nullable
 ColumnSelector columnSelector,
 @Nullable
 ReadableOffset offset)

Create a dimension (string) selector.

Parameters:

dimensionSpec - spec the column was referenced with

selectorFactory - object for fetching underlying selectors.

columnSelector - object for fetching underlying columns, if available.

offset - offset to use with underlying columns. Must be provided if columnSelector is provided.

Throws:

IllegalArgumentException - if the virtual column does not exist (see exists(String)

makeColumnValueSelector

public ColumnValueSelector<?> makeColumnValueSelector(String columnName,
 ColumnSelectorFactory selectorFactory,
 @Nullable
 ColumnSelector columnSelector,
 @Nullable
 ReadableOffset offset)

Create a column value selector.

Parameters:

columnName - name the column was referenced with, which is useful if this column uses dot notation.

selectorFactory - object for fetching underlying selectors.

columnSelector - object for fetching underlying columns, if available.

offset - offset to use with underlying columns. Must be provided if columnSelector is provided.

Throws:

IllegalArgumentException - if the virtual column does not exist (see exists(String)

canVectorize

public boolean canVectorize(ColumnInspector columnInspector)

makeSingleValueDimensionVectorSelector

public SingleValueDimensionVectorSelector makeSingleValueDimensionVectorSelector(DimensionSpec dimensionSpec,
 VectorColumnSelectorFactory factory,
 ColumnSelector columnSelector,
 ReadableVectorOffset offset)

Create a single value dimension vector (string) selector.

Parameters:

dimensionSpec - spec the column was referenced with

factory - object for fetching underlying selectors

columnSelector - object for fetching underlying columns

offset - offset to use with underlying columns

Throws:

IllegalArgumentException - if the virtual column does not exist (see exists(String)

makeMultiValueDimensionVectorSelector

public MultiValueDimensionVectorSelector makeMultiValueDimensionVectorSelector(DimensionSpec dimensionSpec,
 VectorColumnSelectorFactory factory,
 ColumnSelector columnSelector,
 ReadableVectorOffset offset)

Create a multi value dimension vector (string) selector.

Parameters:

dimensionSpec - spec the column was referenced with

factory - object for fetching underlying selectors

columnSelector - object for fetching underlying columns

offset - offset to use with underlying columns

Throws:

IllegalArgumentException - if the virtual column does not exist (see exists(String)

makeVectorValueSelector

public VectorValueSelector makeVectorValueSelector(String columnName,
 VectorColumnSelectorFactory factory,
 ColumnSelector columnSelector,
 ReadableVectorOffset offset)

Create a column vector value selector.

Parameters:

columnName - name the column was referenced with

factory - object for fetching underlying selectors

columnSelector - object for fetching underlying columns

offset - offset to use with underlying columns

Throws:

IllegalArgumentException - if the virtual column does not exist (see exists(String)

makeVectorObjectSelector

public VectorObjectSelector makeVectorObjectSelector(String columnName,
 VectorColumnSelectorFactory factory,
 ColumnSelector columnSelector,
 ReadableVectorOffset offset)

Create a column vector object selector.

Parameters:

columnName - name the column was referenced with

factory - object for fetching underlying selectors

columnSelector - object for fetching underlying columns

offset - offset to use with underlying columns

Throws:

IllegalArgumentException - if the virtual column does not exist (see exists(String)

getColumnCapabilitiesWithFallback

@Nullable
public ColumnCapabilities getColumnCapabilitiesWithFallback(ColumnInspector inspector,
 String columnName)

Get capabilities for the column "columnName". If columnName is not a virtual column, delegates to the provided ColumnInspector.

getVirtualColumns

public VirtualColumn[] getVirtualColumns()

wrap

public ColumnSelectorFactory wrap(ColumnSelectorFactory baseFactory)

Creates a VirtualizedColumnSelectorFactory which can create column selectors for virtualColumns in addition to selectors for all physical columns in the underlying factory.

wrapInspector

public ColumnInspector wrapInspector(ColumnInspector inspector)

Creates a VirtualizedColumnInspector that provides ColumnCapabilities information for all virtualColumns in addition to the capabilities of all physical columns in the underlying inspector.

getCacheKey

public byte[] getCacheKey()

Description copied from interface: Cacheable

Get a byte array used as a cache key.

Specified by:

getCacheKey in interface Cacheable

Returns:

bytes to be used as cache key - or null if this object should not be cached.

isEmpty

public boolean isEmpty()

getColumnNames

public List<String> getColumnNames()

equals

public boolean equals(Object o)

Overrides:

equals in class Object

hashCode

public int hashCode()

Overrides:

hashCode in class Object

toString

public String toString()

Overrides:

toString in class Object