io.druid.segment

Class VirtualColumns

java.lang.Object

io.druid.segment.VirtualColumns

All Implemented Interfaces:

Cacheable

public class VirtualColumns
extends Object
implements Cacheable

Class allowing lookup and usage of virtual columns.

Field Summary

Fields

Modifier and Type	Field and Description
static VirtualColumns	EMPTY

Method Summary

Modifier and Type	Method and Description
static VirtualColumns	create(List<VirtualColumn> virtualColumns)
boolean	equals(Object o)
boolean	exists(String columnName) Returns true if a virtual column exists with a particular columnName.
byte[]	getCacheKey() Get a byte array used as a cache key.
ColumnCapabilities	getColumnCapabilities(String columnName)
ColumnCapabilities	getColumnCapabilitiesWithFallback(StorageAdapter adapter, String columnName)
VirtualColumn	getVirtualColumn(String columnName)
VirtualColumn[]	getVirtualColumns()
int	hashCode()
ColumnValueSelector<?>	makeColumnValueSelector(String columnName, ColumnSelectorFactory factory) Create a column value selector.
DimensionSelector	makeDimensionSelector(DimensionSpec dimensionSpec, ColumnSelectorFactory factory) Create a dimension (string) 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)

Methods inherited from class java.lang.Object

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

Field Detail

EMPTY

public static final VirtualColumns EMPTY

Method Detail

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(List<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

public VirtualColumn getVirtualColumn(String columnName)

makeDimensionSelector

public DimensionSelector makeDimensionSelector(DimensionSpec dimensionSpec,
                                               ColumnSelectorFactory factory)

Create a dimension (string) selector.

Parameters:

dimensionSpec - the dimensionSpec for this selector

factory - base column selector factory

Returns:

selector

Throws:

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

makeColumnValueSelector

public ColumnValueSelector<?> makeColumnValueSelector(String columnName,
                                                      ColumnSelectorFactory factory)

Create a column value selector.

Parameters:

columnName - column mame

factory - base column selector factory

Returns:

selector

Throws:

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

getColumnCapabilities

public ColumnCapabilities getColumnCapabilities(String columnName)

getColumnCapabilitiesWithFallback

public ColumnCapabilities getColumnCapabilitiesWithFallback(StorageAdapter adapter,
                                                            String columnName)

getVirtualColumns

public VirtualColumn[] getVirtualColumns()

wrap

public ColumnSelectorFactory wrap(ColumnSelectorFactory baseFactory)

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:

a cache key

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