Package org.apache.druid.segment.virtual

Class SpecializedExpressionVirtualColumn

java.lang.Object

org.apache.druid.segment.virtual.SpecializedExpressionVirtualColumn

All Implemented Interfaces:

Cacheable, VirtualColumn

Direct Known Subclasses:

NestedMergeVirtualColumn, NestedObjectVirtualColumn

public abstract class SpecializedExpressionVirtualColumn
extends Object
implements VirtualColumn

Base class for virtual columns that are specialized implementations of expressions. All methods delegate to ExpressionVirtualColumn. Subclasses may override individual methods with more optimized versions.

Nested Class Summary

Nested classes/interfaces inherited from interface org.apache.druid.segment.VirtualColumn

VirtualColumn.EquivalenceKey

Field Summary

Fields

Modifier and Type	Field	Description
protected final ExpressionVirtualColumn	delegate

Constructor Summary

Constructors

Constructor	Description
SpecializedExpressionVirtualColumn(ExpressionVirtualColumn delegate)

Method Summary

Modifier and Type	Method	Description
boolean	canVectorize(ColumnInspector inspector)
ColumnCapabilities	capabilities(String columnName)	This method is deprecated in favor of VirtualColumn.capabilities(ColumnInspector, String), which should be used whenever possible and can support virtual column implementations that need to inspect other columns as inputs.
ColumnCapabilities	capabilities(ColumnInspector inspector, String columnName)	Return the ColumnCapabilities which best describe the optimal selector to read from this virtual column.
boolean	equals(Object o)
byte[]	getCacheKey()	Get a byte array used as a cache key.
VirtualColumn.EquivalenceKey	getEquivalanceKey()	Returns a key used for "equivalence" comparisons, for checking if some virtual column is equivalent to some other virtual column, regardless of the output name.
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.
String	getOutputName()	Output name of this column.
int	hashCode()
ColumnValueSelector<?>	makeColumnValueSelector(String columnName, ColumnSelectorFactory columnSelectorFactory, ColumnSelector columnSelector, ReadableOffset offset)	Builds a selector corresponding to this virtual column.
DimensionSelector	makeDimensionSelector(DimensionSpec dimensionSpec, ColumnSelectorFactory columnSelectorFactory, ColumnSelector columnSelector, ReadableOffset offset)	Build a selector corresponding to this virtual column.
GroupByVectorColumnSelector	makeGroupByVectorColumnSelector(String columnName, VectorColumnSelectorFactory factory, DeferExpressionDimensions deferExpressionDimensions)	Returns a group-by selector.
MultiValueDimensionVectorSelector	makeMultiValueVectorDimensionSelector(DimensionSpec dimensionSpec, VectorColumnSelectorFactory factory, ColumnSelector columnSelector, ReadableVectorOffset offset)	Build a selector corresponding to this virtual column.
SingleValueDimensionVectorSelector	makeSingleValueVectorDimensionSelector(DimensionSpec dimensionSpec, VectorColumnSelectorFactory factory, ColumnSelector columnSelector, ReadableVectorOffset offset)	Build a selector corresponding to this virtual column.
VectorObjectSelector	makeVectorObjectSelector(String columnName, VectorColumnSelectorFactory factory, ColumnSelector columnSelector, ReadableVectorOffset offset)	Build a selector corresponding to this virtual column.
VectorValueSelector	makeVectorValueSelector(String columnName, VectorColumnSelectorFactory factory, ColumnSelector columnSelector, ReadableVectorOffset offset)	Build a selector corresponding to this virtual column.
List<String>	requiredColumns()	Returns a list of columns that this virtual column will access.
SelectableColumn	toSelectableColumn(ColumnIndexSelector columnSelector)	Produces a SelectableColumn from this virtual column.
boolean	usesDotNotation()	Indicates that this virtual column can be referenced with dot notation.

Methods inherited from class java.lang.Object

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

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

makeColumnValueSelector, makeColumnValueSelector, makeDimensionSelector, makeDimensionSelector, makeMultiValueVectorDimensionSelector, makeMultiValueVectorDimensionSelector, makeSingleValueVectorDimensionSelector, makeSingleValueVectorDimensionSelector, makeVectorObjectSelector, makeVectorObjectSelector, makeVectorValueSelector, makeVectorValueSelector, rewriteRequiredColumns, supportsRequiredRewrite

Field Details

delegate

protected final ExpressionVirtualColumn delegate

Constructor Details

SpecializedExpressionVirtualColumn

public SpecializedExpressionVirtualColumn(ExpressionVirtualColumn delegate)

Method Details

getOutputName

public String getOutputName()

Description copied from interface: VirtualColumn

Output name of this column.

Specified by:

getOutputName in interface VirtualColumn

Returns:

name

canVectorize

public boolean canVectorize(ColumnInspector inspector)

Specified by:

canVectorize in interface VirtualColumn

makeDimensionSelector

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

Description copied from interface: VirtualColumn

Build a selector corresponding to this virtual column. The virtual column is expected to apply any necessary DimensionSpec.decorate(DimensionSelector) or DimensionSpec.getExtractionFn() from the dimensionSpec.

Specified by:

makeDimensionSelector in interface VirtualColumn

Parameters:

dimensionSpec - spec the column was referenced with. Also provides the name that the virtual column was referenced with, which is useful if this column uses dot notation.

columnSelectorFactory - object for fetching underlying selectors.

columnSelector - object for fetching underlying columns, if available. Generally only available for regular segments.

offset - offset to use with underlying columns. Available only if columnSelector is available.

makeColumnValueSelector

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

Description copied from interface: VirtualColumn

Builds a selector corresponding to this virtual column.

Specified by:

makeColumnValueSelector in interface VirtualColumn

Parameters:

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

columnSelectorFactory - object for fetching underlying selectors.

columnSelector - object for fetching underlying columns, if available. Generally only available for regular segments.

offset - offset to use with underlying columns. Available only if columnSelector is available.

makeSingleValueVectorDimensionSelector

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

Description copied from interface: VirtualColumn

Build a selector corresponding to this virtual column. The virtual column is expected to apply any necessary DimensionSpec.decorate(DimensionSelector) or DimensionSpec.getExtractionFn() from the dimensionSpec.

Specified by:

makeSingleValueVectorDimensionSelector in interface VirtualColumn

Parameters:

dimensionSpec - spec the column was referenced with. Also provides the name that the virtual column was referenced with, which is useful if this column uses dot notation.

factory - object for fetching underlying selectors.

columnSelector - object for fetching underlying columns.

offset - offset to use with underlying columns.

makeMultiValueVectorDimensionSelector

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

Description copied from interface: VirtualColumn

Build a selector corresponding to this virtual column. The virtual column is expected to apply any necessary DimensionSpec.decorate(DimensionSelector) or DimensionSpec.getExtractionFn() from the dimensionSpec.

Specified by:

makeMultiValueVectorDimensionSelector in interface VirtualColumn

Parameters:

dimensionSpec - spec the column was referenced with. Also provides the name that the virtual column was referenced with, which is useful if this column uses dot notation.

factory - object for fetching underlying selectors.

columnSelector - object for fetching underlying columns, if available. Generally only available for regular segments.

offset - offset to use with underlying columns. Available only if columnSelector is available.

makeVectorValueSelector

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

Description copied from interface: VirtualColumn

Build a selector corresponding to this virtual column. The virtual column is expected to apply any necessary DimensionSpec.decorate(DimensionSelector) or DimensionSpec.getExtractionFn() from the dimensionSpec.

Specified by:

makeVectorValueSelector in interface VirtualColumn

Parameters:

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

factory - object for fetching underlying selectors.

columnSelector - object for fetching underlying columns.

offset - offset to use with underlying columns.

makeVectorObjectSelector

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

Description copied from interface: VirtualColumn

Build a selector corresponding to this virtual column. The virtual column is expected to apply any necessary DimensionSpec.decorate(DimensionSelector) or DimensionSpec.getExtractionFn() from the dimensionSpec.

Specified by:

makeVectorObjectSelector in interface VirtualColumn

Parameters:

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

factory - object for fetching underlying selectors.

columnSelector - object for fetching underlying columns, if available. Generally only available for regular segments.

offset - offset to use with underlying columns. Available only if columnSelector is available.

makeGroupByVectorColumnSelector

@Nullable
public GroupByVectorColumnSelector makeGroupByVectorColumnSelector(String columnName,
 VectorColumnSelectorFactory factory,
 DeferExpressionDimensions deferExpressionDimensions)

Description copied from interface: VirtualColumn

Returns a group-by selector. Allows virtual columns to control their own grouping behavior.

Specified by:

makeGroupByVectorColumnSelector in interface VirtualColumn

Parameters:

columnName - column name

factory - column selector factory

deferExpressionDimensions - active value of GroupByQueryConfig.CTX_KEY_DEFER_EXPRESSION_DIMENSIONS

Returns:

selector, or null if this virtual column does not have a specialized one

getIndexSupplier

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

Description copied from interface: VirtualColumn

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.

Specified by:

getIndexSupplier in interface VirtualColumn

capabilities

public ColumnCapabilities capabilities(String columnName)

Description copied from interface: VirtualColumn

This method is deprecated in favor of VirtualColumn.capabilities(ColumnInspector, String), which should be used whenever possible and can support virtual column implementations that need to inspect other columns as inputs. This is a fallback implementation to return the capabilities of this virtual column, which includes a type that corresponds to the best performing base selector supertype (e. g. BaseLongColumnValueSelector) of the object, returned from VirtualColumn.makeColumnValueSelector(String, ColumnSelectorFactory). May vary based on columnName if this column uses dot notation.

Specified by:

capabilities in interface VirtualColumn

Parameters:

columnName - the name this virtual column was referenced with

Returns:

capabilities, must not be null

capabilities

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

Description copied from interface: VirtualColumn

Return the ColumnCapabilities which best describe the optimal selector to read from this virtual column.

The ColumnInspector (most likely corresponding to an underlying ColumnSelectorFactory of a query) allows the virtual column to consider this information if necessary to compute its output type details.

Examples of this include the ExpressionVirtualColumn, which takes input from other columns and uses the ColumnInspector to infer the output type of expressions based on the types of the inputs.

Specified by:

capabilities in interface VirtualColumn

Parameters:

inspector - column inspector to provide additional information of other available columns

columnName - the name this virtual column was referenced with

Returns:

capabilities, or null if the column should be treated as if it doesn't exist.

requiredColumns

public List<String> requiredColumns()

Description copied from interface: VirtualColumn

Returns a list of columns that this virtual column will access. This may include the names of other virtual columns. May be empty if a virtual column doesn't access any underlying columns. Does not pass columnName because there is an assumption that the list of columns needed by a dot-notation supporting virtual column will not vary based on the columnName.

Specified by:

requiredColumns in interface VirtualColumn

Returns:

column names

usesDotNotation

public boolean usesDotNotation()

Description copied from interface: VirtualColumn

Indicates that this virtual column can be referenced with dot notation. For example, a virtual column named "foo" could be referred to as "foo.bar" with the Cursor it is registered with. In that case, init will be called with columnName "foo.bar" rather than "foo".

Specified by:

usesDotNotation in interface VirtualColumn

Returns:

whether to use dot notation

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.

getEquivalanceKey

@Nullable
public VirtualColumn.EquivalenceKey getEquivalanceKey()

Description copied from interface: VirtualColumn

Returns a key used for "equivalence" comparisons, for checking if some virtual column is equivalent to some other virtual column, regardless of the output name. If this method returns null, it does not participate in equivalence comparisons.

Specified by:

getEquivalanceKey in interface VirtualColumn

See Also:

• VirtualColumns.findEquivalent(VirtualColumns, VirtualColumn)

toSelectableColumn

public SelectableColumn toSelectableColumn(ColumnIndexSelector columnSelector)

Description copied from interface: VirtualColumn

Produces a SelectableColumn from this virtual column. This allows the virtual column to offer specialized interfaces, such as NestedColumnTypeInspector or NestedColumnSelectorFactory. These interfaces may be used by query objects, including other virtual columns, to perform queries in a more efficient manner.

Specified by:

toSelectableColumn in interface VirtualColumn

Parameters:

columnSelector - selector for underlying columns and indexes. Cannot be used during execution of this method, but can be stored for later usage.

equals

public boolean equals(Object o)

Overrides:

equals in class Object

hashCode

public int hashCode()

Overrides:

hashCode in class Object