java.lang.Object
- org.apache.druid.segment.virtual.NestedFieldVirtualColumn

All Implemented Interfaces:

Cacheable, VirtualColumn
```
public class NestedFieldVirtualColumn
extends Object
implements VirtualColumn
```
Optimized virtual column that can make direct selectors into a NestedDataComplexColumn or any associated nested fields (NestedFieldDictionaryEncodedColumn) including using their indexes.
This virtual column is used for the SQL operators JSON_VALUE (if processFromRaw is set to false) or JSON_QUERY (if it is true), and accepts 'JSONPath' or 'jq' syntax string representations of paths, or a parsed list of NestedPathPart in order to determine what should be selected from the column.
Type information for nested fields is completely absent in the SQL planner, so it guesses the best it can to set expectedType from the context of how something is being used, e.g. an aggregators default type or an explicit cast, or, if using the 'RETURNING' syntax which explicitly specifies type. This might not be the same as if it had actual type information, but, we try to stick with whatever we chose there to do the best we can for now.
Since capabilities(ColumnInspector, String) is determined by the expectedType, the results will be best effor cast to the expected type if the column is not natively the expected type so that this column can fulfill the contract of the type of selector that is likely to be created to read this column.

Nested Class Summary

Nested Classes
Modifier and Type	Class	Description
`static class`	`NestedFieldVirtualColumn.FieldDimensionSelector`
`static class`	`NestedFieldVirtualColumn.RawFieldColumnSelector`	Process the "raw" data to extract values with `NestedPathFinder.find(Object, List)`, wrapping the result in `StructuredData`
`static class`	`NestedFieldVirtualColumn.RawFieldLiteralColumnValueSelector`	Process the "raw" data to extract non-complex values.
`static class`	`NestedFieldVirtualColumn.RawFieldVectorObjectSelector`	Process the "raw" data to extract vectors of values with `NestedPathFinder.find(Object, List)`, wrapping the result in `StructuredData`

Constructor Summary

Constructors
Constructor	Description
`NestedFieldVirtualColumn(String columnName, String path, String outputName)`
`NestedFieldVirtualColumn(String columnName, String path, String outputName, ColumnType expectedType)`
`NestedFieldVirtualColumn(String columnName, String outputName, ColumnType expectedType, List<NestedPathPart> parts, Boolean processFromRaw, String path, Boolean useJqSyntax)`

Method Summary

All Methods Instance Methods Concrete Methods
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.
`String`	`getColumnName()`
`ColumnType`	`getExpectedType()`
`ColumnIndexSupplier`	`getIndexSupplier(String columnName, ColumnSelector selector)`	Get the `ColumnIndexSupplier` for the specified virtual column, with the assistance of a `ColumnSelector` to allow reading things from segments.
`String`	`getOutputName()`	Output name of this column.
`List<NestedPathPart>`	`getPathParts()`
`int`	`hashCode()`
`boolean`	`isProcessFromRaw()`
`ColumnValueSelector<?>`	`makeColumnValueSelector(String columnName, ColumnSelectorFactory factory)`	Build a `ColumnValueSelector` corresponding to this virtual column.
`ColumnValueSelector<?>`	`makeColumnValueSelector(String columnName, ColumnSelector columnSelector, ReadableOffset offset)`	Returns similar `ColumnValueSelector` object as returned by `VirtualColumn.makeColumnValueSelector(String, ColumnSelectorFactory)` except this method has full access to the underlying column and can potentially provide a more efficient implementation.
`DimensionSelector`	`makeDimensionSelector(DimensionSpec dimensionSpec, ColumnSelectorFactory factory)`	Build a selector corresponding to this virtual column.
`DimensionSelector`	`makeDimensionSelector(DimensionSpec dimensionSpec, ColumnSelector columnSelector, ReadableOffset offset)`	Returns similar `DimensionSelector` object as returned by `VirtualColumn.makeDimensionSelector(DimensionSpec, ColumnSelectorFactory)` except this method has full access to the underlying column and can potentially provide a more efficient implementation.
`SingleValueDimensionVectorSelector`	`makeSingleValueVectorDimensionSelector(DimensionSpec dimensionSpec, ColumnSelector columnSelector, ReadableVectorOffset offset)`	Returns similar `SingleValueDimensionVectorSelector` object as returned by `VirtualColumn.makeSingleValueVectorDimensionSelector(DimensionSpec, ColumnSelector, ReadableVectorOffset)` except this method has full access to the underlying column and can potentially provide a more efficient implementation.
`VectorObjectSelector`	`makeVectorObjectSelector(String columnName, ColumnSelector columnSelector, ReadableVectorOffset offset)`	Returns similar `VectorObjectSelector` object as returned by `VirtualColumn.makeVectorObjectSelector(String, VectorColumnSelectorFactory)` except this method has full access to the underlying column and can potentially provide a more efficient implementation.
`VectorValueSelector`	`makeVectorValueSelector(String columnName, ColumnSelector columnSelector, ReadableVectorOffset offset)`	Returns similar `VectorValueSelector` object as returned by `VirtualColumn.makeVectorValueSelector(String, VectorColumnSelectorFactory)` except this method has full access to the underlying column and can potentially provide a more efficient implementation.
`List<String>`	`requiredColumns()`	Returns a list of columns that this virtual column will access.
`String`	`toString()`
`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, wait, wait, wait

Methods inherited from interface org.apache.druid.segment.VirtualColumn
makeMultiValueVectorDimensionSelector, makeMultiValueVectorDimensionSelector, makeSingleValueVectorDimensionSelector, makeVectorObjectSelector, makeVectorValueSelector

- Constructor Detail
  - NestedFieldVirtualColumn
```
public NestedFieldVirtualColumn(String columnName,
                                String outputName,
                                @Nullable
                                ColumnType expectedType,
                                @Nullable
                                List<NestedPathPart> parts,
                                @Nullable
                                Boolean processFromRaw,
                                @Nullable
                                String path,
                                @Nullable
                                Boolean useJqSyntax)
```
  - NestedFieldVirtualColumn
```
public NestedFieldVirtualColumn(String columnName,
                                String path,
                                String outputName)
```
  - NestedFieldVirtualColumn
```
public NestedFieldVirtualColumn(String columnName,
                                String path,
                                String outputName,
                                @Nullable
                                ColumnType expectedType)
```
- Method Detail
  - 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
  - getOutputName
```
public String getOutputName()
```
    Description copied from interface: VirtualColumn
    
    Output name of this column.
    
    Specified by:
    
    getOutputName in interface VirtualColumn
    
    Returns:
    
    name
  - getColumnName
```
public String getColumnName()
```
  - getPathParts
```
public List<NestedPathPart> getPathParts()
```
  - getExpectedType
```
public ColumnType getExpectedType()
```
  - isProcessFromRaw
```
public boolean isProcessFromRaw()
```
  - makeDimensionSelector
```
public DimensionSelector makeDimensionSelector(DimensionSpec dimensionSpec,
                                               ColumnSelectorFactory factory)
```
    Description copied from interface: VirtualColumn
    
    Build a selector corresponding to this virtual column. Also provides the name that the virtual column was referenced with (through DimensionSpec.getDimension(), which is useful if this column uses dot notation. The virtual column is expected to apply any necessary decoration from the dimensionSpec.
    
    Specified by:
    
    makeDimensionSelector in interface VirtualColumn
  - makeColumnValueSelector
```
public ColumnValueSelector<?> makeColumnValueSelector(String columnName,
                                                      ColumnSelectorFactory factory)
```
    Description copied from interface: VirtualColumn
    
    Build a ColumnValueSelector corresponding to this virtual column. Also provides the name that the virtual column was referenced with, which is useful if this column uses dot notation.
    
    Specified by:
    
    makeColumnValueSelector in interface VirtualColumn
  - makeDimensionSelector
```
@Nullable
public DimensionSelector makeDimensionSelector(DimensionSpec dimensionSpec,
                                               ColumnSelector columnSelector,
                                               ReadableOffset offset)
```
    Description copied from interface: VirtualColumn
    
    Returns similar DimensionSelector object as returned by VirtualColumn.makeDimensionSelector(DimensionSpec, ColumnSelectorFactory) except this method has full access to the underlying column and can potentially provide a more efficient implementation. Users of this interface must ensure to first call this method whenever possible. Typically this can not be called in query paths on top of IncrementalIndex which doesn't have columns as in persisted segments.
    
    Specified by:
    
    makeDimensionSelector in interface VirtualColumn
  - makeColumnValueSelector
```
@Nullable
public ColumnValueSelector<?> makeColumnValueSelector(String columnName,
                                                      ColumnSelector columnSelector,
                                                      ReadableOffset offset)
```
    Description copied from interface: VirtualColumn
    
    Returns similar ColumnValueSelector object as returned by VirtualColumn.makeColumnValueSelector(String, ColumnSelectorFactory) except this method has full access to the underlying column and can potentially provide a more efficient implementation. Users of this interface must ensure to first call this method whenever possible. Typically this can not be called in query paths on top of IncrementalIndex which doesn't have columns as in persisted segments.
    
    Specified by:
    
    makeColumnValueSelector in interface VirtualColumn
  - canVectorize
```
public boolean canVectorize(ColumnInspector inspector)
```
    Specified by:
    
    canVectorize in interface VirtualColumn
  - makeSingleValueVectorDimensionSelector
```
@Nullable
public SingleValueDimensionVectorSelector makeSingleValueVectorDimensionSelector(DimensionSpec dimensionSpec,
                                                                                 ColumnSelector columnSelector,
                                                                                 ReadableVectorOffset offset)
```
    Description copied from interface: VirtualColumn
    
    Returns similar SingleValueDimensionVectorSelector object as returned by VirtualColumn.makeSingleValueVectorDimensionSelector(DimensionSpec, ColumnSelector, ReadableVectorOffset) except this method has full access to the underlying column and can potentially provide a more efficient implementation. Users of this interface must ensure to first call this method whenever possible.
    
    Specified by:
    
    makeSingleValueVectorDimensionSelector in interface VirtualColumn
  - makeVectorObjectSelector
```
@Nullable
public VectorObjectSelector makeVectorObjectSelector(String columnName,
                                                     ColumnSelector columnSelector,
                                                     ReadableVectorOffset offset)
```
    Description copied from interface: VirtualColumn
    
    Returns similar VectorObjectSelector object as returned by VirtualColumn.makeVectorObjectSelector(String, VectorColumnSelectorFactory) except this method has full access to the underlying column and can potentially provide a more efficient implementation. Users of this interface must ensure to first call this method whenever possible.
    
    Specified by:
    
    makeVectorObjectSelector in interface VirtualColumn
  - makeVectorValueSelector
```
@Nullable
public VectorValueSelector makeVectorValueSelector(String columnName,
                                                   ColumnSelector columnSelector,
                                                   ReadableVectorOffset offset)
```
    Description copied from interface: VirtualColumn
    
    Returns similar VectorValueSelector object as returned by VirtualColumn.makeVectorValueSelector(String, VectorColumnSelectorFactory) except this method has full access to the underlying column and can potentially provide a more efficient implementation. Users of this interface must ensure to first call this method whenever possible.
    
    Specified by:
    
    makeVectorValueSelector in interface VirtualColumn
  - getIndexSupplier
```
@Nullable
public ColumnIndexSupplier getIndexSupplier(String columnName,
                                            ColumnSelector selector)
```
    Description copied from interface: VirtualColumn
    
    Get the ColumnIndexSupplier for the specified virtual column, with the assistance of a ColumnSelector to allow reading things from segments. If the virtual column has no indexes, this method will return null, or may also return a non-null supplier whose methods may return null values - having a supplier is no guarantee that the column has indexes.
    
    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, must not be null
  - 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
  - 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

Class NestedFieldVirtualColumn

Nested Class Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

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

Constructor Detail

NestedFieldVirtualColumn

NestedFieldVirtualColumn

NestedFieldVirtualColumn

Method Detail

getCacheKey

getOutputName

getColumnName

getPathParts

getExpectedType

isProcessFromRaw

makeDimensionSelector

makeColumnValueSelector

makeDimensionSelector

makeColumnValueSelector

canVectorize

makeSingleValueVectorDimensionSelector

makeVectorObjectSelector

makeVectorValueSelector

getIndexSupplier

capabilities

capabilities

requiredColumns

usesDotNotation

equals

hashCode

toString