Package org.apache.lucene.search

# Class SortField

java.lang.Object
org.apache.lucene.search.SortField

Direct Known Subclasses:
  `SortedNumericSortField`, `SortedSetSortField`

public class SortField extends Object
Stores information about how to sort documents by terms in an individual field. Fields must be indexed in order to sort by them.

Sorting on a numeric field that is indexed with both doc values and points may use an optimization to skip non-competitive documents. This optimization relies on the assumption that the same data is stored in these points and doc values.

Sorting on a SORTED(_SET) field that is indexed with both doc values and term index may use an optimization to skip non-competitive documents. This optimization relies on the assumption that the same data is stored in these term index and doc values.

Created: Feb 11, 2004 1:25:29 PM

Since:
  lucene 1.4
See Also:
  - `Sort`

- ## Nested Class Summary

  Nested Classes
  Modifier and Type
  Class
  Description
  `static final class`
  `SortField.Provider`
  A SortFieldProvider for field sorts
  `static enum`
  `SortField.Type`
  Specifies the type of the terms to be sorted, or special types such as CUSTOM

- ## Field Summary

  Fields
  Modifier and Type
  Field
  Description
  `static final SortField`
  `FIELD_DOC`
  Represents sorting by document number (index order).
  `static final SortField`
  `FIELD_SCORE`
  Represents sorting by document score (relevance).
  `protected Object`
  `missingValue`
  `static final Object`
  `STRING_FIRST`
  Pass this to `setMissingValue(java.lang.Object)` to have missing string values sort first.
  `static final Object`
  `STRING_LAST`
  Pass this to `setMissingValue(java.lang.Object)` to have missing string values sort last.

- ## Constructor Summary

  Constructors
  Constructor
  Description
  `SortField(String field, FieldComparatorSource comparator)`
  Creates a sort with a custom comparison function.
  `SortField(String field, FieldComparatorSource comparator, boolean reverse)`
  Creates a sort, possibly in reverse, with a custom comparison function.
  `SortField(String field, SortField.Type type)`
  Creates a sort by terms in the given field with the type of term values explicitly given.
  `SortField(String field, SortField.Type type, boolean reverse)`
  Creates a sort, possibly in reverse, by terms in the given field with the type of term values explicitly given.

- ## Method Summary

  Modifier and Type
  Method
  Description
  `boolean`
  `equals(Object o)`
  Returns true if `o` is equal to this.
  `Comparator<BytesRef>`
  `getBytesComparator()`
  `FieldComparator<?>`
  `getComparator(int numHits, Pruning pruning)`
  Returns the `FieldComparator` to use for sorting.
  `FieldComparatorSource`
  `getComparatorSource()`
  Returns the `FieldComparatorSource` used for custom sorting
  `String`
  `getField()`
  Returns the name of the field.
  `IndexSorter`
  `getIndexSorter()`
  Returns an `IndexSorter` used for sorting index segments by this SortField.
  `Object`
  `getMissingValue()`
  Return the value to use for documents that don't have a value.
  `boolean`
  `getOptimizeSortWithIndexedData()`
  Deprecated.
  `boolean`
  `getOptimizeSortWithPoints()`
  Deprecated.
  This is a duplicate method for `SortField#getOptimizeSortWithIndexedData`.
  `boolean`
  `getReverse()`
  Returns whether the sort should be reversed.
  `SortField.Type`
  `getType()`
  Returns the type of contents in the field.
  `int`
  `hashCode()`
  Returns a hash code for this `SortField` instance.
  `boolean`
  `needsScores()`
  Whether the relevance score is needed to sort documents.
  `protected static SortField.Type`
  `readType(DataInput in)`
  `SortField`
  `rewrite(IndexSearcher searcher)`
  Rewrites this SortField, returning a new SortField if a change is made.
  `void`
  `setBytesComparator(Comparator<BytesRef> b)`
  `void`
  `setMissingValue(Object missingValue)`
  Set the value to use for documents that don't have a value.
  `void`
  `setOptimizeSortWithIndexedData(boolean optimizeSortWithIndexedData)`
  Deprecated.
  should only be used for compatibility with 8.x indices that got created with inconsistent data across fields, or the wrong sort configuration in the index sort
  `void`
  `setOptimizeSortWithPoints(boolean optimizeSortWithPoints)`
  Deprecated.
  should only be used for compatibility with 8.x indices that got created with inconsistent data across fields, or the wrong sort configuration in the index sort.
  `String`
  `toString()`

  ### Methods inherited from class java.lang.Object

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

- ## Field Details

  - ### FIELD_SCORE

    public static final SortField FIELD_SCORE
    Represents sorting by document score (relevance).

  - ### FIELD_DOC

    public static final SortField FIELD_DOC
    Represents sorting by document number (index order).

  - ### missingValue

    protected Object missingValue

  - ### STRING_FIRST

    public static final Object STRING_FIRST
    Pass this to `setMissingValue(java.lang.Object)` to have missing string values sort first.

  - ### STRING_LAST

    public static final Object STRING_LAST
    Pass this to `setMissingValue(java.lang.Object)` to have missing string values sort last.

- ## Constructor Details

  - ### SortField

    public SortField(String field, SortField.Type type)
    Creates a sort by terms in the given field with the type of term values explicitly given.
    Parameters:
      `field` - Name of field to sort by. Can be `null` if `type` is SCORE or DOC.
      `type` - Type of values in the terms.

  - ### SortField

    public SortField(String field, SortField.Type type, boolean reverse)
    Creates a sort, possibly in reverse, by terms in the given field with the type of term values explicitly given.
    Parameters:
      `field` - Name of field to sort by. Can be `null` if `type` is SCORE or DOC.
      `type` - Type of values in the terms.
      `reverse` - True if natural order should be reversed.

  - ### SortField

    public SortField(String field, FieldComparatorSource comparator)
    Creates a sort with a custom comparison function.
    Parameters:
      `field` - Name of field to sort by; cannot be `null`.
      `comparator` - Returns a comparator for sorting hits.

  - ### SortField

    public SortField(String field, FieldComparatorSource comparator, boolean reverse)
    Creates a sort, possibly in reverse, with a custom comparison function.
    Parameters:
      `field` - Name of field to sort by; cannot be `null`.
      `comparator` - Returns a comparator for sorting hits.
      `reverse` - True if natural order should be reversed.

- ## Method Details

  - ### readType

    protected static SortField.Type readType(DataInput in) throws IOException
    Throws:
      `IOException`

  - ### getMissingValue

    public Object getMissingValue()
    Return the value to use for documents that don't have a value. A value of `null` indicates that default should be used.

  - ### setMissingValue

    public void setMissingValue(Object missingValue)
    Set the value to use for documents that don't have a value.

  - ### getField

    public String getField()
    Returns the name of the field. Could return `null` if the sort is by SCORE or DOC.
    Returns:
      Name of field, possibly `null`.

  - ### getType

    public SortField.Type getType()
    Returns the type of contents in the field.
    Returns:
      One of the constants SCORE, DOC, STRING, INT or FLOAT.

  - ### getReverse

    public boolean getReverse()
    Returns whether the sort should be reversed.
    Returns:
      True if natural order should be reversed.

  - ### getComparatorSource

    public FieldComparatorSource getComparatorSource()
    Returns the `FieldComparatorSource` used for custom sorting

  - ### toString

    public String toString()
    Overrides:
      `toString` in class `Object`

  - ### equals

    public boolean equals(Object o)
    Returns true if `o` is equal to this. If a `FieldComparatorSource` was provided, it must properly implement equals (unless a singleton is always used).
    Overrides:
      `equals` in class `Object`

  - ### hashCode

    public int hashCode()
    Returns a hash code for this `SortField` instance. If a `FieldComparatorSource` was provided, it must properly implement hashCode (unless a singleton is always used).
    Overrides:
      `hashCode` in class `Object`

  - ### setBytesComparator

    public void setBytesComparator(Comparator<BytesRef> b)

  - ### getBytesComparator

    public Comparator<BytesRef> getBytesComparator()

  - ### getComparator

    public FieldComparator<?> getComparator(int numHits, Pruning pruning)
    Returns the `FieldComparator` to use for sorting.
    Parameters:
      `numHits` - number of top hits the queue will store
      `pruning` - controls how can the comparator to skip documents via `LeafFieldComparator.competitiveIterator()`
    Returns:
      `FieldComparator` to use when sorting
    WARNING: This API is experimental and might change in incompatible ways in the next release.

  - ### rewrite

    public SortField rewrite(IndexSearcher searcher) throws IOException
    Rewrites this SortField, returning a new SortField if a change is made. Subclasses should override this define their rewriting behavior when this SortField is of type `SortField.Type.REWRITEABLE`
    Parameters:
      `searcher` - IndexSearcher to use during rewriting
    Returns:
      New rewritten SortField, or `this` if nothing has changed.
    Throws:
      `IOException` - Can be thrown by the rewriting
    WARNING: This API is experimental and might change in incompatible ways in the next release.

  - ### needsScores

    public boolean needsScores()
    Whether the relevance score is needed to sort documents.

  - ### getIndexSorter

    public IndexSorter getIndexSorter()
    Returns an `IndexSorter` used for sorting index segments by this SortField.

    If the SortField cannot be used for index sorting (for example, if it uses scores or other query-dependent values) then this method should return `null`

    SortFields that implement this method should also implement a companion `SortFieldProvider` to serialize and deserialize the sort in index segment headers

    WARNING: This API is experimental and might change in incompatible ways in the next release.

  - ### setOptimizeSortWithIndexedData

    @Deprecated public void setOptimizeSortWithIndexedData(boolean optimizeSortWithIndexedData)
    Deprecated.
    should only be used for compatibility with 8.x indices that got created with inconsistent data across fields, or the wrong sort configuration in the index sort
    Enables/disables numeric sort optimization to use the indexed data.

    Enabled by default. By default, sorting on a numeric field activates point sort optimization that can efficiently skip over non-competitive hits. Sort optimization has a number of requirements, one of which is that SortField.Type matches the Point type with which the field was indexed (e.g. sort on IntPoint field should use SortField.Type.INT). Another requirement is that the same data is indexed with points and doc values for the field.

    By default, sorting on a SORTED(_SET) field activates sort optimization that can efficiently skip over non-competitive hits. Sort optimization requires that the same data is indexed with term index and doc values for the field.

    Parameters:
      `optimizeSortWithIndexedData` - providing `false` disables the optimization, in cases where these requirements can't be met.

  - ### getOptimizeSortWithIndexedData

    @Deprecated public boolean getOptimizeSortWithIndexedData()
    Deprecated.
    Returns whether sort optimization should be optimized with indexed data
    Returns:
      whether sort optimization should be optimized with indexed data

  - ### setOptimizeSortWithPoints

    @Deprecated public void setOptimizeSortWithPoints(boolean optimizeSortWithPoints)
    Deprecated.
    should only be used for compatibility with 8.x indices that got created with inconsistent data across fields, or the wrong sort configuration in the index sort. This is a duplicate method for `SortField#setOptimizeSortWithIndexedData`.
    Enables/disables numeric sort optimization to use the Points index.

    Enabled by default. By default, sorting on a numeric field activates point sort optimization that can efficiently skip over non-competitive hits. Sort optimization has a number of requirements, one of which is that SortField.Type matches the Point type with which the field was indexed (e.g. sort on IntPoint field should use SortField.Type.INT). Another requirement is that the same data is indexed with points and doc values for the field.

    Parameters:
      `optimizeSortWithPoints` - providing `false` disables the optimization, in cases where these requirements can't be met.

  - ### getOptimizeSortWithPoints

    @Deprecated public boolean getOptimizeSortWithPoints()
    Deprecated.
    This is a duplicate method for `SortField#getOptimizeSortWithIndexedData`.
    Returns whether sort optimization should be optimized with points index
    Returns:
      whether sort optimization should be optimized with points index