Package org.apache.lucene.index

# Class ParallelLeafReader

java.lang.Object
org.apache.lucene.index.IndexReader
org.apache.lucene.index.LeafReader
org.apache.lucene.index.ParallelLeafReader

All Implemented Interfaces:
  `Closeable`, `AutoCloseable`

public class ParallelLeafReader extends LeafReader
An `LeafReader` which reads multiple, parallel indexes. Each index added must have the same number of documents, but typically each contains different fields. Deletions are taken from the first reader. Each document contains the union of the fields of all documents with the same document number. When searching, matches for a query term are from the first index added that has the field.

This is useful, e.g., with collections that have large fields which change rarely and small fields that change more frequently. The smaller fields may be re-indexed in a new index and both indexes may be searched together.

Warning: It is up to you to make sure all indexes are created and modified the same way. For example, if you add documents to one index, you need to add the same documents in the same order to the other indexes. Failure to do so will result in undefined behavior.

## Nested Class Summary

## Nested classes/interfaces inherited from class org.apache.lucene.index.IndexReader

`IndexReader.CacheHelper, IndexReader.CacheKey, IndexReader.ClosedListener`

## Constructor Summary

Constructors
Constructor
Description
`ParallelLeafReader(boolean closeSubReaders, LeafReader... readers)`
Create a ParallelLeafReader based on the provided readers.
`ParallelLeafReader(boolean closeSubReaders, LeafReader[] readers, LeafReader[] storedFieldsReaders)`
Expert: create a ParallelLeafReader based on the provided readers and storedFieldReaders; when a document is loaded, only storedFieldsReaders will be used.
`ParallelLeafReader(LeafReader... readers)`
Create a ParallelLeafReader based on the provided readers; auto-closes the given readers on `IndexReader.close()`.

## Method Summary

Modifier and Type
Method
Description
`void`
`checkIntegrity()`
Checks consistency of this reader.
`protected void`
`doClose()`
Implements close.
`BinaryDocValues`
`getBinaryDocValues(String field)`
Returns `BinaryDocValues` for this field, or null if no binary doc values were indexed for this field.
`ByteVectorValues`
`getByteVectorValues(String fieldName)`
Returns `ByteVectorValues` for this field, or null if no `ByteVectorValues` were indexed.
`IndexReader.CacheHelper`
`getCoreCacheHelper()`
Optional method: Return a `IndexReader.CacheHelper` that can be used to cache based on the content of this leaf regardless of deletions.
`DocValuesSkipper`
`getDocValuesSkipper(String field)`
Returns a `DocValuesSkipper` allowing skipping ranges of doc IDs that are not of interest, or `null` if a skip index was not indexed.
`FieldInfos`
`getFieldInfos()`
Get the `FieldInfos` describing all fields in this reader.
`FloatVectorValues`
`getFloatVectorValues(String fieldName)`
Returns `FloatVectorValues` for this field, or null if no `FloatVectorValues` were indexed.
`Bits`
`getLiveDocs()`
Returns the `Bits` representing live (not deleted) docs.
`LeafMetaData`
`getMetaData()`
Return metadata about this leaf.
`NumericDocValues`
`getNormValues(String field)`
Returns `NumericDocValues` representing norms for this field, or null if no `NumericDocValues` were indexed.
`NumericDocValues`
`getNumericDocValues(String field)`
Returns `NumericDocValues` for this field, or null if no numeric doc values were indexed for this field.
`LeafReader[]`
`getParallelReaders()`
Returns the `LeafReader`s that were passed on init.
`PointValues`
`getPointValues(String fieldName)`
Returns the `PointValues` used for numeric or spatial searches for the given field, or null if there are no point fields.
`IndexReader.CacheHelper`
`getReaderCacheHelper()`
Optional method: Return a `IndexReader.CacheHelper` that can be used to cache based on the content of this reader.
`SortedDocValues`
`getSortedDocValues(String field)`
Returns `SortedDocValues` for this field, or null if no `SortedDocValues` were indexed for this field.
`SortedNumericDocValues`
`getSortedNumericDocValues(String field)`
Returns `SortedNumericDocValues` for this field, or null if no `SortedNumericDocValues` were indexed for this field.
`SortedSetDocValues`
`getSortedSetDocValues(String field)`
Returns `SortedSetDocValues` for this field, or null if no `SortedSetDocValues` were indexed for this field.
`int`
`maxDoc()`
Returns one greater than the largest possible document number.
`int`
`numDocs()`
Returns the number of documents in this index.
`void`
`searchNearestVectors(String fieldName, byte[] target, KnnCollector knnCollector, Bits acceptDocs)`
Return the k nearest neighbor documents as determined by comparison of their vector values for this field, to the given vector, by the field's similarity function.
`void`
`searchNearestVectors(String fieldName, float[] target, KnnCollector knnCollector, Bits acceptDocs)`
Return the k nearest neighbor documents as determined by comparison of their vector values for this field, to the given vector, by the field's similarity function.
`StoredFields`
`storedFields()`
Returns a `StoredFields` reader for the stored fields of this index.
`Terms`
`terms(String field)`
Returns the `Terms` index for this field, or null if it has none.
`TermVectors`
`termVectors()`
Returns a `TermVectors` reader for the term vectors of this index.
`String`
`toString()`

### Methods inherited from class org.apache.lucene.index.LeafReader

`docFreq, getContext, getDocCount, getSumDocFreq, getSumTotalTermFreq, postings, postings, searchNearestVectors, searchNearestVectors, totalTermFreq`

### Methods inherited from class org.apache.lucene.index.IndexReader

`close, decRef, ensureOpen, equals, getRefCount, hasDeletions, hashCode, incRef, leaves, notifyReaderClosedListeners, numDeletedDocs, registerParentReader, tryIncRef`

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

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

## Constructor Details

### ParallelLeafReader

public ParallelLeafReader(LeafReader... readers) throws IOException
Create a ParallelLeafReader based on the provided readers; auto-closes the given readers on `IndexReader.close()`.

Throws:
  `IOException`

### ParallelLeafReader

public ParallelLeafReader(boolean closeSubReaders, LeafReader... readers) throws IOException
Create a ParallelLeafReader based on the provided readers.

Throws:
  `IOException`

### ParallelLeafReader

public ParallelLeafReader(boolean closeSubReaders, LeafReader[] readers, LeafReader[] storedFieldsReaders) throws IOException
Expert: create a ParallelLeafReader based on the provided readers and storedFieldReaders; when a document is loaded, only storedFieldsReaders will be used.

Throws:
  `IOException`

## Method Details

### toString

public String toString()

Overrides:
  `toString` in class `Object`

### getFieldInfos

public FieldInfos getFieldInfos()
Get the `FieldInfos` describing all fields in this reader.

Note: Implementations should cache the FieldInfos instance returned by this method such that subsequent calls to this method return the same instance.

NOTE: the returned field numbers will likely not correspond to the actual field numbers in the underlying readers, and codec metadata (`FieldInfo.getAttribute(String)` will be unavailable.

Specified by:
  `getFieldInfos` in class `LeafReader`

### getLiveDocs

public Bits getLiveDocs()
Description copied from class: `LeafReader`
Returns the `Bits` representing live (not deleted) docs. A set bit indicates the doc ID has not been deleted. If this method returns null it means there are no deleted documents (all documents are live).

The returned instance has been safely published for use by multiple threads without additional synchronization.

Specified by:
  `getLiveDocs` in class `LeafReader`

### terms

public Terms terms(String field) throws IOException
Description copied from class: `LeafReader`
Returns the `Terms` index for this field, or null if it has none.

Specified by:
  `terms` in class `LeafReader`
Throws:
  `IOException`

### numDocs

public int numDocs()
Description copied from class: `IndexReader`
Returns the number of documents in this index.

NOTE: This operation may run in O(maxDoc). Implementations that can't return this number in constant-time should cache it.

Specified by:
  `numDocs` in class `IndexReader`

### maxDoc

public int maxDoc()
Description copied from class: `IndexReader`
Returns one greater than the largest possible document number. This may be used to, e.g., determine how big to allocate an array which will have an element for every document number in an index.

Specified by:
  `maxDoc` in class `IndexReader`

### storedFields

public StoredFields storedFields() throws IOException
Description copied from class: `IndexReader`
Returns a `StoredFields` reader for the stored fields of this index.

This call never returns `null`, even if no stored fields were indexed. The returned instance should only be used by a single thread.

Example:

     TopDocs hits = searcher.search(query, 10);
     StoredFields storedFields = reader.storedFields();
     for (ScoreDoc hit : hits.scoreDocs) {
       Document doc = storedFields.document(hit.doc);
     }

Specified by:
  `storedFields` in class `IndexReader`
Throws:
  `IOException` - If there is a low-level IO error

### getCoreCacheHelper

public IndexReader.CacheHelper getCoreCacheHelper()
Description copied from class: `LeafReader`
Optional method: Return a `IndexReader.CacheHelper` that can be used to cache based on the content of this leaf regardless of deletions. Two readers that have the same data but different sets of deleted documents or doc values updates may be considered equal. Consider using `IndexReader.getReaderCacheHelper()` if you need deletions or dv updates to be taken into account.

A return value of `null` indicates that this reader is not suited for caching, which is typically the case for short-lived wrappers that alter the content of the wrapped leaf reader.

Specified by:
  `getCoreCacheHelper` in class `LeafReader`

### getReaderCacheHelper

public IndexReader.CacheHelper getReaderCacheHelper()
Description copied from class: `IndexReader`
Optional method: Return a `IndexReader.CacheHelper` that can be used to cache based on the content of this reader. Two readers that have different data or different sets of deleted documents will be considered different.

A return value of `null` indicates that this reader is not suited for caching, which is typically the case for short-lived wrappers that alter the content of the wrapped reader.

Specified by:
  `getReaderCacheHelper` in class `IndexReader`

### termVectors

public TermVectors termVectors() throws IOException
Description copied from class: `IndexReader`
Returns a `TermVectors` reader for the term vectors of this index.

This call never returns `null`, even if no term vectors were indexed. The returned instance should only be used by a single thread.

Example:

     TopDocs hits = searcher.search(query, 10);
     TermVectors termVectors = reader.termVectors();
     for (ScoreDoc hit : hits.scoreDocs) {
       Fields vector = termVectors.get(hit.doc);
     }

Specified by:
  `termVectors` in class `IndexReader`
Throws:
  `IOException` - If there is a low-level IO error

### doClose

protected void doClose() throws IOException
Description copied from class: `IndexReader`
Implements close.

Specified by:
  `doClose` in class `IndexReader`
Throws:
  `IOException`

### getNumericDocValues

public NumericDocValues getNumericDocValues(String field) throws IOException
Description copied from class: `LeafReader`
Returns `NumericDocValues` for this field, or null if no numeric doc values were indexed for this field. The returned instance should only be used by a single thread.

Specified by:
  `getNumericDocValues` in class `LeafReader`
Throws:
  `IOException`

### getBinaryDocValues

public BinaryDocValues getBinaryDocValues(String field) throws IOException
Description copied from class: `LeafReader`
Returns `BinaryDocValues` for this field, or null if no binary doc values were indexed for this field. The returned instance should only be used by a single thread.

Specified by:
  `getBinaryDocValues` in class `LeafReader`
Throws:
  `IOException`

### getSortedDocValues

public SortedDocValues getSortedDocValues(String field) throws IOException
Description copied from class: `LeafReader`
Returns `SortedDocValues` for this field, or null if no `SortedDocValues` were indexed for this field. The returned instance should only be used by a single thread.

Specified by:
  `getSortedDocValues` in class `LeafReader`
Throws:
  `IOException`

### getSortedNumericDocValues

public SortedNumericDocValues getSortedNumericDocValues(String field) throws IOException
Description copied from class: `LeafReader`
Returns `SortedNumericDocValues` for this field, or null if no `SortedNumericDocValues` were indexed for this field. The returned instance should only be used by a single thread.

Specified by:
  `getSortedNumericDocValues` in class `LeafReader`
Throws:
  `IOException`

### getSortedSetDocValues

public SortedSetDocValues getSortedSetDocValues(String field) throws IOException
Description copied from class: `LeafReader`
Returns `SortedSetDocValues` for this field, or null if no `SortedSetDocValues` were indexed for this field. The returned instance should only be used by a single thread.

Specified by:
  `getSortedSetDocValues` in class `LeafReader`
Throws:
  `IOException`

### getDocValuesSkipper

public DocValuesSkipper getDocValuesSkipper(String field) throws IOException
Description copied from class: `LeafReader`
Returns a `DocValuesSkipper` allowing skipping ranges of doc IDs that are not of interest, or `null` if a skip index was not indexed. The returned instance should be confined to the thread that created it.

Specified by:
  `getDocValuesSkipper` in class `LeafReader`
Throws:
  `IOException`

### getNormValues

public NumericDocValues getNormValues(String field) throws IOException
Description copied from class: `LeafReader`
Returns `NumericDocValues` representing norms for this field, or null if no `NumericDocValues` were indexed. The returned instance should only be used by a single thread.

Specified by:
  `getNormValues` in class `LeafReader`
Throws:
  `IOException`

### getPointValues

public PointValues getPointValues(String fieldName) throws IOException
Description copied from class: `LeafReader`
Returns the `PointValues` used for numeric or spatial searches for the given field, or null if there are no point fields.

Specified by:
  `getPointValues` in class `LeafReader`
Throws:
  `IOException`

### getFloatVectorValues

public FloatVectorValues getFloatVectorValues(String fieldName) throws IOException
Description copied from class: `LeafReader`
Returns `FloatVectorValues` for this field, or null if no `FloatVectorValues` were indexed. The returned instance should only be used by a single thread.

Specified by:
  `getFloatVectorValues` in class `LeafReader`
Throws:
  `IOException`

### getByteVectorValues

public ByteVectorValues getByteVectorValues(String fieldName) throws IOException
Description copied from class: `LeafReader`
Returns `ByteVectorValues` for this field, or null if no `ByteVectorValues` were indexed. The returned instance should only be used by a single thread.

Specified by:
  `getByteVectorValues` in class `LeafReader`
Throws:
  `IOException`

### searchNearestVectors

public void searchNearestVectors(String fieldName, float[] target, KnnCollector knnCollector, Bits acceptDocs) throws IOException
Description copied from class: `LeafReader`
Return the k nearest neighbor documents as determined by comparison of their vector values for this field, to the given vector, by the field's similarity function. The score of each document is derived from the vector similarity in a way that ensures scores are positive and that a larger score corresponds to a higher ranking.

The search is allowed to be approximate, meaning the results are not guaranteed to be the true k closest neighbors. For large values of k (for example when k is close to the total number of documents), the search may also retrieve fewer than k documents.

The returned `TopDocs` will contain a `ScoreDoc` for each nearest neighbor, in order of their similarity to the query vector (decreasing scores). The `TotalHits` contains the number of documents visited during the search. If the search stopped early because it hit `visitedLimit`, it is indicated through the relation `TotalHits.Relation.GREATER_THAN_OR_EQUAL_TO`.

The behavior is undefined if the given field doesn't have KNN vectors enabled on its `FieldInfo`. The return value is never `null`.

Specified by:
  `searchNearestVectors` in class `LeafReader`
Parameters:
  `fieldName` - the vector field to search
  `target` - the vector-valued query
  `knnCollector` - collector with settings for gathering the vector results.
  `acceptDocs` - `Bits` that represents the allowed documents to match, or `null` if they are all allowed to match.
Throws:
  `IOException`

### searchNearestVectors

public void searchNearestVectors(String fieldName, byte[] target, KnnCollector knnCollector, Bits acceptDocs) throws IOException
Description copied from class: `LeafReader`
Return the k nearest neighbor documents as determined by comparison of their vector values for this field, to the given vector, by the field's similarity function. The score of each document is derived from the vector similarity in a way that ensures scores are positive and that a larger score corresponds to a higher ranking.

The search is allowed to be approximate, meaning the results are not guaranteed to be the true k closest neighbors. For large values of k (for example when k is close to the total number of documents), the search may also retrieve fewer than k documents.

The returned `TopDocs` will contain a `ScoreDoc` for each nearest neighbor, in order of their similarity to the query vector (decreasing scores). The `TotalHits` contains the number of documents visited during the search. If the search stopped early because it hit `visitedLimit`, it is indicated through the relation `TotalHits.Relation.GREATER_THAN_OR_EQUAL_TO`.

The behavior is undefined if the given field doesn't have KNN vectors enabled on its `FieldInfo`. The return value is never `null`.

Specified by:
  `searchNearestVectors` in class `LeafReader`
Parameters:
  `fieldName` - the vector field to search
  `target` - the vector-valued query
  `knnCollector` - collector with settings for gathering the vector results.
  `acceptDocs` - `Bits` that represents the allowed documents to match, or `null` if they are all allowed to match.
Throws:
  `IOException`

### checkIntegrity

public void checkIntegrity() throws IOException
Description copied from class: `LeafReader`
Checks consistency of this reader.

Note that this may be costly in terms of I/O, e.g. may involve computing a checksum value against large data files.

Specified by:
  `checkIntegrity` in class `LeafReader`
Throws:
  `IOException`

### getParallelReaders

public LeafReader[] getParallelReaders()
Returns the `LeafReader`s that were passed on init.

### getMetaData

public LeafMetaData getMetaData()
Description copied from class: `LeafReader`
Return metadata about this leaf.

Specified by:
  `getMetaData` in class `LeafReader`