Package org.apache.lucene.backward_codecs.lucene60

# Class Lucene60PointsFormat

java.lang.Object
org.apache.lucene.codecs.PointsFormat
org.apache.lucene.backward_codecs.lucene60.Lucene60PointsFormat

public class Lucene60PointsFormat extends PointsFormat
Lucene 6.0 point format, which encodes dimensional values in a block KD-tree structure for fast 1D range and N dimensional shape intersection filtering. See this paper for details.

This data structure is written as a series of blocks on disk, with an in-memory perfectly balanced binary tree of split values referencing those blocks at the leaves.

The `.dim` file has both blocks and the index split values, for each field. The file starts with `CodecUtil.writeIndexHeader(org.apache.lucene.store.DataOutput, java.lang.String, int, byte[], java.lang.String)`.

The blocks are written like this:

- count (vInt)
- delta-docID (vInt) count (delta coded docIDs, in sorted order)
- packedValuecount (the `byte[]` value of each dimension packed into a single `byte[]`)

After all blocks for a field are written, then the index is written:

- numDims (vInt)
- maxPointsInLeafNode (vInt)
- bytesPerDim (vInt)
- count (vInt)
- packed index (byte[])

The packed index uses hierarchical delta and prefix coding to compactly encode the file pointer for all leaf blocks, once the tree is traversed, as well as the split dimension and split value for each inner node of the tree.

After all fields blocks + index data are written, `CodecUtil.writeFooter(org.apache.lucene.store.IndexOutput)` writes the checksum.

The `.dii` file records the file pointer in the `.dim` file where each field's index data was written. It starts with `CodecUtil.writeIndexHeader(org.apache.lucene.store.DataOutput, java.lang.String, int, byte[], java.lang.String)`, then has:

- fieldCount (vInt)
- (fieldNumber (vInt), fieldFilePointer (vLong))fieldCount

After all fields blocks + index data are written, `CodecUtil.writeFooter(org.apache.lucene.store.IndexOutput)` writes the checksum.

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

## Field Summary

Fields
Modifier and Type
Field
Description
`static final String`
`DATA_EXTENSION`
Filename extension for the leaf blocks
`static final String`
`INDEX_EXTENSION`
Filename extension for the index per field

### Fields inherited from class org.apache.lucene.codecs.PointsFormat

`EMPTY`

## Constructor Summary

Constructors
Constructor
Description
`Lucene60PointsFormat()`
Sole constructor

## Method Summary

Modifier and Type
Method
Description
`PointsReader`
`fieldsReader(SegmentReadState state)`
`PointsWriter`
`fieldsWriter(SegmentWriteState state)`

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

`clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

## Field Details

### DATA_EXTENSION

public static final String DATA_EXTENSION
Filename extension for the leaf blocks

See Also:
  - Constant Field Values

### INDEX_EXTENSION

public static final String INDEX_EXTENSION
Filename extension for the index per field

See Also:
  - Constant Field Values

## Constructor Details

### Lucene60PointsFormat

public Lucene60PointsFormat()
Sole constructor

## Method Details

### fieldsWriter

public PointsWriter fieldsWriter(SegmentWriteState state) throws IOException

Specified by:
  `fieldsWriter` in class `PointsFormat`
Throws:
  `IOException`

### fieldsReader

public PointsReader fieldsReader(SegmentReadState state) throws IOException

Specified by:
  `fieldsReader` in class `PointsFormat`
Throws:
  `IOException`