Package org.apache.lucene.codecs.lucene60

Class Lucene60PointsFormat

java.lang.Object

org.apache.lucene.codecs.PointsFormat

org.apache.lucene.codecs.lucene60.Lucene60PointsFormat

public final 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)
• packedValue^count (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 String	DATA_EXTENSION	Filename extension for the leaf blocks
static 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)	Reads a segment.
PointsWriter	fieldsWriter(SegmentWriteState state)	Writes a new segment

Methods inherited from class java.lang.Object

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

Field Detail

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 Detail

Lucene60PointsFormat

public Lucene60PointsFormat()

Sole constructor

Method Detail

fieldsWriter

public PointsWriter fieldsWriter(SegmentWriteState state)
                          throws IOException

Description copied from class: PointsFormat

Writes a new segment

Specified by:

fieldsWriter in class PointsFormat

Throws:

IOException

fieldsReader

public PointsReader fieldsReader(SegmentReadState state)
                          throws IOException

Description copied from class: PointsFormat

Reads a segment. NOTE: by the time this call returns, it must hold open any files it will need to use; else, those files may be deleted. Additionally, required files may be deleted during the execution of this call before there is a chance to open them. Under these circumstances an IOException should be thrown by the implementation. IOExceptions are expected and will automatically cause a retry of the segment opening logic with the newly revised segments.

Specified by:

fieldsReader in class PointsFormat

Throws:

IOException