Package org.apache.lucene.util.packed

Packed integer arrays and streams.

See: Description

Interface Summary

Interface	Description
PackedInts.Decoder	A decoder for packed integers.
PackedInts.Encoder	An encoder for packed integers.
PackedInts.ReaderIterator	Run-once iterator interface, to decode previously saved PackedInts.

Class Summary

Class	Description
AbstractBlockPackedWriter
AbstractPagedMutable<T extends AbstractPagedMutable<T>>	Base implementation for PagedMutable and PagedGrowableWriter.
BlockPackedReader	Provides random access to a stream written with BlockPackedWriter.
BlockPackedReaderIterator	Reader for sequences of longs written with BlockPackedWriter.
BlockPackedWriter	A writer for large sequences of longs.
BulkOperation	Efficient sequential read/write of packed integers.
BulkOperationPacked	Non-specialized BulkOperation for PackedInts.Format.PACKED.
BulkOperationPacked1	Efficient sequential read/write of packed integers.
BulkOperationPacked10	Efficient sequential read/write of packed integers.
BulkOperationPacked11	Efficient sequential read/write of packed integers.
BulkOperationPacked12	Efficient sequential read/write of packed integers.
BulkOperationPacked13	Efficient sequential read/write of packed integers.
BulkOperationPacked14	Efficient sequential read/write of packed integers.
BulkOperationPacked15	Efficient sequential read/write of packed integers.
BulkOperationPacked16	Efficient sequential read/write of packed integers.
BulkOperationPacked17	Efficient sequential read/write of packed integers.
BulkOperationPacked18	Efficient sequential read/write of packed integers.
BulkOperationPacked19	Efficient sequential read/write of packed integers.
BulkOperationPacked2	Efficient sequential read/write of packed integers.
BulkOperationPacked20	Efficient sequential read/write of packed integers.
BulkOperationPacked21	Efficient sequential read/write of packed integers.
BulkOperationPacked22	Efficient sequential read/write of packed integers.
BulkOperationPacked23	Efficient sequential read/write of packed integers.
BulkOperationPacked24	Efficient sequential read/write of packed integers.
BulkOperationPacked3	Efficient sequential read/write of packed integers.
BulkOperationPacked4	Efficient sequential read/write of packed integers.
BulkOperationPacked5	Efficient sequential read/write of packed integers.
BulkOperationPacked6	Efficient sequential read/write of packed integers.
BulkOperationPacked7	Efficient sequential read/write of packed integers.
BulkOperationPacked8	Efficient sequential read/write of packed integers.
BulkOperationPacked9	Efficient sequential read/write of packed integers.
BulkOperationPackedSingleBlock	Non-specialized BulkOperation for PackedInts.Format.PACKED_SINGLE_BLOCK.
DeltaPackedLongValues
DeltaPackedLongValues.Builder
Direct16	Direct wrapping of 16-bits values to a backing array.
Direct32	Direct wrapping of 32-bits values to a backing array.
Direct64	Direct wrapping of 64-bits values to a backing array.
Direct8	Direct wrapping of 8-bits values to a backing array.
DirectMonotonicReader	Retrieves an instance previously written by DirectMonotonicWriter.
DirectMonotonicReader.Meta	In-memory metadata that needs to be kept around for DirectMonotonicReader to read data from disk.
DirectMonotonicWriter	Write monotonically-increasing sequences of integers.
DirectPacked64SingleBlockReader
DirectPackedReader
DirectReader	Retrieves an instance previously written by DirectWriter
DirectReader.DirectPackedReader1
DirectReader.DirectPackedReader12
DirectReader.DirectPackedReader16
DirectReader.DirectPackedReader2
DirectReader.DirectPackedReader20
DirectReader.DirectPackedReader24
DirectReader.DirectPackedReader28
DirectReader.DirectPackedReader32
DirectReader.DirectPackedReader4
DirectReader.DirectPackedReader40
DirectReader.DirectPackedReader48
DirectReader.DirectPackedReader56
DirectReader.DirectPackedReader64
DirectReader.DirectPackedReader8
DirectWriter	Class for writing packed integers to be directly read from Directory.
GrowableWriter	Implements PackedInts.Mutable, but grows the bit count of the underlying packed ints on-demand.
MonotonicBlockPackedReader	Provides random access to a stream written with MonotonicBlockPackedWriter.
MonotonicBlockPackedWriter	A writer for large monotonically increasing sequences of positive longs.
MonotonicLongValues
MonotonicLongValues.Builder
Packed16ThreeBlocks	Packs integers into 3 shorts (48 bits per value).
Packed64	Space optimized random access capable array of values with a fixed number of bits/value.
Packed64SingleBlock	This class is similar to Packed64 except that it trades space for speed by ensuring that a single block needs to be read/written in order to read/write a value.
Packed64SingleBlock.Packed64SingleBlock1
Packed64SingleBlock.Packed64SingleBlock10
Packed64SingleBlock.Packed64SingleBlock12
Packed64SingleBlock.Packed64SingleBlock16
Packed64SingleBlock.Packed64SingleBlock2
Packed64SingleBlock.Packed64SingleBlock21
Packed64SingleBlock.Packed64SingleBlock3
Packed64SingleBlock.Packed64SingleBlock32
Packed64SingleBlock.Packed64SingleBlock4
Packed64SingleBlock.Packed64SingleBlock5
Packed64SingleBlock.Packed64SingleBlock6
Packed64SingleBlock.Packed64SingleBlock7
Packed64SingleBlock.Packed64SingleBlock8
Packed64SingleBlock.Packed64SingleBlock9
Packed8ThreeBlocks	Packs integers into 3 bytes (24 bits per value).
PackedDataInput	A DataInput wrapper to read unaligned, variable-length packed integers.
PackedDataOutput	A DataOutput wrapper to write unaligned, variable-length packed integers.
PackedInts	Simplistic compression for array of unsigned long values.
PackedInts.FormatAndBits	Simple class that holds a format and a number of bits per value.
PackedInts.Mutable	A packed integer array that can be modified.
PackedInts.MutableImpl
PackedInts.NullReader	A PackedInts.Reader which has all its values equal to 0 (bitsPerValue = 0).
PackedInts.Reader	A read-only random access array of positive integers.
PackedInts.ReaderImpl	A simple base for Readers that keeps track of valueCount and bitsPerValue.
PackedInts.ReaderIteratorImpl
PackedInts.Writer	A write-once Writer.
PackedLongValues	Utility class to compress integers into a LongValues instance.
PackedLongValues.Builder	A Builder for a PackedLongValues instance.
PackedReaderIterator
PackedWriter
PagedGrowableWriter	A PagedGrowableWriter.
PagedMutable	A PagedMutable.

Enum Summary

Enum	Description
PackedInts.Format	A format to write packed ints.

Package org.apache.lucene.util.packed Description

Packed integer arrays and streams.

The packed package provides

• sequential and random access capable arrays of positive longs,
• routines for efficient serialization and deserialization of streams of packed integers.

The implementations provide different trade-offs between memory usage and access speed. The standard usage scenario is replacing large int or long arrays in order to reduce the memory footprint.

The main access point is the PackedInts factory.

In-memory structures

• PackedInts.Mutable
  • Only supports positive longs.
  • Requires the number of bits per value to be known in advance.
  • Random-access for both writing and reading.
• GrowableWriter
  • Same as PackedInts.Mutable but grows the number of bits per values when needed.
  • Useful to build a PackedInts.Mutable from a read-once stream of longs.
• PagedGrowableWriter
  • Slices data into fixed-size blocks stored in GrowableWriters.
  • Supports more than 2B values.
  • You should use PackedLongValues instead if you don't need random write access.
• PackedLongValues.deltaPackedBuilder(int, float)
  • Can store any sequence of longs.
  • Compression is good when values are close to each other.
  • Supports random reads, but only sequential writes.
  • Can address up to 2^42 values.
• PackedLongValues.packedBuilder(int, float)
  • Same as deltaPackedBuilder but assumes values are 0-based.
• PackedLongValues.monotonicBuilder(int, float)
  • Same as deltaPackedBuilder except that compression is good when the stream is a succession of affine functions.

Disk-based structures

• PackedInts.Writer, PackedInts.Reader, PackedInts.ReaderIterator
  • Only supports positive longs.
  • Requires the number of bits per value to be known in advance.
  • Supports both fast sequential access with low memory footprint with ReaderIterator and random-access by either loading values in memory or leaving them on disk with Reader.
• BlockPackedWriter, BlockPackedReader, BlockPackedReaderIterator
  • Splits the stream into fixed-size blocks.
  • Compression is good when values are close to each other.
  • Can address up to 2B * blockSize values.
• MonotonicBlockPackedWriter, MonotonicBlockPackedReader
  • Same as the non-monotonic variants except that compression is good when the stream is a succession of affine functions.
  • The reason why there is no sequential access is that if you need sequential access, you should rather delta-encode and use BlockPackedWriter.
• PackedDataOutput, PackedDataInput
  • Writes sequences of longs where each long can use any number of bits.