package org.apache.lucene.codecs.lucene45;
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
import java.io.IOException;
import org.apache.lucene.codecs.CodecUtil;
import org.apache.lucene.codecs.DocValuesConsumer;
import org.apache.lucene.codecs.DocValuesProducer;
import org.apache.lucene.codecs.DocValuesFormat;
import org.apache.lucene.index.SegmentReadState;
import org.apache.lucene.index.SegmentWriteState;
import org.apache.lucene.index.FieldInfo.DocValuesType;
import org.apache.lucene.store.DataOutput;
import org.apache.lucene.util.SmallFloat;
import org.apache.lucene.util.fst.FST;
import org.apache.lucene.util.packed.BlockPackedWriter;
import org.apache.lucene.util.packed.MonotonicBlockPackedWriter;
import org.apache.lucene.util.packed.PackedInts;
/**
* Lucene 4.5 DocValues format.
* <p>
* Encodes the four per-document value types (Numeric,Binary,Sorted,SortedSet) with these strategies:
* <p>
* {@link DocValuesType#NUMERIC NUMERIC}:
* <ul>
* <li>Delta-compressed: per-document integers written in blocks of 16k. For each block
* the minimum value in that block is encoded, and each entry is a delta from that
* minimum value. Each block of deltas is compressed with bitpacking. For more
* information, see {@link BlockPackedWriter}.
* <li>Table-compressed: when the number of unique values is very small (< 256), and
* when there are unused "gaps" in the range of values used (such as {@link SmallFloat}),
* a lookup table is written instead. Each per-document entry is instead the ordinal
* to this table, and those ordinals are compressed with bitpacking ({@link PackedInts}).
* <li>GCD-compressed: when all numbers share a common divisor, such as dates, the greatest
* common denominator (GCD) is computed, and quotients are stored using Delta-compressed Numerics.
* </ul>
* <p>
* {@link DocValuesType#BINARY BINARY}:
* <ul>
* <li>Fixed-width Binary: one large concatenated byte[] is written, along with the fixed length.
* Each document's value can be addressed directly with multiplication ({@code docID * length}).
* <li>Variable-width Binary: one large concatenated byte[] is written, along with end addresses
* for each document. The addresses are written in blocks of 16k, with the current absolute
* start for the block, and the average (expected) delta per entry. For each document the
* deviation from the delta (actual - expected) is written.
* <li>Prefix-compressed Binary: values are written in chunks of 16, with the first value written
* completely and other values sharing prefixes. chunk addresses are written in blocks of 16k,
* with the current absolute start for the block, and the average (expected) delta per entry.
* For each chunk the deviation from the delta (actual - expected) is written.
* </ul>
* <p>
* {@link DocValuesType#SORTED SORTED}:
* <ul>
* <li>Sorted: a mapping of ordinals to deduplicated terms is written as Prefix-Compressed Binary,
* along with the per-document ordinals written using one of the numeric strategies above.
* </ul>
* <p>
* {@link DocValuesType#SORTED_SET SORTED_SET}:
* <ul>
* <li>SortedSet: a mapping of ordinals to deduplicated terms is written as Prefix-Compressed Binary,
* an ordinal list and per-document index into this list are written using the numeric strategies
* above.
* </ul>
* <p>
* Files:
* <ol>
* <li><tt>.dvd</tt>: DocValues data</li>
* <li><tt>.dvm</tt>: DocValues metadata</li>
* </ol>
* <ol>
* <li><a name="dvm" id="dvm"></a>
* <p>The DocValues metadata or .dvm file.</p>
* <p>For DocValues field, this stores metadata, such as the offset into the
* DocValues data (.dvd)</p>
* <p>DocValues metadata (.dvm) --> Header,<Entry><sup>NumFields</sup></p>
* <ul>
* <li>Entry --> NumericEntry | BinaryEntry | SortedEntry | SortedSetEntry</li>
* <li>NumericEntry --> GCDNumericEntry | TableNumericEntry | DeltaNumericEntry</li>
* <li>GCDNumericEntry --> NumericHeader,MinValue,GCD</li>
* <li>TableNumericEntry --> NumericHeader,TableSize,{@link DataOutput#writeLong Int64}<sup>TableSize</sup></li>
* <li>DeltaNumericEntry --> NumericHeader</li>
* <li>NumericHeader --> FieldNumber,EntryType,NumericType,MissingOffset,PackedVersion,DataOffset,Count,BlockSize</li>
* <li>BinaryEntry --> FixedBinaryEntry | VariableBinaryEntry | PrefixBinaryEntry</li>
* <li>FixedBinaryEntry --> BinaryHeader</li>
* <li>VariableBinaryEntry --> BinaryHeader,AddressOffset,PackedVersion,BlockSize</li>
* <li>PrefixBinaryEntry --> BinaryHeader,AddressInterval,AddressOffset,PackedVersion,BlockSize</li>
* <li>BinaryHeader --> FieldNumber,EntryType,BinaryType,MissingOffset,MinLength,MaxLength,DataOffset</li>
* <li>SortedEntry --> FieldNumber,EntryType,BinaryEntry,NumericEntry</li>
* <li>SortedSetEntry --> EntryType,BinaryEntry,NumericEntry,NumericEntry</li>
* <li>FieldNumber,PackedVersion,MinLength,MaxLength,BlockSize,ValueCount --> {@link DataOutput#writeVInt VInt}</li>
* <li>EntryType,CompressionType --> {@link DataOutput#writeByte Byte}</li>
* <li>Header --> {@link CodecUtil#writeHeader CodecHeader}</li>
* <li>MinValue,GCD,MissingOffset,AddressOffset,DataOffset --> {@link DataOutput#writeLong Int64}</li>
* <li>TableSize --> {@link DataOutput#writeVInt vInt}</li>
* </ul>
* <p>Sorted fields have two entries: a BinaryEntry with the value metadata,
* and an ordinary NumericEntry for the document-to-ord metadata.</p>
* <p>SortedSet fields have three entries: a BinaryEntry with the value metadata,
* and two NumericEntries for the document-to-ord-index and ordinal list metadata.</p>
* <p>FieldNumber of -1 indicates the end of metadata.</p>
* <p>EntryType is a 0 (NumericEntry) or 1 (BinaryEntry)</p>
* <p>DataOffset is the pointer to the start of the data in the DocValues data (.dvd)</p>
* <p>NumericType indicates how Numeric values will be compressed:
* <ul>
* <li>0 --> delta-compressed. For each block of 16k integers, every integer is delta-encoded
* from the minimum value within the block.
* <li>1 -->, gcd-compressed. When all integers share a common divisor, only quotients are stored
* using blocks of delta-encoded ints.
* <li>2 --> table-compressed. When the number of unique numeric values is small and it would save space,
* a lookup table of unique values is written, followed by the ordinal for each document.
* </ul>
* <p>BinaryType indicates how Binary values will be stored:
* <ul>
* <li>0 --> fixed-width. All values have the same length, addressing by multiplication.
* <li>1 -->, variable-width. An address for each value is stored.
* <li>2 --> prefix-compressed. An address to the start of every interval'th value is stored.
* </ul>
* <p>MinLength and MaxLength represent the min and max byte[] value lengths for Binary values.
* If they are equal, then all values are of a fixed size, and can be addressed as DataOffset + (docID * length).
* Otherwise, the binary values are of variable size, and packed integer metadata (PackedVersion,BlockSize)
* is written for the addresses.
* <p>MissingOffset points to a byte[] containing a bitset of all documents that had a value for the field.
* If its -1, then there are no missing values.
* <li><a name="dvd" id="dvd"></a>
* <p>The DocValues data or .dvd file.</p>
* <p>For DocValues field, this stores the actual per-document data (the heavy-lifting)</p>
* <p>DocValues data (.dvd) --> Header,<NumericData | BinaryData | SortedData><sup>NumFields</sup></p>
* <ul>
* <li>NumericData --> DeltaCompressedNumerics | TableCompressedNumerics | GCDCompressedNumerics</li>
* <li>BinaryData --> {@link DataOutput#writeByte Byte}<sup>DataLength</sup>,Addresses</li>
* <li>SortedData --> {@link FST FST<Int64>}</li>
* <li>DeltaCompressedNumerics --> {@link BlockPackedWriter BlockPackedInts(blockSize=16k)}</li>
* <li>TableCompressedNumerics --> {@link PackedInts PackedInts}</li>
* <li>GCDCompressedNumerics --> {@link BlockPackedWriter BlockPackedInts(blockSize=16k)}</li>
* <li>Addresses --> {@link MonotonicBlockPackedWriter MonotonicBlockPackedInts(blockSize=16k)}</li>
* </ul>
* <p>SortedSet entries store the list of ordinals in their BinaryData as a
* sequences of increasing {@link DataOutput#writeVLong vLong}s, delta-encoded.</p>
* </ol>
* @lucene.experimental
*/
public final class Lucene45DocValuesFormat extends DocValuesFormat {
/** Sole Constructor */
public Lucene45DocValuesFormat() {
super("Lucene45");
}
@Override
public DocValuesConsumer fieldsConsumer(SegmentWriteState state) throws IOException {
return new Lucene45DocValuesConsumer(state, DATA_CODEC, DATA_EXTENSION, META_CODEC, META_EXTENSION);
}
@Override
public DocValuesProducer fieldsProducer(SegmentReadState state) throws IOException {
return new Lucene45DocValuesProducer(state, DATA_CODEC, DATA_EXTENSION, META_CODEC, META_EXTENSION);
}
static final String DATA_CODEC = "Lucene45DocValuesData";
static final String DATA_EXTENSION = "dvd";
static final String META_CODEC = "Lucene45ValuesMetadata";
static final String META_EXTENSION = "dvm";
static final int VERSION_START = 0;
static final int VERSION_SORTED_SET_SINGLE_VALUE_OPTIMIZED = 1;
static final int VERSION_CURRENT = VERSION_SORTED_SET_SINGLE_VALUE_OPTIMIZED;
static final byte NUMERIC = 0;
static final byte BINARY = 1;
static final byte SORTED = 2;
static final byte SORTED_SET = 3;
}