Class Lucene90BlockTreeTermsReader
- java.lang.Object
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- org.apache.lucene.index.Fields
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- org.apache.lucene.codecs.FieldsProducer
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- org.apache.lucene.codecs.lucene90.blocktree.Lucene90BlockTreeTermsReader
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- All Implemented Interfaces:
Closeable,AutoCloseable,Iterable<String>
public final class Lucene90BlockTreeTermsReader extends FieldsProducer
A block-based terms index and dictionary that assigns terms to variable length blocks according to how they share prefixes. The terms index is a prefix trie whose leaves are term blocks. The advantage of this approach is that seekExact is often able to determine a term cannot exist without doing any IO, and intersection with Automata is very fast. Note that this terms dictionary has its own fixed terms index (ie, it does not support a pluggable terms index implementation).NOTE: this terms dictionary supports min/maxItemsPerBlock during indexing to control how much memory the terms index uses.
The data structure used by this implementation is very similar to a burst trie (http://citeseer.ist.psu.edu/viewdoc/summary?doi=10.1.1.18.3499), but with added logic to break up too-large blocks of all terms sharing a given prefix into smaller ones.
Use
CheckIndexwith the-verboseoption to see summary statistics on the blocks in the dictionary.- WARNING: This API is experimental and might change in incompatible ways in the next release.
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Field Summary
Fields Modifier and Type Field Description static intVERSION_CURRENTCurrent terms format.static intVERSION_FST_CONTINUOUS_ARCSThe version that specialize arc store for continuous label in FST.static intVERSION_MSB_VLONG_OUTPUTVersion that encode output as MSB VLong for better outputs sharing in FST, see GITHUB#12620.static intVERSION_STARTInitial terms format.-
Fields inherited from class org.apache.lucene.index.Fields
EMPTY_ARRAY
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Constructor Summary
Constructors Constructor Description Lucene90BlockTreeTermsReader(PostingsReaderBase postingsReader, SegmentReadState state)Sole constructor.
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description voidcheckIntegrity()Checks consistency of this reader.voidclose()Iterator<String>iterator()Returns an iterator that will step through all fields names.intsize()Returns the number of fields or -1 if the number of distinct field names is unknown.Termsterms(String field)Get theTermsfor this field.StringtoString()-
Methods inherited from class org.apache.lucene.codecs.FieldsProducer
getMergeInstance
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Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
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Methods inherited from interface java.lang.Iterable
forEach, spliterator
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Field Detail
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VERSION_START
public static final int VERSION_START
Initial terms format.- See Also:
- Constant Field Values
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VERSION_MSB_VLONG_OUTPUT
public static final int VERSION_MSB_VLONG_OUTPUT
Version that encode output as MSB VLong for better outputs sharing in FST, see GITHUB#12620.- See Also:
- Constant Field Values
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VERSION_FST_CONTINUOUS_ARCS
public static final int VERSION_FST_CONTINUOUS_ARCS
The version that specialize arc store for continuous label in FST.- See Also:
- Constant Field Values
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VERSION_CURRENT
public static final int VERSION_CURRENT
Current terms format.- See Also:
- Constant Field Values
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Constructor Detail
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Lucene90BlockTreeTermsReader
public Lucene90BlockTreeTermsReader(PostingsReaderBase postingsReader, SegmentReadState state) throws IOException
Sole constructor.- Throws:
IOException
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Method Detail
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close
public void close() throws IOException- Specified by:
closein interfaceAutoCloseable- Specified by:
closein interfaceCloseable- Specified by:
closein classFieldsProducer- Throws:
IOException
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iterator
public Iterator<String> iterator()
Description copied from class:FieldsReturns an iterator that will step through all fields names. This will not return null.
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terms
public Terms terms(String field) throws IOException
Description copied from class:FieldsGet theTermsfor this field. This will return null if the field does not exist.- Specified by:
termsin classFields- Throws:
IOException
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size
public int size()
Description copied from class:FieldsReturns the number of fields or -1 if the number of distinct field names is unknown. If >= 0,Fields.iterator()will return as many field names.
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checkIntegrity
public void checkIntegrity() throws IOExceptionDescription copied from class:FieldsProducerChecks 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:
checkIntegrityin classFieldsProducer- Throws:
IOException
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