Class Lucene90BlockTreeTermsReader
java.lang.Object
org.apache.lucene.index.Fields
org.apache.lucene.codecs.FieldsProducer
org.apache.lucene.codecs.lucene90.blocktree.Lucene90BlockTreeTermsReader
- All Implemented Interfaces:
Closeable
,AutoCloseable
,Iterable<String>
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 CheckIndex
with the -verbose
option 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
Modifier and TypeFieldDescriptionstatic final int
Current terms format.static final int
The version that specialize arc store for continuous label in FST.static final int
Version that encode output as MSB VLong for better outputs sharing in FST, see GITHUB#12620.static final int
Initial terms format.Fields inherited from class org.apache.lucene.index.Fields
EMPTY_ARRAY
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Constructor Summary
ConstructorDescriptionLucene90BlockTreeTermsReader
(PostingsReaderBase postingsReader, SegmentReadState state) Sole constructor. -
Method Summary
Methods inherited from class org.apache.lucene.codecs.FieldsProducer
getMergeInstance
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
Methods inherited from interface java.lang.Iterable
forEach, spliterator
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Field Details
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VERSION_START
public static final int VERSION_STARTInitial terms format.- See Also:
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VERSION_MSB_VLONG_OUTPUT
public static final int VERSION_MSB_VLONG_OUTPUTVersion that encode output as MSB VLong for better outputs sharing in FST, see GITHUB#12620.- See Also:
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VERSION_FST_CONTINUOUS_ARCS
public static final int VERSION_FST_CONTINUOUS_ARCSThe version that specialize arc store for continuous label in FST.- See Also:
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VERSION_CURRENT
public static final int VERSION_CURRENTCurrent terms format.- See Also:
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Constructor Details
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Lucene90BlockTreeTermsReader
public Lucene90BlockTreeTermsReader(PostingsReaderBase postingsReader, SegmentReadState state) throws IOException Sole constructor.- Throws:
IOException
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Method Details
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close
- Specified by:
close
in interfaceAutoCloseable
- Specified by:
close
in interfaceCloseable
- Specified by:
close
in classFieldsProducer
- Throws:
IOException
-
iterator
Description copied from class:Fields
Returns an iterator that will step through all fields names. This will not return null. -
terms
Description copied from class:Fields
Get theTerms
for this field. This will return null if the field does not exist.- Specified by:
terms
in classFields
- Throws:
IOException
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size
public int size()Description copied from class:Fields
Returns 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. -
checkIntegrity
Description copied from class:FieldsProducer
Checks 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:
checkIntegrity
in classFieldsProducer
- Throws:
IOException
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toString
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