java.lang.Object
- org.apache.lucene.codecs.FieldsConsumer
- - org.apache.lucene.codecs.BlockTreeTermsWriter

All Implemented Interfaces:

Closeable, AutoCloseable
```
public class BlockTreeTermsWriter
extends FieldsConsumer
```
Block-based terms index and dictionary writer.
Writes terms dict and index, block-encoding (column stride) each term's metadata for each set of terms between two index terms.
Files:
- .tim: Term Dictionary
- .tip: Term Index
Term Dictionary

The .tim file contains the list of terms in each field along with per-term statistics (such as docfreq) and per-term metadata (typically pointers to the postings list for that term in the inverted index).

The .tim is arranged in blocks: with blocks containing a variable number of entries (by default 25-48), where each entry is either a term or a reference to a sub-block.

NOTE: The term dictionary can plug into different postings implementations: the postings writer/reader are actually responsible for encoding and decoding the Postings Metadata and Term Metadata sections.
- TermsDict (.tim) --> Header, PostingsHeader, NodeBlock^NumBlocks, FieldSummary, DirOffset
- NodeBlock --> (OuterNode | InnerNode)
- OuterNode --> EntryCount, SuffixLength, Byte^SuffixLength, StatsLength, < TermStats >^EntryCount, MetaLength, <TermMetadata>^EntryCount
- InnerNode --> EntryCount, SuffixLength[,Sub?], Byte^SuffixLength, StatsLength, < TermStats ? >^EntryCount, MetaLength, <TermMetadata ? >^EntryCount
- TermStats --> DocFreq, TotalTermFreq
- FieldSummary --> NumFields, <FieldNumber, NumTerms, RootCodeLength, Byte^{RootCodeLength}, SumTotalTermFreq?, SumDocFreq, DocCount>^NumFields
- Header --> CodecHeader
- DirOffset --> Uint64
- EntryCount,SuffixLength,StatsLength,DocFreq,MetaLength,NumFields, FieldNumber,RootCodeLength,DocCount --> VInt
- TotalTermFreq,NumTerms,SumTotalTermFreq,SumDocFreq --> VLong
Notes:
- Header is a CodecHeader storing the version information for the BlockTree implementation.
- DirOffset is a pointer to the FieldSummary section.
- DocFreq is the count of documents which contain the term.
- TotalTermFreq is the total number of occurrences of the term. This is encoded as the difference between the total number of occurrences and the DocFreq.
- FieldNumber is the fields number from FieldInfos. (.fnm)
- NumTerms is the number of unique terms for the field.
- RootCode points to the root block for the field.
- SumDocFreq is the total number of postings, the number of term-document pairs across the entire field.
- DocCount is the number of documents that have at least one posting for this field.
- PostingsHeader and TermMetadata are plugged into by the specific postings implementation: these contain arbitrary per-file data (such as parameters or versioning information) and per-term data (such as pointers to inverted files).
- For inner nodes of the tree, every entry will steal one bit to mark whether it points to child nodes(sub-block). If so, the corresponding TermStats and TermMetaData are omitted
Term Index

The .tip file contains an index into the term dictionary, so that it can be accessed randomly. The index is also used to determine when a given term cannot exist on disk (in the .tim file), saving a disk seek.
- TermsIndex (.tip) --> Header, FSTIndex^NumFields <IndexStartFP>^NumFields, DirOffset
- Header --> CodecHeader
- DirOffset --> Uint64
- IndexStartFP --> VLong
- FSTIndex --> FST<byte[]>
Notes:
- The .tip file contains a separate FST for each field. The FST maps a term prefix to the on-disk block that holds all terms starting with that prefix. Each field's IndexStartFP points to its FST.
- DirOffset is a pointer to the start of the IndexStartFPs for all fields
- It's possible that an on-disk block would contain too many terms (more than the allowed maximum (default: 48)). When this happens, the block is sub-divided into new blocks (called "floor blocks"), and then the output in the FST for the block's prefix encodes the leading byte of each sub-block, and its file pointer.
See Also:

BlockTreeTermsReader

Field Summary

Fields
Modifier and Type	Field	Description
`static int`	`DEFAULT_MAX_BLOCK_SIZE`	Suggested default value for the `maxItemsInBlock` parameter to `BlockTreeTermsWriter(SegmentWriteState,PostingsWriterBase,int,int)`.
`static int`	`DEFAULT_MIN_BLOCK_SIZE`	Suggested default value for the `minItemsInBlock` parameter to `BlockTreeTermsWriter(SegmentWriteState,PostingsWriterBase,int,int)`.
`static int`	`TERMS_INDEX_VERSION_APPEND_ONLY`	Append-only
`static int`	`TERMS_INDEX_VERSION_CURRENT`	Current index format.
`static int`	`TERMS_INDEX_VERSION_META_ARRAY`	Meta data as array
`static int`	`TERMS_INDEX_VERSION_START`	Initial index format.
`static int`	`TERMS_VERSION_APPEND_ONLY`	Append-only
`static int`	`TERMS_VERSION_CURRENT`	Current terms format.
`static int`	`TERMS_VERSION_META_ARRAY`	Meta data as array
`static int`	`TERMS_VERSION_START`	Initial terms format.

Constructor Summary

Constructors
Constructor	Description
`BlockTreeTermsWriter(SegmentWriteState state, PostingsWriterBase postingsWriter, int minItemsInBlock, int maxItemsInBlock)`	Create a new writer.

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`TermsConsumer`	`addField(FieldInfo field)`	Add a new field
`void`	`close()`	Called when we are done adding everything.
`protected void`	`writeHeader(IndexOutput out)`	Writes the terms file header.
`protected void`	`writeIndexHeader(IndexOutput out)`	Writes the index file header.
`protected void`	`writeIndexTrailer(IndexOutput indexOut, long dirStart)`	Writes the index file trailer.
`protected void`	`writeTrailer(IndexOutput out, long dirStart)`	Writes the terms file trailer.

Methods inherited from class org.apache.lucene.codecs.FieldsConsumer
merge

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - DEFAULT_MIN_BLOCK_SIZE
```
public static final int DEFAULT_MIN_BLOCK_SIZE
```
    Suggested default value for the minItemsInBlock parameter to BlockTreeTermsWriter(SegmentWriteState,PostingsWriterBase,int,int).
    
    See Also:
    
    Constant Field Values
  - DEFAULT_MAX_BLOCK_SIZE
```
public static final int DEFAULT_MAX_BLOCK_SIZE
```
    Suggested default value for the maxItemsInBlock parameter to BlockTreeTermsWriter(SegmentWriteState,PostingsWriterBase,int,int).
    
    See Also:
    
    Constant Field Values
  - TERMS_VERSION_START
```
public static final int TERMS_VERSION_START
```
    Initial terms format.
    
    See Also:
    
    Constant Field Values
  - TERMS_VERSION_APPEND_ONLY
```
public static final int TERMS_VERSION_APPEND_ONLY
```
    Append-only
    
    See Also:
    
    Constant Field Values
  - TERMS_VERSION_META_ARRAY
```
public static final int TERMS_VERSION_META_ARRAY
```
    Meta data as array
    
    See Also:
    
    Constant Field Values
  - TERMS_VERSION_CURRENT
```
public static final int TERMS_VERSION_CURRENT
```
    Current terms format.
    
    See Also:
    
    Constant Field Values
  - TERMS_INDEX_VERSION_START
```
public static final int TERMS_INDEX_VERSION_START
```
    Initial index format.
    
    See Also:
    
    Constant Field Values
  - TERMS_INDEX_VERSION_APPEND_ONLY
```
public static final int TERMS_INDEX_VERSION_APPEND_ONLY
```
    Append-only
    
    See Also:
    
    Constant Field Values
  - TERMS_INDEX_VERSION_META_ARRAY
```
public static final int TERMS_INDEX_VERSION_META_ARRAY
```
    Meta data as array
    
    See Also:
    
    Constant Field Values
  - TERMS_INDEX_VERSION_CURRENT
```
public static final int TERMS_INDEX_VERSION_CURRENT
```
    Current index format.
    
    See Also:
    
    Constant Field Values
- Constructor Detail
  - BlockTreeTermsWriter
```
public BlockTreeTermsWriter(SegmentWriteState state,
                            PostingsWriterBase postingsWriter,
                            int minItemsInBlock,
                            int maxItemsInBlock)
                     throws IOException
```
    Create a new writer. The number of items (terms or sub-blocks) per block will aim to be between minItemsPerBlock and maxItemsPerBlock, though in some cases the blocks may be smaller than the min.
    
    Throws:
    
    IOException
- Method Detail
  - writeHeader
```
protected void writeHeader(IndexOutput out)
                    throws IOException
```
    Writes the terms file header.
    
    Throws:
    
    IOException
  - writeIndexHeader
```
protected void writeIndexHeader(IndexOutput out)
                         throws IOException
```
    Writes the index file header.
    
    Throws:
    
    IOException
  - writeTrailer
```
protected void writeTrailer(IndexOutput out,
                            long dirStart)
                     throws IOException
```
    Writes the terms file trailer.
    
    Throws:
    
    IOException
  - writeIndexTrailer
```
protected void writeIndexTrailer(IndexOutput indexOut,
                                 long dirStart)
                          throws IOException
```
    Writes the index file trailer.
    
    Throws:
    
    IOException
  - addField
```
public TermsConsumer addField(FieldInfo field)
                       throws IOException
```
    Description copied from class: FieldsConsumer
    
    Add a new field
    
    Specified by:
    
    addField in class FieldsConsumer
    
    Throws:
    
    IOException
  - close
```
public void close()
           throws IOException
```
    Description copied from class: FieldsConsumer
    
    Called when we are done adding everything.
    
    Specified by:
    
    close in interface AutoCloseable
    
    Specified by:
    
    close in interface Closeable
    
    Specified by:
    
    close in class FieldsConsumer
    
    Throws:
    
    IOException

Class BlockTreeTermsWriter

Term Dictionary

Term Index

Field Summary

Constructor Summary

Method Summary

Methods inherited from class org.apache.lucene.codecs.FieldsConsumer

Methods inherited from class java.lang.Object

Field Detail

DEFAULT_MIN_BLOCK_SIZE

DEFAULT_MAX_BLOCK_SIZE

TERMS_VERSION_START

TERMS_VERSION_APPEND_ONLY

TERMS_VERSION_META_ARRAY

TERMS_VERSION_CURRENT

TERMS_INDEX_VERSION_START

TERMS_INDEX_VERSION_APPEND_ONLY

TERMS_INDEX_VERSION_META_ARRAY

TERMS_INDEX_VERSION_CURRENT

Constructor Detail

BlockTreeTermsWriter

Method Detail

writeHeader

writeIndexHeader

writeTrailer

writeIndexTrailer

addField

close