public class QueryAutoStopWordAnalyzer extends Analyzer
Analyzer
used primarily at query time to wrap another analyzer and provide a layer of protection
which prevents very common words from being passed into queries.
For very large indexes the cost of reading TermDocs for a very common word can be high. This analyzer was created after experience with a 38 million doc index which had a term in around 50% of docs and was causing TermQueries for this term to take 2 seconds.
Use the various "addStopWords" methods in this class to automate the identification and addition of stop words found in an already existing index.
Modifier and Type | Field and Description |
---|---|
static float |
defaultMaxDocFreqPercent |
overridesTokenStreamMethod
Constructor and Description |
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QueryAutoStopWordAnalyzer(Analyzer delegate)
Deprecated.
Use
QueryAutoStopWordAnalyzer(Version, Analyzer) instead |
QueryAutoStopWordAnalyzer(Version matchVersion,
Analyzer delegate)
Initializes this analyzer with the Analyzer object that actually produces the tokens
|
Modifier and Type | Method and Description |
---|---|
int |
addStopWords(IndexReader reader)
Automatically adds stop words for all fields with terms exceeding the defaultMaxDocFreqPercent
|
int |
addStopWords(IndexReader reader,
float maxPercentDocs)
Automatically adds stop words for all fields with terms exceeding the maxDocFreqPercent
|
int |
addStopWords(IndexReader reader,
int maxDocFreq)
Automatically adds stop words for all fields with terms exceeding the maxDocFreqPercent
|
int |
addStopWords(IndexReader reader,
java.lang.String fieldName,
float maxPercentDocs)
Automatically adds stop words for the given field with terms exceeding the maxPercentDocs
|
int |
addStopWords(IndexReader reader,
java.lang.String fieldName,
int maxDocFreq)
Automatically adds stop words for the given field with terms exceeding the maxPercentDocs
|
Term[] |
getStopWords()
Provides information on which stop words have been identified for all fields
|
java.lang.String[] |
getStopWords(java.lang.String fieldName)
Provides information on which stop words have been identified for a field
|
TokenStream |
reusableTokenStream(java.lang.String fieldName,
java.io.Reader reader)
Creates a TokenStream that is allowed to be re-used
from the previous time that the same thread called
this method.
|
TokenStream |
tokenStream(java.lang.String fieldName,
java.io.Reader reader)
Creates a TokenStream which tokenizes all the text in the provided
Reader.
|
close, getOffsetGap, getPositionIncrementGap, getPreviousTokenStream, setOverridesTokenStreamMethod, setPreviousTokenStream
public static final float defaultMaxDocFreqPercent
public QueryAutoStopWordAnalyzer(Analyzer delegate)
QueryAutoStopWordAnalyzer(Version, Analyzer)
insteaddelegate
- The choice of Analyzer
that is used to produce the token stream which needs filteringpublic int addStopWords(IndexReader reader) throws java.io.IOException
reader
- The IndexReader
which will be consulted to identify potential stop words that
exceed the required document frequencyjava.io.IOException
public int addStopWords(IndexReader reader, int maxDocFreq) throws java.io.IOException
reader
- The IndexReader
which will be consulted to identify potential stop words that
exceed the required document frequencymaxDocFreq
- The maximum number of index documents which can contain a term, after which
the term is considered to be a stop wordjava.io.IOException
public int addStopWords(IndexReader reader, float maxPercentDocs) throws java.io.IOException
reader
- The IndexReader
which will be consulted to identify potential stop words that
exceed the required document frequencymaxPercentDocs
- The maximum percentage (between 0.0 and 1.0) of index documents which
contain a term, after which the word is considered to be a stop word.java.io.IOException
public int addStopWords(IndexReader reader, java.lang.String fieldName, float maxPercentDocs) throws java.io.IOException
reader
- The IndexReader
which will be consulted to identify potential stop words that
exceed the required document frequencyfieldName
- The field for which stopwords will be addedmaxPercentDocs
- The maximum percentage (between 0.0 and 1.0) of index documents which
contain a term, after which the word is considered to be a stop word.java.io.IOException
public int addStopWords(IndexReader reader, java.lang.String fieldName, int maxDocFreq) throws java.io.IOException
reader
- The IndexReader
which will be consulted to identify potential stop words that
exceed the required document frequencyfieldName
- The field for which stopwords will be addedmaxDocFreq
- The maximum number of index documents which
can contain a term, after which the term is considered to be a stop word.java.io.IOException
public TokenStream tokenStream(java.lang.String fieldName, java.io.Reader reader)
Analyzer
tokenStream
in class Analyzer
public TokenStream reusableTokenStream(java.lang.String fieldName, java.io.Reader reader) throws java.io.IOException
Analyzer
reusableTokenStream
in class Analyzer
java.io.IOException
public java.lang.String[] getStopWords(java.lang.String fieldName)
fieldName
- The field for which stop words identified in "addStopWords"
method calls will be returnedpublic Term[] getStopWords()
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