Home » lucene-3.0.1-src » org.apache » lucene » search » [javadoc | source]
org.apache.lucene.search
public final class: NumericRangeQuery [javadoc | source]
java.lang.Object
   org.apache.lucene.search.Query
      org.apache.lucene.search.MultiTermQuery
         org.apache.lucene.search.NumericRangeQuery

All Implemented Interfaces:
    Cloneable, Serializable

A Query that matches numeric values within a specified range. To use this, you must first index the numeric values using NumericField (expert: NumericTokenStream ). If your terms are instead textual, you should use TermRangeQuery . NumericRangeFilter is the filter equivalent of this query.

You create a new NumericRangeQuery with the static factory methods, eg:

Query q = NumericRangeQuery.newFloatRange("weight", 0.3f, 0.10f, true, true);
matches all documents whose float valued "weight" field ranges from 0.3 to 0.10, inclusive.

The performance of NumericRangeQuery is much better than the corresponding TermRangeQuery because the number of terms that must be searched is usually far fewer, thanks to trie indexing, described below.

You can optionally specify a precisionStep when creating this query. This is necessary if you've changed this configuration from its default (4) during indexing. Lower values consume more disk space but speed up searching. Suitable values are between 1 and 8. A good starting point to test is 4, which is the default value for all Numeric* classes. See below for details.

This query defaults to {@linkplain MultiTermQuery#CONSTANT_SCORE_AUTO_REWRITE_DEFAULT} for 32 bit (int/float) ranges with precisionStep ≤8 and 64 bit (long/double) ranges with precisionStep ≤6. Otherwise it uses {@linkplain MultiTermQuery#CONSTANT_SCORE_FILTER_REWRITE} as the number of terms is likely to be high. With precision steps of ≤4, this query can be run with one of the BooleanQuery rewrite methods without changing BooleanQuery's default max clause count.

NOTE: This API is experimental and might change in incompatible ways in the next release.

How it works

See the publication about panFMP, where this algorithm was described (referred to as TrieRangeQuery):

Schindler, U, Diepenbroek, M, 2008. Generic XML-based Framework for Metadata Portals. Computers & Geosciences 34 (12), 1947-1955. doi:10.1016/j.cageo.2008.02.023

A quote from this paper: Because Apache Lucene is a full-text search engine and not a conventional database, it cannot handle numerical ranges (e.g., field value is inside user defined bounds, even dates are numerical values). We have developed an extension to Apache Lucene that stores the numerical values in a special string-encoded format with variable precision (all numerical values like doubles, longs, floats, and ints are converted to lexicographic sortable string representations and stored with different precisions (for a more detailed description of how the values are stored, see NumericUtils ). A range is then divided recursively into multiple intervals for searching: The center of the range is searched only with the lowest possible precision in the trie, while the boundaries are matched more exactly. This reduces the number of terms dramatically.

For the variant that stores long values in 8 different precisions (each reduced by 8 bits) that uses a lowest precision of 1 byte, the index contains only a maximum of 256 distinct values in the lowest precision. Overall, a range could consist of a theoretical maximum of 7*255*2 + 255 = 3825 distinct terms (when there is a term for every distinct value of an 8-byte-number in the index and the range covers almost all of them; a maximum of 255 distinct values is used because it would always be possible to reduce the full 256 values to one term with degraded precision). In practice, we have seen up to 300 terms in most cases (index with 500,000 metadata records and a uniform value distribution).

Precision Step

You can choose any precisionStep when encoding values. Lower step values mean more precisions and so more terms in index (and index gets larger). On the other hand, the maximum number of terms to match reduces, which optimized query speed. The formula to calculate the maximum term count is:

 n = [ (bitsPerValue/precisionStep - 1) * (2^precisionStep - 1 ) * 2 ] + (2^precisionStep - 1 )

(this formula is only correct, when bitsPerValue/precisionStep is an integer; in other cases, the value must be rounded up and the last summand must contain the modulo of the division as precision step). For longs stored using a precision step of 4, n = 15*15*2 + 15 = 465, and for a precision step of 2, n = 31*3*2 + 3 = 189. But the faster search speed is reduced by more seeking in the term enum of the index. Because of this, the ideal precisionStep value can only be found out by testing. Important: You can index with a lower precision step value and test search speed using a multiple of the original step value.

Good values for precisionStep are depending on usage and data type:

Comparisons of the different types of RangeQueries on an index with about 500,000 docs showed that TermRangeQuery in boolean rewrite mode (with raised BooleanQuery clause count) took about 30-40 secs to complete, TermRangeQuery in constant score filter rewrite mode took 5 secs and executing this class took <100ms to complete (on an Opteron64 machine, Java 1.5, 8 bit precision step). This query type was developed for a geographic portal, where the performance for e.g. bounding boxes or exact date/time stamps is important.

Field Summary
 String field     
final  int precisionStep     
final  int valSize     
final  T min     
final  T max     
final  boolean minInclusive     
final  boolean maxInclusive     
Fields inherited from org.apache.lucene.search.MultiTermQuery:
rewriteMethod,  numberOfTerms,  CONSTANT_SCORE_FILTER_REWRITE,  SCORING_BOOLEAN_QUERY_REWRITE,  CONSTANT_SCORE_BOOLEAN_QUERY_REWRITE,  CONSTANT_SCORE_AUTO_REWRITE_DEFAULT
Method from org.apache.lucene.search.NumericRangeQuery Summary:
equals,   getEnum,   getField,   getMax,   getMin,   hashCode,   includesMax,   includesMin,   newDoubleRange,   newDoubleRange,   newFloatRange,   newFloatRange,   newIntRange,   newIntRange,   newLongRange,   newLongRange,   toString
Methods from org.apache.lucene.search.MultiTermQuery:
clearTotalNumberOfTerms,   equals,   getEnum,   getRewriteMethod,   getTotalNumberOfTerms,   hashCode,   incTotalNumberOfTerms,   rewrite,   setRewriteMethod
Methods from org.apache.lucene.search.Query:
clone,   combine,   createWeight,   equals,   extractTerms,   getBoost,   getSimilarity,   hashCode,   mergeBooleanQueries,   rewrite,   setBoost,   toString,   toString,   weight
Methods from java.lang.Object:
clone,   equals,   finalize,   getClass,   hashCode,   notify,   notifyAll,   toString,   wait,   wait,   wait
Method from org.apache.lucene.search.NumericRangeQuery Detail:
 public final boolean equals(Object o) 
 protected FilteredTermEnum getEnum(IndexReader reader) throws IOException 
 public String getField() 
    Returns the field name for this query
 public T getMax() 
    Returns the upper value of this range query
 public T getMin() 
    Returns the lower value of this range query
 public final int hashCode() 
 public boolean includesMax() 
    Returns true if the upper endpoint is inclusive
 public boolean includesMin() 
    Returns true if the lower endpoint is inclusive
 public static NumericRangeQuery<Double> newDoubleRange(String field,
    Double min,
    Double max,
    boolean minInclusive,
    boolean maxInclusive) 
    Factory that creates a NumericRangeQuery, that queries a double range using the default precisionStep NumericUtils#PRECISION_STEP_DEFAULT (4). You can have half-open ranges (which are in fact </≤ or >/≥ queries) by setting the min or max value to null. By setting inclusive to false, it will match all documents excluding the bounds, with inclusive on, the boundaries are hits, too.
 public static NumericRangeQuery<Double> newDoubleRange(String field,
    int precisionStep,
    Double min,
    Double max,
    boolean minInclusive,
    boolean maxInclusive) 
    Factory that creates a NumericRangeQuery, that queries a double range using the given precisionStep. You can have half-open ranges (which are in fact </≤ or >/≥ queries) by setting the min or max value to null. By setting inclusive to false, it will match all documents excluding the bounds, with inclusive on, the boundaries are hits, too.
 public static NumericRangeQuery<Float> newFloatRange(String field,
    Float min,
    Float max,
    boolean minInclusive,
    boolean maxInclusive) 
    Factory that creates a NumericRangeQuery, that queries a float range using the default precisionStep NumericUtils#PRECISION_STEP_DEFAULT (4). You can have half-open ranges (which are in fact </≤ or >/≥ queries) by setting the min or max value to null. By setting inclusive to false, it will match all documents excluding the bounds, with inclusive on, the boundaries are hits, too.
 public static NumericRangeQuery<Float> newFloatRange(String field,
    int precisionStep,
    Float min,
    Float max,
    boolean minInclusive,
    boolean maxInclusive) 
    Factory that creates a NumericRangeQuery, that queries a float range using the given precisionStep. You can have half-open ranges (which are in fact </≤ or >/≥ queries) by setting the min or max value to null. By setting inclusive to false, it will match all documents excluding the bounds, with inclusive on, the boundaries are hits, too.
 public static NumericRangeQuery<Integer> newIntRange(String field,
    Integer min,
    Integer max,
    boolean minInclusive,
    boolean maxInclusive) 
    Factory that creates a NumericRangeQuery, that queries a int range using the default precisionStep NumericUtils#PRECISION_STEP_DEFAULT (4). You can have half-open ranges (which are in fact </≤ or >/≥ queries) by setting the min or max value to null. By setting inclusive to false, it will match all documents excluding the bounds, with inclusive on, the boundaries are hits, too.
 public static NumericRangeQuery<Integer> newIntRange(String field,
    int precisionStep,
    Integer min,
    Integer max,
    boolean minInclusive,
    boolean maxInclusive) 
    Factory that creates a NumericRangeQuery, that queries a int range using the given precisionStep. You can have half-open ranges (which are in fact </≤ or >/≥ queries) by setting the min or max value to null. By setting inclusive to false, it will match all documents excluding the bounds, with inclusive on, the boundaries are hits, too.
 public static NumericRangeQuery<Long> newLongRange(String field,
    Long min,
    Long max,
    boolean minInclusive,
    boolean maxInclusive) 
    Factory that creates a NumericRangeQuery, that queries a long range using the default precisionStep NumericUtils#PRECISION_STEP_DEFAULT (4). You can have half-open ranges (which are in fact </≤ or >/≥ queries) by setting the min or max value to null. By setting inclusive to false, it will match all documents excluding the bounds, with inclusive on, the boundaries are hits, too.
 public static NumericRangeQuery<Long> newLongRange(String field,
    int precisionStep,
    Long min,
    Long max,
    boolean minInclusive,
    boolean maxInclusive) 
    Factory that creates a NumericRangeQuery, that queries a long range using the given precisionStep. You can have half-open ranges (which are in fact </≤ or >/≥ queries) by setting the min or max value to null. By setting inclusive to false, it will match all documents excluding the bounds, with inclusive on, the boundaries are hits, too.
 public String toString(String field)