This class provides a {@link Field} that enables indexing - * of numeric values for efficient range filtering and - * sorting. Here's an example usage, adding an int value: - *
- * document.add(new NumericField(name).setIntValue(value)); - *- * - * For optimal performance, re-use the - *
NumericField and {@link Document} instance for more than
- * one document:
- *
- *
- * NumericField field = new NumericField(name);
- * Document document = new Document();
- * document.add(field);
- *
- * for(all documents) {
- * ...
- * field.setIntValue(value)
- * writer.addDocument(document);
- * ...
- * }
- *
- *
- * The java native types int, long,
- * float and double are
- * directly supported. However, any value that can be
- * converted into these native types can also be indexed.
- * For example, date/time values represented by a
- * {@link java.util.Date} can be translated into a long
- * value using the {@link java.util.Date#getTime} method. If you
- * don't need millisecond precision, you can quantize the
- * value, either by dividing the result of
- * {@link java.util.Date#getTime} or using the separate getters
- * (for year, month, etc.) to construct an int or
- * long value.
To perform range querying or filtering against a
- * NumericField, use {@link NumericRangeQuery} or {@link
- * NumericRangeFilter}. To sort according to a
- * NumericField, use the normal numeric sort types, eg
- * {@link SortField#INT}. NumericField values
- * can also be loaded directly from {@link FieldCache}.
By default, a NumericField's value is not stored but
- * is indexed for range filtering and sorting. You can use
- * the {@link #NumericField(String,Field.Store,boolean)}
- * constructor if you need to change these defaults.
You may add the same field name as a NumericField to
- * the same document more than once. Range querying and
- * filtering will be the logical OR of all values; so a range query
- * will hit all documents that have at least one value in
- * the range. However sort behavior is not defined. If you need to sort,
- * you should separately index a single-valued NumericField.
A NumericField will consume somewhat more disk space
- * in the index than an ordinary single-valued field.
- * However, for a typical index that includes substantial
- * textual content per document, this increase will likely
- * be in the noise.
Within Lucene, each numeric value is indexed as a
- * trie structure, where each term is logically
- * assigned to larger and larger pre-defined brackets (which
- * are simply lower-precision representations of the value).
- * The step size between each successive bracket is called the
- * precisionStep, measured in bits. Smaller
- * precisionStep values result in larger number
- * of brackets, which consumes more disk space in the index
- * but may result in faster range search performance. The
- * default value, 4, was selected for a reasonable tradeoff
- * of disk space consumption versus performance. You can
- * use the expert constructor {@link
- * #NumericField(String,int,Field.Store,boolean)} if you'd
- * like to change the value. Note that you must also
- * specify a congruent value when creating {@link
- * NumericRangeQuery} or {@link NumericRangeFilter}.
- * For low cardinality fields larger precision steps are good.
- * If the cardinality is < 100, it is fair
- * to use {@link Integer#MAX_VALUE}, which produces one
- * term per value.
- *
- *
For more information on the internals of numeric trie
- * indexing, including the precisionStep
- * configuration, see {@link NumericRangeQuery}. The format of
- * indexed values is described in {@link NumericUtils}.
- *
- *
If you only need to sort by numeric value, and never
- * run range querying/filtering, you can index using a
- * precisionStep of {@link Integer#MAX_VALUE}.
- * This will minimize disk space consumed.
More advanced users can instead use {@link - * NumericTokenStream} directly, when indexing numbers. This - * class is a wrapper around this token stream type for - * easier, more intuitive usage.
- * - * @since 2.9 - */ -public final class NumericField extends AbstractField { - - /** Data type of the value in {@link NumericField}. - * @since 3.2 - */ - public static enum DataType { INT, LONG, FLOAT, DOUBLE } - - private transient NumericTokenStream numericTS; - private DataType type; - private final int precisionStep; - - /** - * Creates a field for numeric values using the defaultprecisionStep
- * {@link NumericUtils#PRECISION_STEP_DEFAULT} (4). The instance is not yet initialized with
- * a numeric value, before indexing a document containing this field,
- * set a value using the various set???Value() methods.
- * This constructor creates an indexed, but not stored field.
- * @param name the field name
- */
- public NumericField(String name) {
- this(name, NumericUtils.PRECISION_STEP_DEFAULT, Field.Store.NO, true);
- }
-
- /**
- * Creates a field for numeric values using the default precisionStep
- * {@link NumericUtils#PRECISION_STEP_DEFAULT} (4). The instance is not yet initialized with
- * a numeric value, before indexing a document containing this field,
- * set a value using the various set???Value() methods.
- * @param name the field name
- * @param store if the field should be stored, {@link Document#getFieldable}
- * then returns {@code NumericField} instances on search results.
- * @param index if the field should be indexed using {@link NumericTokenStream}
- */
- public NumericField(String name, Field.Store store, boolean index) {
- this(name, NumericUtils.PRECISION_STEP_DEFAULT, store, index);
- }
-
- /**
- * Creates a field for numeric values with the specified
- * precisionStep. The instance is not yet initialized with
- * a numeric value, before indexing a document containing this field,
- * set a value using the various set???Value() methods.
- * This constructor creates an indexed, but not stored field.
- * @param name the field name
- * @param precisionStep the used precision step
- */
- public NumericField(String name, int precisionStep) {
- this(name, precisionStep, Field.Store.NO, true);
- }
-
- /**
- * Creates a field for numeric values with the specified
- * precisionStep. The instance is not yet initialized with
- * a numeric value, before indexing a document containing this field,
- * set a value using the various set???Value() methods.
- * @param name the field name
- * @param precisionStep the used precision step
- * @param store if the field should be stored, {@link Document#getFieldable}
- * then returns {@code NumericField} instances on search results.
- * @param index if the field should be indexed using {@link NumericTokenStream}
- */
- public NumericField(String name, int precisionStep, Field.Store store, boolean index) {
- super(name, store, index ? Field.Index.ANALYZED_NO_NORMS : Field.Index.NO, Field.TermVector.NO);
- this.precisionStep = precisionStep;
- setIndexOptions(IndexOptions.DOCS_ONLY);
- }
-
- /** Returns a {@link NumericTokenStream} for indexing the numeric value. */
- public TokenStream tokenStreamValue() {
- if (!isIndexed())
- return null;
- if (numericTS == null) {
- // lazy init the TokenStream as it is heavy to instantiate (attributes,...),
- // if not needed (stored field loading)
- numericTS = new NumericTokenStream(precisionStep);
- // initialize value in TokenStream
- if (fieldsData != null) {
- assert type != null;
- final Number val = (Number) fieldsData;
- switch (type) {
- case INT:
- numericTS.setIntValue(val.intValue()); break;
- case LONG:
- numericTS.setLongValue(val.longValue()); break;
- case FLOAT:
- numericTS.setFloatValue(val.floatValue()); break;
- case DOUBLE:
- numericTS.setDoubleValue(val.doubleValue()); break;
- default:
- assert false : "Should never get here";
- }
- }
- }
- return numericTS;
- }
-
- /** Returns always null for numeric fields */
- @Override
- public byte[] getBinaryValue(byte[] result){
- return null;
- }
-
- /** Returns always null for numeric fields */
- public Reader readerValue() {
- return null;
- }
-
- /** Returns the numeric value as a string. This format is also returned if you call {@link Document#get(String)}
- * on search results. It is recommended to use {@link Document#getFieldable} instead
- * that returns {@code NumericField} instances. You can then use {@link #getNumericValue}
- * to return the stored value. */
- public String stringValue() {
- return (fieldsData == null) ? null : fieldsData.toString();
- }
-
- /** Returns the current numeric value as a subclass of {@link Number}, null if not yet initialized. */
- public Number getNumericValue() {
- return (Number) fieldsData;
- }
-
- /** Returns the precision step. */
- public int getPrecisionStep() {
- return precisionStep;
- }
-
- /** Returns the data type of the current value, {@code null} if not yet set.
- * @since 3.2
- */
- public DataType getDataType() {
- return type;
- }
-
- /**
- * Initializes the field with the supplied long value.
- * @param value the numeric value
- * @return this instance, because of this you can use it the following way:
- * document.add(new NumericField(name, precisionStep).setLongValue(value))
- */
- public NumericField setLongValue(final long value) {
- if (numericTS != null) numericTS.setLongValue(value);
- fieldsData = Long.valueOf(value);
- type = DataType.LONG;
- return this;
- }
-
- /**
- * Initializes the field with the supplied int value.
- * @param value the numeric value
- * @return this instance, because of this you can use it the following way:
- * document.add(new NumericField(name, precisionStep).setIntValue(value))
- */
- public NumericField setIntValue(final int value) {
- if (numericTS != null) numericTS.setIntValue(value);
- fieldsData = Integer.valueOf(value);
- type = DataType.INT;
- return this;
- }
-
- /**
- * Initializes the field with the supplied double value.
- * @param value the numeric value
- * @return this instance, because of this you can use it the following way:
- * document.add(new NumericField(name, precisionStep).setDoubleValue(value))
- */
- public NumericField setDoubleValue(final double value) {
- if (numericTS != null) numericTS.setDoubleValue(value);
- fieldsData = Double.valueOf(value);
- type = DataType.DOUBLE;
- return this;
- }
-
- /**
- * Initializes the field with the supplied float value.
- * @param value the numeric value
- * @return this instance, because of this you can use it the following way:
- * document.add(new NumericField(name, precisionStep).setFloatValue(value))
- */
- public NumericField setFloatValue(final float value) {
- if (numericTS != null) numericTS.setFloatValue(value);
- fieldsData = Float.valueOf(value);
- type = DataType.FLOAT;
- return this;
- }
-
-}