Package org.apache.lucene.search.comparators

Class TermOrdValComparator

java.lang.Object

org.apache.lucene.search.FieldComparator<BytesRef>

org.apache.lucene.search.comparators.TermOrdValComparator

public class TermOrdValComparator
extends FieldComparator<BytesRef>

Sorts by field's natural Term sort order, using ordinals. This is functionally equivalent to FieldComparator.TermValComparator, but it first resolves the string to their relative ordinal positions (using the index returned by LeafReader.getSortedDocValues(String)), and does most comparisons using the ordinals. For medium to large results, this comparator will be much faster than FieldComparator.TermValComparator. For very small result sets it may be slower.

Nested Class Summary

Nested classes/interfaces inherited from class org.apache.lucene.search.FieldComparator

FieldComparator.RelevanceComparator, FieldComparator.TermValComparator

Constructor Summary

Constructors

Constructor	Description
TermOrdValComparator(int numHits, String field, boolean sortMissingLast, boolean reverse, boolean enableSkipping)	Creates this, with control over how missing values are sorted.

Method Summary

Modifier and Type	Method	Description
int	compare(int slot1, int slot2)	Compare hit at slot1 with hit at slot2.
int	compareValues(BytesRef val1, BytesRef val2)	Returns a negative integer if first is less than second, 0 if they are equal and a positive integer otherwise.
void	disableSkipping()	Informs the comparator that the skipping of documents should be disabled.
LeafFieldComparator	getLeafComparator(LeafReaderContext context)	Get a per-segment LeafFieldComparator to collect the given LeafReaderContext.
protected SortedDocValues	getSortedDocValues(LeafReaderContext context, String field)	Retrieves the SortedDocValues for the field in this segment
void	setSingleSort()	Informs the comparator that sort is done on this single field.
void	setTopValue(BytesRef value)	Record the top value, for future calls to LeafFieldComparator.compareTop(int).
BytesRef	value(int slot)	Return the actual value in the slot.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

TermOrdValComparator

public TermOrdValComparator(int numHits,
                            String field,
                            boolean sortMissingLast,
                            boolean reverse,
                            boolean enableSkipping)

Creates this, with control over how missing values are sorted. Pass sortMissingLast=true to put missing values at the end.

Method Detail

disableSkipping

public void disableSkipping()

Description copied from class: FieldComparator

Informs the comparator that the skipping of documents should be disabled. This function is called by TopFieldCollector in cases when the skipping functionality should not be applied or not necessary. An example could be when search sort is a part of the index sort, and can be already efficiently handled by TopFieldCollector, and doing extra work for skipping in the comparator is redundant.

Overrides:

disableSkipping in class FieldComparator<BytesRef>

setSingleSort

public void setSingleSort()

Description copied from class: FieldComparator

Informs the comparator that sort is done on this single field. This is useful to enable some optimizations for skipping non-competitive documents.

Overrides:

setSingleSort in class FieldComparator<BytesRef>

compare

public int compare(int slot1,
                   int slot2)

Description copied from class: FieldComparator

Compare hit at slot1 with hit at slot2.

Specified by:

compare in class FieldComparator<BytesRef>

Parameters:

slot1 - first slot to compare

slot2 - second slot to compare

Returns:

any N < 0 if slot2's value is sorted after slot1, any N > 0 if the slot2's value is sorted before slot1 and 0 if they are equal

getSortedDocValues

protected SortedDocValues getSortedDocValues(LeafReaderContext context,
                                             String field)
                                      throws IOException

Retrieves the SortedDocValues for the field in this segment

Throws:

IOException

getLeafComparator

public LeafFieldComparator getLeafComparator(LeafReaderContext context)
                                      throws IOException

Description copied from class: FieldComparator

Get a per-segment LeafFieldComparator to collect the given LeafReaderContext. All docIDs supplied to this LeafFieldComparator are relative to the current reader (you must add docBase if you need to map it to a top-level docID).

Specified by:

getLeafComparator in class FieldComparator<BytesRef>

Parameters:

context - current reader context

Returns:

the comparator to use for this segment

Throws:

IOException - if there is a low-level IO error

setTopValue

public void setTopValue(BytesRef value)

Description copied from class: FieldComparator

Record the top value, for future calls to LeafFieldComparator.compareTop(int). This is only called for searches that use searchAfter (deep paging), and is called before any calls to FieldComparator.getLeafComparator(LeafReaderContext).

Specified by:

setTopValue in class FieldComparator<BytesRef>

value

public BytesRef value(int slot)

Description copied from class: FieldComparator

Return the actual value in the slot.

Specified by:

value in class FieldComparator<BytesRef>

Parameters:

slot - the value

Returns:

value in this slot

compareValues

public int compareValues(BytesRef val1,
                         BytesRef val2)

Description copied from class: FieldComparator

Returns a negative integer if first is less than second, 0 if they are equal and a positive integer otherwise. Default impl to assume the type implements Comparable and invoke .compareTo; be sure to override this method if your FieldComparator's type isn't a Comparable or if your values may sometimes be null

Overrides:

compareValues in class FieldComparator<BytesRef>