org.apache.lucene.index

Class UpgradeIndexMergePolicy

java.lang.Object

org.apache.lucene.index.MergePolicy

org.apache.lucene.index.UpgradeIndexMergePolicy

All Implemented Interfaces:

Closeable, Cloneable

public class UpgradeIndexMergePolicy
extends MergePolicy

This MergePolicy is used for upgrading all existing segments of an index when calling IndexWriter.forceMerge(int). All other methods delegate to the base MergePolicy given to the constructor. This allows for an as-cheap-as possible upgrade of an older index by only upgrading segments that are created by previous Lucene versions. forceMerge does no longer really merge; it is just used to "forceMerge" older segment versions away.

In general one would use IndexUpgrader, but for a fully customizeable upgrade, you can use this like any other MergePolicy and call IndexWriter.forceMerge(int):

  IndexWriterConfig iwc = new IndexWriterConfig(Version.LUCENE_XX, new KeywordAnalyzer());
  iwc.setMergePolicy(new UpgradeIndexMergePolicy(iwc.getMergePolicy()));
  IndexWriter w = new IndexWriter(dir, iwc);
  w.forceMerge(1);
  w.close();
 

Warning: This merge policy may reorder documents if the index was partially upgraded before calling forceMerge (e.g., documents were added). If your application relies on "monotonicity" of doc IDs (which means that the order in which the documents were added to the index is preserved), do a forceMerge(1) instead. Please note, the delegate MergePolicy may also reorder documents.

See Also:

IndexUpgrader

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

Nested Class Summary

Nested classes/interfaces inherited from class org.apache.lucene.index.MergePolicy

MergePolicy.MergeAbortedException, MergePolicy.MergeException, MergePolicy.MergeSpecification, MergePolicy.OneMerge

Field Summary

Fields

Modifier and Type	Field and Description
protected MergePolicy	base Wrapped MergePolicy.

Fields inherited from class org.apache.lucene.index.MergePolicy

writer

Constructor Summary

Constructors

Constructor and Description
UpgradeIndexMergePolicy(MergePolicy base) Wrap the given MergePolicy and intercept forceMerge requests to only upgrade segments written with previous Lucene versions.

Method Summary

Methods

Modifier and Type	Method and Description
void	close() Release all resources for the policy.
MergePolicy.MergeSpecification	findForcedDeletesMerges(SegmentInfos segmentInfos) Determine what set of merge operations is necessary in order to expunge all deletes from the index.
MergePolicy.MergeSpecification	findForcedMerges(SegmentInfos segmentInfos, int maxSegmentCount, Map<SegmentInfoPerCommit,Boolean> segmentsToMerge) Determine what set of merge operations is necessary in order to merge to <= the specified segment count.
MergePolicy.MergeSpecification	findMerges(SegmentInfos segmentInfos) Determine what set of merge operations are now necessary on the index.
void	setIndexWriter(IndexWriter writer) Sets the IndexWriter to use by this merge policy.
protected boolean	shouldUpgradeSegment(SegmentInfoPerCommit si) Returns if the given segment should be upgraded.
String	toString()
boolean	useCompoundFile(SegmentInfos segments, SegmentInfoPerCommit newSegment) Returns true if a new segment (regardless of its origin) should use the compound file format.

Methods inherited from class org.apache.lucene.index.MergePolicy

clone

Methods inherited from class java.lang.Object

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

Field Detail

base

protected final MergePolicy base

Wrapped MergePolicy.

Constructor Detail

UpgradeIndexMergePolicy

public UpgradeIndexMergePolicy(MergePolicy base)

Wrap the given MergePolicy and intercept forceMerge requests to only upgrade segments written with previous Lucene versions.

Method Detail

shouldUpgradeSegment

protected boolean shouldUpgradeSegment(SegmentInfoPerCommit si)

Returns if the given segment should be upgraded. The default implementation will return !Constants.LUCENE_MAIN_VERSION.equals(si.getVersion()), so all segments created with a different version number than this Lucene version will get upgraded.

setIndexWriter

public void setIndexWriter(IndexWriter writer)

Description copied from class: MergePolicy

Sets the IndexWriter to use by this merge policy. This method is allowed to be called only once, and is usually set by IndexWriter. If it is called more than once, SetOnce.AlreadySetException is thrown.

Overrides:

setIndexWriter in class MergePolicy

See Also:

SetOnce

findMerges

public MergePolicy.MergeSpecification findMerges(SegmentInfos segmentInfos)
                                          throws IOException

Description copied from class: MergePolicy

Determine what set of merge operations are now necessary on the index. IndexWriter calls this whenever there is a change to the segments. This call is always synchronized on the IndexWriter instance so only one thread at a time will call this method.

Specified by:

findMerges in class MergePolicy

Parameters:

segmentInfos - the total set of segments in the index

Throws:

IOException

findForcedMerges

public MergePolicy.MergeSpecification findForcedMerges(SegmentInfos segmentInfos,
                                              int maxSegmentCount,
                                              Map<SegmentInfoPerCommit,Boolean> segmentsToMerge)
                                                throws IOException

Description copied from class: MergePolicy

Determine what set of merge operations is necessary in order to merge to <= the specified segment count. IndexWriter calls this when its IndexWriter.forceMerge(int) method is called. This call is always synchronized on the IndexWriter instance so only one thread at a time will call this method.

Specified by:

findForcedMerges in class MergePolicy

Parameters:

segmentInfos - the total set of segments in the index

maxSegmentCount - requested maximum number of segments in the index (currently this is always 1)

segmentsToMerge - contains the specific SegmentInfo instances that must be merged away. This may be a subset of all SegmentInfos. If the value is True for a given SegmentInfo, that means this segment was an original segment present in the to-be-merged index; else, it was a segment produced by a cascaded merge.

Throws:

IOException

findForcedDeletesMerges

public MergePolicy.MergeSpecification findForcedDeletesMerges(SegmentInfos segmentInfos)
                                                       throws IOException

Description copied from class: MergePolicy

Determine what set of merge operations is necessary in order to expunge all deletes from the index.

Specified by:

findForcedDeletesMerges in class MergePolicy

Parameters:

segmentInfos - the total set of segments in the index

Throws:

IOException

useCompoundFile

public boolean useCompoundFile(SegmentInfos segments,
                      SegmentInfoPerCommit newSegment)
                        throws IOException

Description copied from class: MergePolicy

Returns true if a new segment (regardless of its origin) should use the compound file format.

Specified by:

useCompoundFile in class MergePolicy

Throws:

IOException

close

public void close()

Description copied from class: MergePolicy

Release all resources for the policy.

Specified by:

close in interface Closeable

Specified by:

close in class MergePolicy

toString

public String toString()

Overrides:

toString in class Object