org.apache.lucene.index

Class UpgradeIndexMergePolicy

java.lang.Object

org.apache.lucene.index.MergePolicy

org.apache.lucene.index.MergePolicyWrapper

org.apache.lucene.index.UpgradeIndexMergePolicy

public class UpgradeIndexMergePolicy
extends MergePolicyWrapper

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, MergePolicy.OneMergeProgress

Field Summary

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

in

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

DEFAULT_MAX_CFS_SEGMENT_SIZE, DEFAULT_NO_CFS_RATIO, maxCFSSegmentSize, noCFSRatio

Constructor Summary

Constructors

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

Method Summary

Modifier and Type	Method and Description
MergePolicy.MergeSpecification	findForcedMerges(SegmentInfos segmentInfos, int maxSegmentCount, Map<SegmentCommitInfo,Boolean> segmentsToMerge, IndexWriter writer) Determine what set of merge operations is necessary in order to merge to <= the specified segment count.
MergePolicy.MergeSpecification	findMerges(MergeTrigger mergeTrigger, SegmentInfos segmentInfos, IndexWriter writer) Determine what set of merge operations are now necessary on the index.
protected boolean	shouldUpgradeSegment(SegmentCommitInfo si) Returns if the given segment should be upgraded.

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

findForcedDeletesMerges, getNoCFSRatio, setMaxCFSSegmentSizeMB, setNoCFSRatio, size, toString, useCompoundFile

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

getMaxCFSSegmentSizeMB, isMerged

Methods inherited from class java.lang.Object

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

Constructor Detail

UpgradeIndexMergePolicy

public UpgradeIndexMergePolicy(MergePolicy in)

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

Method Detail

shouldUpgradeSegment

protected boolean shouldUpgradeSegment(SegmentCommitInfo si)

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

findMerges

public MergePolicy.MergeSpecification findMerges(MergeTrigger mergeTrigger,
                                                 SegmentInfos segmentInfos,
                                                 IndexWriter writer)
                                          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.

Overrides:

findMerges in class MergePolicyWrapper

Parameters:

mergeTrigger - the event that triggered the merge

segmentInfos - the total set of segments in the index

writer - the IndexWriter to find the merges on

Throws:

IOException

findForcedMerges

public MergePolicy.MergeSpecification findForcedMerges(SegmentInfos segmentInfos,
                                                       int maxSegmentCount,
                                                       Map<SegmentCommitInfo,Boolean> segmentsToMerge,
                                                       IndexWriter writer)
                                                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.

Overrides:

findForcedMerges in class MergePolicyWrapper

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.

writer - the IndexWriter to find the merges on

Throws:

IOException