Package org.elasticsearch.index.shard

Class ElasticsearchMergePolicy

java.lang.Object

org.apache.lucene.index.MergePolicy

org.apache.lucene.index.FilterMergePolicy

org.elasticsearch.index.shard.ElasticsearchMergePolicy

public final class ElasticsearchMergePolicy
extends FilterMergePolicy

A MergePolicy that upgrades segments and can upgrade merges.

It can be useful to use the background merging process to upgrade segments, for example when we perform internal changes that imply different index options or when a user modifies his mapping in non-breaking ways: we could imagine using this merge policy to be able to add doc values to fields after the fact or on the opposite to remove them.

For now, this MergePolicy takes care of moving versions that used to be stored as payloads to numeric doc values.

Nested Class Summary

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

MergePolicy.MergeAbortedException, MergePolicy.MergeContext, MergePolicy.MergeException, MergePolicy.MergeSpecification, MergePolicy.OneMerge, MergePolicy.OneMergeProgress

Field Summary

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

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	Description
ElasticsearchMergePolicy(MergePolicy delegate)

Method Summary

Modifier and Type	Method	Description
MergePolicy.MergeSpecification	findForcedMerges(SegmentInfos segmentInfos, int maxSegmentCount, Map<SegmentCommitInfo,Boolean> segmentsToMerge, MergePolicy.MergeContext mergeContext)	Determine what set of merge operations is necessary in order to merge to <= the specified segment count.
void	setUpgradeInProgress(boolean upgrade, boolean onlyAncientSegments)	When upgrade is true, running a force merge will upgrade any segments written with older versions.

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

findForcedDeletesMerges, findMerges, getMaxCFSSegmentSizeMB, getNoCFSRatio, keepFullyDeletedSegment, numDeletesToMerge, setMaxCFSSegmentSizeMB, setNoCFSRatio, size, toString, useCompoundFile

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

assertDelCount, isMerged, message, segString, verbose

Methods inherited from class java.lang.Object

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

Constructor Detail

ElasticsearchMergePolicy

public ElasticsearchMergePolicy(MergePolicy delegate)

Parameters:

delegate - the merge policy to wrap

Method Detail

findForcedMerges

public MergePolicy.MergeSpecification findForcedMerges(SegmentInfos segmentInfos,
                                                       int maxSegmentCount,
                                                       Map<SegmentCommitInfo,Boolean> segmentsToMerge,
                                                       MergePolicy.MergeContext mergeContext)
                                                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 FilterMergePolicy

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.

mergeContext - the IndexWriter to find the merges on

Throws:

IOException

setUpgradeInProgress

public void setUpgradeInProgress(boolean upgrade,
                                 boolean onlyAncientSegments)

When upgrade is true, running a force merge will upgrade any segments written with older versions. This will apply to the next call to IndexWriter.forceMerge(int) that is handled by this MergePolicy, as well as cascading calls made by IndexWriter.