Class UpgradeIndexMergePolicy

This MergePolicy is used for upgrading all existing segments of an index when calling 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 ForceMerge(int): 
IndexWriterConfig iwc = new IndexWriterConfig(LuceneVersion.LUCENE_XX, new KeywordAnalyzer());
iwc.MergePolicy = new UpgradeIndexMergePolicy(iwc.MergePolicy);
using (IndexWriter w = new IndexWriter(dir, iwc))
{
    w.ForceMerge(1);
}

Warning: this merge policy may reorder documents if the index was partially upgraded before calling ForceMerge(int) (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.

Note

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

Inheritance
object
MergePolicy
UpgradeIndexMergePolicy
Implements
Inherited Members
Namespace: Lucene.Net.Index
Assembly: Lucene.Net.dll
Syntax
public class UpgradeIndexMergePolicy : MergePolicy, IDisposable

Constructors

UpgradeIndexMergePolicy(MergePolicy)

Wrap the given MergePolicy and intercept ForceMerge(int) requests to only upgrade segments written with previous Lucene versions.

Declaration
public UpgradeIndexMergePolicy(MergePolicy @base)
Parameters
Type Name Description
MergePolicy base
See Also

Fields

m_base

Wrapped MergePolicy.

Declaration
protected readonly MergePolicy m_base
Field Value
Type Description
MergePolicy
See Also

Methods

Dispose(bool)

Release all resources for the policy.

Declaration
protected override void Dispose(bool disposing)
Parameters
Type Name Description
bool disposing
Overrides
See Also

FindForcedDeletesMerges(SegmentInfos)

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

Declaration
public override MergePolicy.MergeSpecification FindForcedDeletesMerges(SegmentInfos segmentInfos)
Parameters
Type Name Description
SegmentInfos segmentInfos

the total set of segments in the index
Returns
Type Description
MergePolicy.MergeSpecification
Overrides
See Also

FindForcedMerges(SegmentInfos, int, IDictionary<SegmentCommitInfo, bool>)

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

Declaration
public override MergePolicy.MergeSpecification FindForcedMerges(SegmentInfos segmentInfos, int maxSegmentCount, IDictionary<SegmentCommitInfo, bool> segmentsToMerge)
Parameters
Type Name Description
SegmentInfos segmentInfos

The total set of segments in the index
int maxSegmentCount

Requested maximum number of segments in the index (currently this is always 1)
IDictionary<SegmentCommitInfo, bool> 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.
Returns
Type Description
MergePolicy.MergeSpecification
Overrides
See Also

FindMerges(MergeTrigger, SegmentInfos)

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.

Declaration
public override MergePolicy.MergeSpecification FindMerges(MergeTrigger mergeTrigger, SegmentInfos segmentInfos)
Parameters
Type Name Description
MergeTrigger mergeTrigger

the event that triggered the merge
SegmentInfos segmentInfos

the total set of segments in the index
Returns
Type Description
MergePolicy.MergeSpecification
Overrides
See Also

SetIndexWriter(IndexWriter)

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, AlreadySetException is thrown.

Declaration
public override void SetIndexWriter(IndexWriter writer)
Parameters
Type Name Description
IndexWriter writer
Overrides
See Also

ShouldUpgradeSegment(SegmentCommitInfo)

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

Declaration
protected virtual bool ShouldUpgradeSegment(SegmentCommitInfo si)
Parameters
Type Name Description
SegmentCommitInfo si
Returns
Type Description
bool
See Also

ToString()

Returns a string that represents the current object.

Declaration
public override string ToString()
Returns
Type Description
string

A string that represents the current object.
Overrides
See Also

UseCompoundFile(SegmentInfos, SegmentCommitInfo)

Returns true if a new segment (regardless of its origin) should use the compound file format. The default implementation returns true iff the size of the given mergedInfo is less or equal to MaxCFSSegmentSizeMB and the size is less or equal to the TotalIndexSize * NoCFSRatio otherwise 

false
.
Declaration
public override bool UseCompoundFile(SegmentInfos segments, SegmentCommitInfo newSegment)
Parameters
Type Name Description
SegmentInfos segments
SegmentCommitInfo newSegment
Returns
Type Description
bool
Overrides
See Also

Implements

See Also