Class PersistentSnapshotDeletionPolicy

A SnapshotDeletionPolicy which adds a persistence layer so that snapshots can be maintained across the life of an application. The snapshots are persisted in a Directory and are committed as soon as Snapshot() or Release(IndexCommit) is called.

NOTE: Sharing PersistentSnapshotDeletionPolicys that write to the same directory across IndexWriters will corrupt snapshots. You should make sure every IndexWriter has its own PersistentSnapshotDeletionPolicy and that they all write to a different Directory. It is OK to use the same Directory that holds the index.

This class adds a Release(Int64) method to release commits from a previous snapshot's Generation.

This is a Lucene.NET EXPERIMENTAL API, use at your own risk
Inheritance
System.Object
IndexDeletionPolicy
SnapshotDeletionPolicy
PersistentSnapshotDeletionPolicy
Inherited Members
Namespace: Lucene.Net.Index
Assembly: Lucene.Net.dll
Syntax
public class PersistentSnapshotDeletionPolicy : SnapshotDeletionPolicy

Constructors

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PersistentSnapshotDeletionPolicy(IndexDeletionPolicy, Directory)

PersistentSnapshotDeletionPolicy wraps another IndexDeletionPolicy to enable flexible snapshotting, passing CREATE_OR_APPEND by default.

Declaration
public PersistentSnapshotDeletionPolicy(IndexDeletionPolicy primary, Directory dir)
Parameters
Type Name Description
IndexDeletionPolicy primary

the IndexDeletionPolicy that is used on non-snapshotted commits. Snapshotted commits, by definition, are not deleted until explicitly released via Release(IndexCommit).

Directory dir

the Directory which will be used to persist the snapshots information.

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PersistentSnapshotDeletionPolicy(IndexDeletionPolicy, Directory, OpenMode)

PersistentSnapshotDeletionPolicy wraps another IndexDeletionPolicy to enable flexible snapshotting.

Declaration
public PersistentSnapshotDeletionPolicy(IndexDeletionPolicy primary, Directory dir, OpenMode mode)
Parameters
Type Name Description
IndexDeletionPolicy primary

the IndexDeletionPolicy that is used on non-snapshotted commits. Snapshotted commits, by definition, are not deleted until explicitly released via Release(IndexCommit).

Directory dir

the Directory which will be used to persist the snapshots information.

OpenMode mode

specifies whether a new index should be created, deleting all existing snapshots information (immediately), or open an existing index, initializing the class with the snapshots information.

Fields

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SNAPSHOTS_PREFIX

Prefix used for the save file.

Declaration
public static readonly string SNAPSHOTS_PREFIX
Field Value
Type Description
System.String

Properties

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LastSaveFile

Returns the file name the snapshots are currently saved to, or null if no snapshots have been saved.

Declaration
public virtual string LastSaveFile { get; }
Property Value
Type Description
System.String

Methods

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Release(IndexCommit)

Deletes a snapshotted commit. Once this method returns, the snapshot information is persisted in the directory.

Declaration
public override void Release(IndexCommit commit)
Parameters
Type Name Description
IndexCommit commit
Overrides
See Also
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Release(Int64)

Deletes a snapshotted commit by generation. Once this method returns, the snapshot information is persisted in the directory.

Declaration
public virtual void Release(long gen)
Parameters
Type Name Description
System.Int64 gen
See Also
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Snapshot()

Snapshots the last commit. Once this method returns, the snapshot information is persisted in the directory.

Declaration
public override IndexCommit Snapshot()
Returns
Type Description
IndexCommit
Overrides
See Also