Module org.apache.lucene.core
Package org.apache.lucene.index
Class PersistentSnapshotDeletionPolicy
java.lang.Object
org.apache.lucene.index.IndexDeletionPolicy
org.apache.lucene.index.SnapshotDeletionPolicy
org.apache.lucene.index.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 PersistentSnapshotDeletionPolicy
s that write to the same
directory across IndexWriter
s 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(long)
method to release commits from a previous snapshot's
IndexCommit.getGeneration()
.
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Field Summary
FieldsModifier and TypeFieldDescriptionprivate static final String
private final Directory
private long
static final String
Prefix used for the save file.private static final int
private static final int
Fields inherited from class org.apache.lucene.index.SnapshotDeletionPolicy
indexCommits, lastCommit, refCounts
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Constructor Summary
ConstructorsConstructorDescriptionPersistentSnapshotDeletionPolicy
(IndexDeletionPolicy primary, Directory dir) PersistentSnapshotDeletionPolicy
wraps anotherIndexDeletionPolicy
to enable flexible snapshotting, passingIndexWriterConfig.OpenMode.CREATE_OR_APPEND
by default.PersistentSnapshotDeletionPolicy
(IndexDeletionPolicy primary, Directory dir, IndexWriterConfig.OpenMode mode) PersistentSnapshotDeletionPolicy
wraps anotherIndexDeletionPolicy
to enable flexible snapshotting. -
Method Summary
Modifier and TypeMethodDescriptionprivate void
Returns the file name the snapshots are currently saved to, or null if no snapshots have been saved.private void
Reads the snapshots information from the givenDirectory
.private void
persist()
void
release
(long gen) Deletes a snapshotted commit by generation.void
release
(IndexCommit commit) Deletes a snapshotted commit.snapshot()
Snapshots the last commit.Methods inherited from class org.apache.lucene.index.SnapshotDeletionPolicy
getIndexCommit, getSnapshotCount, getSnapshots, incRef, onCommit, onInit, releaseGen
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Field Details
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SNAPSHOTS_PREFIX
Prefix used for the save file.- See Also:
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VERSION_START
private static final int VERSION_START- See Also:
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VERSION_CURRENT
private static final int VERSION_CURRENT- See Also:
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CODEC_NAME
- See Also:
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nextWriteGen
private long nextWriteGen -
dir
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Constructor Details
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PersistentSnapshotDeletionPolicy
public PersistentSnapshotDeletionPolicy(IndexDeletionPolicy primary, Directory dir) throws IOException PersistentSnapshotDeletionPolicy
wraps anotherIndexDeletionPolicy
to enable flexible snapshotting, passingIndexWriterConfig.OpenMode.CREATE_OR_APPEND
by default.- Parameters:
primary
- theIndexDeletionPolicy
that is used on non-snapshotted commits. Snapshotted commits, by definition, are not deleted until explicitly released viarelease(org.apache.lucene.index.IndexCommit)
.dir
- theDirectory
which will be used to persist the snapshots information.- Throws:
IOException
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PersistentSnapshotDeletionPolicy
public PersistentSnapshotDeletionPolicy(IndexDeletionPolicy primary, Directory dir, IndexWriterConfig.OpenMode mode) throws IOException PersistentSnapshotDeletionPolicy
wraps anotherIndexDeletionPolicy
to enable flexible snapshotting.- Parameters:
primary
- theIndexDeletionPolicy
that is used on non-snapshotted commits. Snapshotted commits, by definition, are not deleted until explicitly released viarelease(org.apache.lucene.index.IndexCommit)
.dir
- theDirectory
which will be used to persist the snapshots information.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.- Throws:
IOException
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Method Details
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snapshot
Snapshots the last commit. Once this method returns, the snapshot information is persisted in the directory.- Overrides:
snapshot
in classSnapshotDeletionPolicy
- Returns:
- the
IndexCommit
that was snapshotted. - Throws:
IOException
- See Also:
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release
Deletes a snapshotted commit. Once this method returns, the snapshot information is persisted in the directory.- Overrides:
release
in classSnapshotDeletionPolicy
- Parameters:
commit
- the commit previously returned bySnapshotDeletionPolicy.snapshot()
- Throws:
IOException
- See Also:
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release
Deletes a snapshotted commit by generation. Once this method returns, the snapshot information is persisted in the directory.- Throws:
IOException
- See Also:
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persist
- Throws:
IOException
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clearPriorSnapshots
- Throws:
IOException
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getLastSaveFile
Returns the file name the snapshots are currently saved to, or null if no snapshots have been saved. -
loadPriorSnapshots
Reads the snapshots information from the givenDirectory
. This method can be used if the snapshots information is needed, however you cannot instantiate the deletion policy (because e.g., some other process keeps a lock on the snapshots directory).- Throws:
IOException
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