core/org.gnit.lucenekmp.index/DirectoryReader/Companion

Companion

Functions

fun indexExists(directory: Directory): Boolean

Returns true if an index likely exists at the specified directory. Note that if a corrupt index exists, or if an index in the process of committing the return value is not reliable.

listCommits

fun listCommits(dir: Directory): MutableList<IndexCommit>

Returns all commit points that exist in the Directory. Normally, because the default is [ ], there would be only one commit point. But if you're using a custom IndexDeletionPolicy then there could be many commits. Once you have a given commit, you can open a reader on it by calling DirectoryReader.open There must be at least one commit in the Directory, else this method throws [ ]. Note that if a commit is in progress while this method is running, that commit may or may not be returned.

open

fun open(commit: IndexCommit): DirectoryReader

Expert: returns an IndexReader reading the index in the given IndexCommit.

fun open(directory: Directory): DirectoryReader

Returns a IndexReader reading the index in the given Directory

fun open(directory: Directory, leafSorter: Comparator<LeafReader>): DirectoryReader

Returns a IndexReader for the index in the given Directory

fun open(commit: IndexCommit, minSupportedMajorVersion: Int, leafSorter: Comparator<LeafReader>): DirectoryReader

Expert: returns an IndexReader reading the index on the given IndexCommit. This method allows to open indices that were created with a Lucene version older than N-1 provided that all codecs for this index are available in the classpath and the segment file format used was created with Lucene 7 or newer. Users of this API must be aware that Lucene doesn't guarantee semantic compatibility for indices created with versions older than N-1. All backwards compatibility aside from the file format is optional and applied on a best effort basis.

@JvmOverloads

fun open(writer: IndexWriter, applyAllDeletes: Boolean = true, writeAllDeletes: Boolean = false): DirectoryReader

Open a near real time IndexReader from the IndexWriter.

openIfChanged

fun openIfChanged(oldReader: DirectoryReader): DirectoryReader?

If the index has changed since the provided reader was opened, open and return a new reader; else, return null. The new reader, if not null, will be the same type of reader as the previous one, ie an NRT reader will open a new NRT reader etc.

fun openIfChanged(oldReader: DirectoryReader, commit: IndexCommit): DirectoryReader?

If the IndexCommit differs from what the provided reader is searching, open and return a new reader; else, return null.

@JvmOverloads

fun openIfChanged(oldReader: DirectoryReader, writer: IndexWriter, applyAllDeletes: Boolean = true): DirectoryReader?

Expert: If there changes (committed or not) in the IndexWriter versus what the provided reader is searching, then open and return a new IndexReader searching both committed and uncommitted changes from the writer; else, return null (though, the current implementation never returns null).