Apache Lucene的实现

Question

I am reading the source code of Apache Lucene for the past few weeks and trying to figure out the method or the class that is primarily responsible for the writing of the postings lists / index on the disk. I have read much about the indexing and tried to find the point where some method is being called in the process to write the index on the disk but have failed. I know that indices or postings list are written periodically when some internal buffer is full. If anyone has already read the code or know where is it all done, please tell. Thanks

Answer 1

I don't know the answer, however I am very curious about this as well. After not searching too long I came across this on the indexWriter page.

public final void commit() throws IOException Commits all pending changes (added & deleted documents, segment merges, added indexes, etc.) to the index, and syncs all referenced index files, such that a reader will see the changes and the index updates will survive an OS or machine crash or power loss. Note that this does not wait for any running background merges to finish. This may be a costly operation, so you should test the cost in your application and do it only when really necessary.

Note that this operation calls Directory.sync on the index files. That call should not return until the file contents & metadata are on stable storage. For FSDirectory, this calls the OS's fsync. But, beware: some hardware devices may in fact cache writes even during fsync, and return before the bits are actually on stable storage, to give the appearance of faster performance. If you have such a device, and it does not have a battery backup (for example) then on power loss it may still lose data. Lucene cannot guarantee consistency on such devices.

NOTE: if this method hits an OutOfMemoryError you should immediately close the writer. See above for details.

Specified by: commit in interface TwoPhaseCommit Throws: IOException See Also: prepareCommit(), commit(Map)

IndexWriter