Is it possible to iterate through documents stored in Lucene Index?

Question

I have some documents stored in a Lucene index with a docId field. I want to get all docIds stored in the index. There is also a problem. Number of documents is about 300 000 so I would prefer to get this docIds in chunks of size 500. Is it possible to do so?

Answer 1

Document numbers (or ids) will be subsequent numbers from 0 to IndexReader.maxDoc()-1. These numbers are not persistent and are valid only for opened IndexReader. You could check if the document is deleted with IndexReader.isDeleted(int documentNumber) method

Answer 2

IndexReader reader = // create IndexReader
for (int i=0; i<reader.maxDoc(); i++) {
    if (reader.isDeleted(i))
        continue;

    Document doc = reader.document(i);
    String docId = doc.get("docId");

    // do something with docId here...
}