Delete all documents from index using ElasticsearchOperations

Question

I'm trying to delete all the documents from particular index of ES using the following code:

@Autowired
protected ElasticsearchOperations elasticsearchOperations;

@BeforeEach
void beforeEach() {
    Query query = new NativeSearchQueryBuilder().withQuery(matchAllQuery()).build();
    elasticsearchOperations.delete(query, elasticsearchOperations.getIndexCoordinatesFor(ReviewRequestDocument.class));
}

which fails with

java.lang.IllegalArgumentException: id must not be null

I'm puzzled, because similar approach works for counting documents in index:

private long countReviewRequestDocuments() {
    Query query = new NativeSearchQueryBuilder().withQuery(matchAllQuery()).build();
    return elasticsearchOperations.count(query, ReviewRequestDocument.class);
}

So my question is what is the correct way to remove all documents from index?

Answer 1

I've found the solution:

@BeforeEach
void beforeEach() {
  IndexCoordinates coordinates = elasticsearchOperations.getIndexCoordinatesFor(ReviewRequestDocument.class);

  Query query = new NativeSearchQueryBuilder().withQuery(matchAllQuery()).build();
  String[] ids = elasticsearchOperations.search(query, ReviewRequestDocument.class, coordinates)
          .stream()
          .map(SearchHit::getId)
          .toArray(String[]::new);

  Query idsQuery = new NativeSearchQueryBuilder().withQuery(idsQuery().addIds(ids)).build();
  elasticsearchOperations.delete(idsQuery, ReviewRequestDocument.class, coordinates);

  assertThat(countReviewRequestDocuments()).isZero();
}

it looks like ES does not allow bulk removal of all documents in index, so the solution is to fetch ids and then pass them into delete query.