java - Elasticsearch 使用 RestHighLevelClient 设置限制和偏移量

Question

我使用 MultiSearchRequest 按字段的一部分在 Elasticsearch 中进行搜索:

@Override
public Collection<Map<String, Object>> findContractsByIndexAndWord(String index, String type, String word) throws CommonUserException {
    MultiSearchRequest request = new MultiSearchRequest();
    word = word.toLowerCase();
    request.add(formSearchRequestForMultiSearch(index, type, ID_FIELD, word));
    request.add(formSearchRequestForMultiSearch(index, type, PROVIDER_ID_FIELD, word));

    MultiSearchResponse searchResponse;
    try (RestHighLevelClient client = getClient()) {
        searchResponse = client.multiSearch(request);
        return formContracts(searchResponse);
    } catch (IOException e) {
        throw new CommonUserException(ELASTIC_EXCEPTION, ELASTIC_EXCEPTION);
    }
}

private SearchRequest formSearchRequestForMultiSearch(String index, String type, String field, String word) {
    SearchRequest searchRequest = new SearchRequest(index);
    searchRequest.types(type);
    SearchSourceBuilder searchSourceBuilder = new SearchSourceBuilder();
    searchSourceBuilder.query(QueryBuilders.wildcardQuery(field, word));
    searchRequest.source(searchSourceBuilder);
    return searchRequest;
}
private Collection<Map<String, Object>> formContracts(MultiSearchResponse response) {
    Collection<Map<String, Object>> contracts = new LinkedList<>();
    for (int i = 0; i < response.getResponses().length; i++) {
        SearchHit[] hits = response.getResponses()[i].getResponse().getHits().getHits();
        for (SearchHit hit : hits) {
            if (!contracts.contains(hit.getSourceAsMap())) {
                contracts.add(hit.getSourceAsMap());
            }
        }
    }
    return contracts;
}

如何添加此请求限制和结果偏移？

Answer 1

来自elasticsearch documentation (最新版本)

Here are a few examples of some common options:

SearchSourceBuilder sourceBuilder = new SearchSourceBuilder();  //1
sourceBuilder.query(QueryBuilders.termQuery("user", "kimchy"));   //2
sourceBuilder.from(0);                                            //3
sourceBuilder.size(5);                                            //4
sourceBuilder.timeout(new TimeValue(60, TimeUnit.SECONDS));       //5

1. Create a SearchSourceBuilder with default options.
2. Set the query. Can be any type of QueryBuilder
3. Set the from option that determines the result index to start searching from. Defaults to 0.
4. Set the size option that determines the number of search hits to return. Defaults to 10.
5. Set an optional timeout that controls how long the search is allowed to take.

Size 和 From 就是通常所说的偏移/限制。

如果你频繁使用滚动 API，你可能想看看它，因为基于偏移/限制的结果遍历在某些情况下可能会有点慢，而滚动 API 是避免大部分这种情况的方法(如果您来自 SQL 背景，正如我从限制/偏移术语中猜测的那样，将 Scroll API 视为相当于保持 SQL 游标打开以从您停止迭代的位置继续进行)。