Getting all records from Elasticsearch using Java API

Question

I am trying to get all the records from Elasticsearch using Java API. But I receive the below error

n[[Wild Thing][localhost:9300][indices:data/read/search[phase/dfs]]]; nested: QueryPhaseExecutionException[Result window is too large, from + size must be less than or equal to: [10000] but was [10101].

My code is as below

Client client;
try {
    client = TransportClient.builder().build().
            addTransportAddress(new InetSocketTransportAddress(InetAddress.getByName("localhost"), 9300));
    int from = 1;
    int to = 100;
    while (from <= 131881) {
        SearchResponse response = client
                .prepareSearch("demo_risk_data")
                .setSearchType(SearchType.DFS_QUERY_THEN_FETCH).setFrom(from)
                .setQuery(QueryBuilders.boolQuery().mustNot(QueryBuilders.termQuery("user_agent", "")))
                .setSize(to).setExplain(true).execute().actionGet();
        if (response.getHits().getHits().length > 0) {
            for (SearchHit searchData : response.getHits().getHits()) {
                JSONObject value = new JSONObject(searchData.getSource());
                System.out.println(value.toString());
            }
        }
    }
}

Total number of records currently present are 131881 ,so I start with from = 1 and to = 100 and then get 100 records until from <= 131881. Is there are way where I can check get records in set of say 100 until there are no further records in Elasticsearch.

Answer 1

Yes, you can do so using the scroll API, which the Java client also supports.

You can do it like this:

Client client;
try {
    client = TransportClient.builder().build().
            addTransportAddress(new InetSocketTransportAddress(InetAddress.getByName("localhost"), 9300));

    QueryBuilder qb = QueryBuilders.boolQuery().mustNot(QueryBuilders.termQuery("user_agent", ""));
    SearchResponse scrollResp = client.prepareSearch("demo_risk_data")
        .addSort(SortParseElement.DOC_FIELD_NAME, SortOrder.ASC)
        .setScroll(new TimeValue(60000))
        .setQuery(qb)
        .setSize(100).execute().actionGet();

    //Scroll until no hits are returned
    while (true) {
        //Break condition: No hits are returned
        if (scrollResp.getHits().getHits().length == 0) {
            break;
        }

        // otherwise read results
        for (SearchHit hit : scrollResp.getHits().getHits()) {
            JSONObject value = new JSONObject(searchData.getSource());
            System.out.println(value.toString());
        }

        // prepare next query
        scrollResp = client.prepareSearchScroll(scrollResp.getScrollId()).setScroll(new TimeValue(60000)).execute().actionGet();
    }
}