1. cardinality计数：

虽然快，但计数不准，原因自行百度

2.自定义脚本计数：

        SearchSourceBuilder sourceBuilder = new SearchSourceBuilder();
        sourceBuilder.from(esPageRange.getFrom());
        sourceBuilder.size(esPageRange.getSize());
        sourceBuilder.collapse(new CollapseBuilder(collapseField));
        sourceBuilder.aggregation(this.scriptedMetricAggregation("termsCount", collapseField));
        sourceBuilder.query(queryBuilder);
        SearchRequest searchRequest = new SearchRequest();
        searchRequest.indices(indexArray);
        searchRequest.source(sourceBuilder);
        //索引不存在时，不报错
        searchRequest.indicesOptions(IndicesOptions.LENIENT_EXPAND_OPEN);
        List<T> resultList = new ArrayList<>();
        long total = 0L;
        SearchResponse response = restHighLevelClient.search(searchRequest, RequestOptions.DEFAULT);
        if (response.getHits().getHits() != null) {
            for (SearchHit hit : response.getHits().getHits()) {
                resultList.add(transHitFunction.apply(hit));
            }
        }
        if (response.getAggregations() != null){
            Aggregations aggregations = response.getAggregations();
            ParsedScriptedMetric scriptedMetric = aggregations.get("termsCount");
            if (scriptedMetric != null && scriptedMetric.aggregation() != null){
                Integer value = (Integer)scriptedMetric.aggregation();
                total = value.longValue();
            }
        }

3.脚本聚合代码：

    public ScriptedMetricAggregationBuilder scriptedMetricAggregation(String aggregationName, String fieldName){
        String initScript = "state.numas=new HashSet();";
        String mapScript = "def array = doc['"+fieldName+"'];\n" +
                "        if(array.length>=1){\n" +
                "            for (def id : array) {\n" +
                "                state.numas.add(id);\n" +
                "            }\n" +
                "        }";
        String combineScript = "return state.numas";
        String reduceScript = "def set =new HashSet();\n" +
                "               for(e in states){\n" +
                "                if(!Objects.isNull(e)){\n" +
                "                    for(key in e){\n" +
                "                set.add(key);\n" +
                "              }\n" +
                "                }\n" +
                "              }\n" +
                "              return set.size();";
        ScriptedMetricAggregationBuilder scriptedMetricAggregationBuilder = AggregationBuilders.scriptedMetric(aggregationName);
        scriptedMetricAggregationBuilder.initScript(new Script(ScriptType.INLINE, PAINLESS, initScript, Collections.emptyMap()));
        scriptedMetricAggregationBuilder.mapScript(new Script(ScriptType.INLINE, PAINLESS, mapScript, Collections.emptyMap()));
        scriptedMetricAggregationBuilder.combineScript(new Script(ScriptType.INLINE, PAINLESS, combineScript, Collections.emptyMap()));
        scriptedMetricAggregationBuilder.reduceScript(new Script(ScriptType.INLINE, PAINLESS, reduceScript, Collections.emptyMap()));
        return scriptedMetricAggregationBuilder;

    }