作用:

      1.释放已删除但未释放磁盘的数据

      2.提高查询速度

API

参数详解

POST /my-index-000001/_forcemerge 
http://localhost:9200/my-index-000001/_forcemerge ?max_num_segments =1&only_expunge_deletes=false&wait_for_merge=false&flush=false

JAVA方式:

    @Resource
    ElasticsearchTemplate elasticsearchTemplate

    private void merge(String... indexName) {
        IndicesAdminClient indices = elasticsearchTemplate.getClient().admin().indices();
        logger.info("ES索引开始优化，索引名为:" + indexName);
        ForceMergeRequestBuilder forceMergeRequestBuilder = indices.prepareForceMerge(indexName)
                .setOnlyExpungeDeletes(false)
                .setMaxNumSegments(1);
        ActionFuture<ForceMergeResponse> responseActionFuture = indices.forceMerge(forceMergeRequestBuilder.request());
        logger.info("ES索引优化成功");
    }

参考:Elasticsearch 高级优化