Elasticsearch如何开启translog异步写入以提高写入速度

结合数据写入情况，通过下面方式设置translog async落盘：

PUT my_index

{

 "settings": {

      "index": {

           "refresh_interval": "60s",

           "translog": {

                "flush_threshold_size": "2gb",

                "sync_interval": "100s",

                "durability": "async"

           },

           "merge": {

                "policy": {

                     "segments_per_tier": "30",

                     "max_merged_segment": "256m"

                }

           }

      }

 }

}