elasticsearch搜索请求没有访问每个shard

Question

该问题是偶现的，大概两次出一次，按照id搜索有几率搜索部分shard
我的搜索请求是这样的
{
"size" : 1,
"timeout" : 10000,
"query" : {
"term" : {
"id" : "e5b5a7d1b8d27a7507c75068584a92db"
}
}
}

下面是搜索部分shard的，可以看到请求只抵达了185个shard
{
    "took" : 125,
    "timed_out" : false,
    "_shards" : {
        "total" : 225,
        "successful" : 185,
        "failed" : 0
    },
    "hits" : {
        "total" : 0,
        "max_score" : null,
        "hits" : [ ]
    }

}

然后正常的搜索结果是这样的
{
"took" : 442,
"timed_out" : false,
"_shards" : {
"total" : 225,
"successful" : 225,
"failed" : 0
},
"hits" : {
"total" : 1,
"max_score" : 12.005859,
"hits" : [ {
"_index" : "xysso-document-201811",
"_type" : "document",
"_id" : "e5b5a7d1b8d27a7507c75068584a92db",
"_score" : 12.005859,
"_source" : {
"id" : "e5b5a7d1b8d27a7507c75068584a92db",
"title" : "溧水一旅游厕所获省级大奖",
"content" : "马上注册，结交更多好友",
}
} ]
}
}
请问是怎么回事？