elasticsearch - 设置 index.max_terms_count 没有效果？

Question

我正在试验 index.max_terms_count。我尝试执行一个包含超过 65 536 个术语的术语查询，我很惊讶地看到它实际上被执行了，因为我读到了警告 here :

Executing a Terms Query request with a lot of terms can be quite slow, as each additional term demands extra processing and memory. To safeguard against this, the maximum number of terms that can be used in a Terms Query both directly or through lookup has been limited to 65536 . This default maximum can be changed for a particular index with the index setting index.max_terms_count .

为了进一步测试它，我尝试将 index.max_terms_count 设置为 2 或 3，但它仍然无法按我预期的方式工作。你能帮我理解我在做什么(或理解)错了吗？

步骤:

1. 使用 Docker 运行 ES:

   1.1.docker pull docker.elastic.co/elasticsearch/elasticsearch:6.6.0

   1.2。 docker run -p 9200:9200 -p 9300:9300 -e "discovery.type=single-node"docker.elastic.co/elasticsearch/elasticsearch:6.6.0

2. 索引文档:curl -X POST http://localhost:9200/twitter/_doc/1 -H '内容类型:应用程序/json' -d '{ “用户”:“泡菜”， “发布日期”:“2009-11-15T14:12:12”， "message": "试用 Elasticsearch", “标签”:[“富”，“酒吧”，“太阳”，“云”]}'

3. 更改设置:curl -X PUT http://localhost:9200/twitter/_settings -H '内容类型:应用程序/json' -d '{ “指数” : { “max_terms_count”:2 }}'

4. 验证设置是否已应用:curl -X GET http://localhost:9200/twitter/_settings

5. 执行搜索:curl -X POST ' http://localhost:9200/twitter/_search?pretty ' -H '内容类型:application/json' -d '{ “询问”: { “条款”:{“标签”:[“太阳”，“多云”，“哟”，“嗨”，“你好”]} }}'

Answer 1

在 ElasticSearch 版本 7.0 之后，index.max_terms_count 的默认值为 65536，如果您使用默认 向 terms 命令提供超过 65536 的额外输入max_terms_count 设置。例如，65537，它将产生以下异常消息

{
  "error" : {
    "root_cause" : [
      {
        "type" : "query_shard_exception",
        "reason" : "failed to create query: The number of terms [65537] used in the Terms Query request has exceeded the allowed maximum of [65536]. This maximum can be set by changing the [index.max_terms_count] index level setting.",
        "index" : "my_index",
        "index_uuid" : "iJMNOR7znSsmODsG4uArTvQ"
      },
      ....
    ....
    ...
}

Elastic search 提供了一种将 max_terms_count 增加到 2147483647 的方法。出于测试目的，我尝试设置到 2147483647，并且效果很好

PUT /my-index/_settings
{
    "index" : {
        "max_terms_count" :  2147483647  
     }
}

但是当我开始将值增加到 2147483648

时失败了

PUT /my-index/_settings
{
    "index" : {
        "max_terms_count" :  2147483648  
     }
}



{
  "error" : {
    "root_cause" : [
      {
        "type" : "illegal_argument_exception",
        "reason" : "Failed to parse value [2147483648] for setting [index.max_terms_count]"
      }
    ],
    "type" : "illegal_argument_exception",
    "reason" : "Failed to parse value [2147483648] for setting [index.max_terms_count]",
    "caused_by" : {
      "type" : "number_format_exception",
      "reason" : "For input string: \"2147483648\""
    }
  },
  "status" : 400
}

因此，max_terms_count 确实在查询期间发挥作用，并且您的 index.max_terms_count 根据您的配置(有或没有默认)产生影响