解决——》The difference between max_gram and min_gram in NGram Tokenizer must be less than or equal to

待我称王封你为后i 2024-03-22 14:47 34阅读 0赞

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> [总结——》【Redis】][Redis]  
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> [总结——》【Elasticsearch】][Elasticsearch]

#### Elasticsearch——》解决：The difference between max\_gram and min\_gram in NGram Tokenizer must be less than or equal to : \[1\] but was \[2\] ####

*  1、操作
 *  2、现象
 *  3、原因
 *  4、解决
 *   *  情况1：设置所有索引的index.max\_ngram\_diff
     *  情况2：创建映射时，设置index.max\_ngram\_diff
     *  情况3：索引创建后，设置max\_ngram\_diff参数
 *  5、注意

## 1、操作 ##

创建映射时，指定ngram分词器

DELETE my_index
    PUT my_index
    {
        
      "settings": {
        
        "analysis": {
        
          "analyzer": {
        
            "my_analyzer": {
        
              "tokenizer": "my_tokenizer"
            }
          },
          "tokenizer": {
        
            "my_tokenizer": {
        
              "type": "ngram",
              "min_gram": 2,
              "max_gram": 4
            }
          }
        }
      }
    }

## 2、现象 ##

{
        
      "error": {
        
        "root_cause": [
          {
        
            "type": "illegal_argument_exception",
            "reason": "The difference between max_gram and min_gram in NGram Tokenizer must be less than or equal to: [1] but was [2]. This limit can be set by changing the [index.max_ngram_diff] index level setting."
          }
        ],
        "type": "illegal_argument_exception",
        "reason": "The difference between max_gram and min_gram in NGram Tokenizer must be less than or equal to: [1] but was [2]. This limit can be set by changing the [index.max_ngram_diff] index level setting."
      },
      "status": 400
    }

![image.png][]

## 3、原因 ##

Elasticsearch 默认情况下设置了一个名为 `index.max_ngram_diff` 的参数，用于限制 `max_gram` 与 `min_gram` 之间的最大差距。  
默认max\_gram 和 min\_gram 参数的差异必须小于或等于 \[1\]，但当前这个差异值为 \[2\]，超出了 Elasticsearch 允许的最大差距，导致无法创建索引。

## 4、解决 ##

通过更改 `index.max_ngram_diff` 参数的值来允许更大的 max\_gram 和 min\_gram 差异值。

### 情况1：设置所有索引的index.max\_ngram\_diff ###

1.  修改 `elasticsearch.yml` 文件中的 index.max\_ngram\_diff 参数的值
2.  重新启动 Elasticsearch 进程

# 设置所有索引的 index.max_ngram_diff 参数值为 10
    index.max_ngram_diff: 10

### 情况2：创建映射时，设置index.max\_ngram\_diff ###

> 我对应的是情况2，所以我使用了这个方式来解决

# 创建映射时，设置index.max_ngram_diff
    PUT /my_index
    {
        
      "settings": {
        
        "index": {
        
          "max_ngram_diff": 10
        },
        
        "analysis": {
        
          "analyzer": {
        
            "my_analyzer": {
        
              "tokenizer": "my_tokenizer"
            }
          },
          "tokenizer": {
        
            "my_tokenizer": {
        
              "type": "ngram",
              "min_gram": 2,
              "max_gram": 4
            }
          }
        }
      },
      "mappings": {
        
        // 映射定义
      }
    }

### 情况3：索引创建后，设置max\_ngram\_diff参数 ###

# 索引创建后，设置max_ngram_diff参数
    PUT /my_index/_settings
    {
        
        "index": {
        
            "max_ngram_diff": 10
        }
    }

## 5、注意 ##

如果将 index.max\_ngram\_diff 参数设置得太大，会产生大量的 n-gram，导致索引大小增加并影响性能。因此，需要根据具体情况选择一个合适的值。

[Java]: https://blog.csdn.net/weixin_43453386/article/details/84788317
[Mysql]: https://blog.csdn.net/weixin_43453386/article/details/88667709
[Redis]: https://blog.csdn.net/weixin_43453386/article/details/127966762
[Kafka]: https://blog.csdn.net/weixin_43453386/article/details/128189472
[Spring]: https://blog.csdn.net/weixin_43453386/article/details/124900806
[SpringBoot]: https://blog.csdn.net/weixin_43453386/article/details/84788714
[MyBatis_MyBatis-Plus]: https://blog.csdn.net/weixin_43453386/article/details/84788053
[Linux]: https://blog.csdn.net/weixin_43453386/article/details/89241912
[MongoDB]: https://blog.csdn.net/weixin_43453386/article/details/84788450
[Elasticsearch]: https://blog.csdn.net/weixin_43453386/article/details/108583782
[image.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/18/6dde64cee19d4b7e93d8cbb1d702700f.png