Painless scripting — Elastic Stack 实战手册-阿里云开发者社区

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Painless scripting — Elastic Stack 实战手册

简介: Painless scripting 是一种简单的、安全的针对 Elasticsearch 设计的脚本语言,Painless 可以使用在任何可以使用 scripting 的场景

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创作人:李增胜

Painless scripting 是一种简单的、安全的针对 Elasticsearch 设计的脚本语言,Painless 可以使用在任何可以使用 scripting 的场景。脚本提供了以下优点:

  • 更高的性能,scripting 脚本比其他的可选脚本快数倍。
  • 安全性高,更小颗粒度的字段授权机制,避免可能不必要的安全隐患安全。
  • 可选类型,变量和参数可以使用显示或者动态类型编程方式。
  • 语法,扩展 Java 的语法并兼容了其他脚本。
  • 优化,专为 Elasticsearch 设计的脚本语言。

常用关键字:

if、else、while、do、for、in,continue,break,return,
new、try、catch、throw、this、instanceof。

常用举例

首先我们创建测试数据,商品信息

#添加测试数据
POST my_goods/_bulk
{"index":{"_id":1}}
{"goodsName":"苹果 51英寸 4K超高清","skuCode":"skuCode1","brandName":"苹果","closeUserCode":["0"],"channelType":"cloudPlatform","shopCode":"sc00001","publicPrice":8188.88,"groupPrice":null,"boxPrice":null,"boostValue":1.8}
{"index":{"_id":2}}
{"goodsName":"苹果 55英寸 3K超高清","skuCode":"skuCode2","brandName":"苹果","closeUserCode":["0"],"channelType":"cloudPlatform","shopCode":"sc00002","publicPrice":6188.88,"groupPrice":null,"boxPrice":null,"boostValue":1.0}
{"index":{"_id":3}}
{"goodsName":"苹果UA55RU7520JXXZ 53英寸 4K高清","skuCode":"skuCode3","brandName":"美国苹果","closeUserCode":["0"],"channelType":"cloudPlatform","shopCode":"sc00001","publicPrice":8388.88,"groupPrice":null,"boxPrice":[{"boxType":"box1","boxUserCode":["htd003","uc004"],"boxPriceDetail":4388.88},{"boxType":"box2","boxUserCode":["uc005","uc0010"],"boxPriceDetail":5388.88}],"boostValue":1.2}
{"index":{"_id":4}}
{"goodsName":"山东苹果UA55RU7520JXXZ 苹果54英寸 5K超高清","skuCode":"skuCode4","brandName":"山东苹果","closeUserCode":["uc001","uc002","uc003"],"channelType":"cloudPlatform","shopCode":"sc00001","publicPrice":8488.88,"groupPrice":[{"level":"level1","boxLevelPrice":"2488.88"},{"level":"level2","boxLevelPrice":"3488.88"}],"boxPrice":[{"boxType":"box1","boxUserCode":["uc004","uc005","uc006","uc001"],"boxPriceDetail":4488.88},{"boxType":"box2","boxUserCode":["htd007","htd008","htd009","uc0010"],"boxPriceDetail":5488.88}],"boostValue":1.2}

Inline script

少量代码跟随其他 DSL 一起执行的脚本,在下面的例子用会说明具体案例。

添加字段

如果我们想添加一个新字段,而新字段又依赖已有字段,如下所示,我们添加一个新品牌,品牌的名称为原有品牌的基础上拼接“新品”,就可以使用脚本来实现此业务。

POST my_goods/_update_by_query
{
  "script": {
    "source": "ctx._source.new_brandName = ctx._source.brandName + '新品'"
  }
}

#查询结果
GET my_goods/_search

#返回(省略部分无关字段)
"hits" : [
      {
        "_index" : "my_goods",
        "_source" : {
          "shopCode" : "sc00001",
          "new_brandName" : "苹果新品",
          "brandName" : "苹果",
          "closeUserCode" : [
            "0"
          ]
        }
      },
      {
        "_index" : "my_goods",
        "_type" : "_doc",
        "_id" : "2",
        "_score" : 1.0,
        "_source" : {
          "shopCode" : "sc00002",
          "new_brandName" : "苹果新品",
          "brandName" : "苹果",
          "closeUserCode" : [
            "0"
          ],
          "groupPrice" : null,
          "boxPrice" : null,
          "channelType" : "cloudPlatform",
          "boostValue" : 1.0,
          "publicPrice" : "6188.88",
          "goodsName" : "苹果 55英寸 3K超高清",
          "skuCode" : "skuCode2"
        }
      },
     ....
    ]

#可以看到使用脚本新增的字段 new_brandName 已经生效

上面的 source 表示我们使用了 Painless 脚本代码,这种使用少量代码在 DSL 中的 Painless 脚本称为 Inline script 。

删除字段

当我们需要删除已有字段时,可以通过脚本来删除

POST my_goods/_update_by_query
{
  "script": {
    "source": "ctx._source.remove('new_brandName')"
  }
}

更改字段值

在更改字段值时,我们使用了 params 参数的形式进行处理,使用 params 有一定优点,当脚本中 source 值一样时,ES 会视为同一个脚本,会进行缓存不需要重新编译,可以加快处理速度,在下次使用时可以拿出来直接使用而不用经过编译。

#性能较差,硬编码实现价格提升2倍
POST my_goods/_update/1
{
  "script": {
    "source": "ctx._source.publicPrice = ctx._source.publicPrice * 2",
    "lang": "painless"
  }
}

#性能较优,使用 params 将 ID 为1的商品的价格提高2倍
POST my_goods/_update/1
{
  "script": {
    "source": "ctx._source.publicPrice = ctx._source.publicPrice * params.promote_percent",
    "lang": "painless",
    "params": {
      "promote_percent": 2
    }
  }
}

#查询
GET my_goods/_doc/1

#返回
{
  "_index" : "my_goods",
  "_type" : "_doc",
  "_id" : "1",
  "_version" : 2,
  "_seq_no" : 4,
  "_primary_term" : 1,
  "found" : true,
  "_source" : {
    "goodsName" : "苹果 51英寸 4K超高清",
    "skuCode" : "skuCode1",
    "brandName" : "苹果",
    "closeUserCode" : [
      "0"
    ],
    "channelType" : "cloudPlatform",
    "shopCode" : "sc00001",
    "publicPrice" : 16377.76,
    "groupPrice" : null,
    "boxPrice" : null,
    "boostValue" : 1.8
  }
}
#可以看到,在更新前价格为“8188.88”,通过脚本更新后价格变为16377.76

在 Elasticsearch 中,以下的脚本会视为一个脚本:

"source": "ctx._source.publicPrice = ctx._source.publicPrice * params.promote_percent"

下面的会被认为是 2 个不同的脚本,运行时每次都需要编译,性能比上面使用 params

稍差:

"source": "ctx._source.publicPrice = ctx._source.publicPrice * 2"
"source": "ctx._source.publicPrice = ctx._source.publicPrice * 3"

排序

#修改goodsName可以被doc访问
PUT my_goods/_mapping
{
  "properties": {
    "goodsName":{
      "type":"text", 
      "fielddata": "true"
    }
  }
}
#查询并排序,根据商品名称长度并添加干扰因子1.1倍为最终排序结果
POST my_goods/_search
{
  "query": {
    "match": {
      "brandName": "苹果"
    }
  },
  "sort": {
    "_script": {
      "type": "number",
      "script": {
        "lang": "painless",
        "source": "doc['goodsName'].value.length() * params.factor",
        "params": {
          "factor": 1.1
        }
      },
      "order": "asc"
    }
  }
}

Stored script

先将脚本存储,在 DSL 查询时使用已经存储更好的脚本,叫做 stored script

#定义 stored script,脚本名称为:promote_price
PUT _scripts/promote_price
{
  "script": {
    "source": "ctx._source.publicPrice = ctx._source.publicPrice * params.value",
    "lang": "painless"
  }
}

如上代码所示,我们定义了一个名称为 promote_price 的脚本,作用就是提升售卖价格(publicPrice)一定的倍数,这个倍数是在调用时传入的。

POST my_goods/_update_by_query
{
  "script": {
    "id": "promote_price",
    "params": {
      "value": 2
    }
  }
}

执行 stored script,将会看到价格提升了 2 倍

Source 里字段访问

在使用 Painless 访问 Source 里的字段值时,需要根据运行时的上下文来确定使用的语法,Painless 常见的上下文有:update 、update_by_query、sort、ingest pipeline 等。

Context访问字段
updatectx._source.field_name
ingest nodectx.field_name

分别举例使用 _source 与 ctx 来操作字段的值。

update

# 在上面的例子中,就曾使用过ctx._source.field_name 来更新数据
POST my_goods/_update/1
{
  "script": {
    "source": "ctx._source.publicPrice = ctx._source.publicPrice * params.promote_percent",
    "lang": "painless",
    "params": {
      "promote_percent": 2
    }
  }
}

ingest node

在ingest pipeline中更新字段值

#定义 pipeline
PUT _ingest/pipeline/add_my_goods_newField
{
  "processors": [
    {
      "script": {
        "lang": "painless",
        "source": "ctx.skuCode_brandName = ctx.skuCode + ctx.brandName"
      }
    }
  ]
}

#执行 pipeline
POST my_goods/_update_by_query?pipeline=add_my_goods_newField
{
  
}

#查询结果
GET my_goods/_search

#返回
"hits" : [
      {
        "_index" : "my_goods",
        "_type" : "_doc",
        "_id" : "2",
        "_score" : 1.0,
        "_source" : {
          "shopCode" : "sc00002",
          "brandName" : "苹果",
          "closeUserCode" : [
            "0"
          ],
          "skuCode_brandName" : "skuCode2苹果",
          "channelType" : "cloudPlatform",
          "publicPrice" : 12377.76,
          "goodsName_length" : 13,
          "groupPrice" : null,
          "boxPrice" : null,
          "boostValue" : 1.0,
          "goodsName" : "苹果 55英寸 3K超高清",
          "skuCode" : "skuCode2"
        }
      },
      {
        "_index" : "my_goods",
        "_type" : "_doc",
        "_id" : "3",
        "_score" : 1.0,
        "_source" : {
          "shopCode" : "sc00001",
          "brandName" : "美国苹果",
          "closeUserCode" : [
            "0"
          ],
          "skuCode_brandName" : "skuCode3美国苹果",
          "channelType" : "cloudPlatform",
          "publicPrice" : 16777.76,
          "goodsName_length" : 26,
          "groupPrice" : null,
          "boxPrice" : [
            {
              "boxType" : "box1",
              "boxUserCode" : [
                "htd003",
                "uc004"
              ],
              "boxPriceDetail" : 4388.88
            },
            {
              "boxType" : "box2",
              "boxUserCode" : [
                "uc005",
                "uc0010"
              ],
              "boxPriceDetail" : 5388.88
            }
          ],
          "boostValue" : 1.2,
          "goodsName" : "苹果UA55RU7520JXXZ 53英寸 4K高清",
          "skuCode" : "skuCode3"
        }
      },
   ....
]

可以看到 ,skuCode_brandName 是通过 skuCode+brandName 拼接成功的,通过 ctx.field 访问字段成功。

Painless Debug

Elasticsearch 中为我们提供了脚本调试方法,使我们在使用时可以方便的进行脚本调试,

#定义用户信息,shop_id为用户开的店铺ID信息
PUT /user_info/_doc/1?refresh
{
  "first": "Michael",
  "last": "Jordan",
  "shop_id": [
    100,
    102,
    103
  ],
  "time": "2021-05-09"
}

PUT /user_info/_doc/2?refresh
{
  "first": "Michael2",
  "last": "Jordan2",
  "shop_id": [
    110,
    112,
    113,
    114,
    115
  ],
  "time": "2021-05-08"
}


#查看mapping
GET  user_info/_mapping

#返回

{
  "user_info" : {
    "mappings" : {
      "properties" : {
        "first" : {
          "type" : "text",
          "fields" : {
            "keyword" : {
              "type" : "keyword",
              "ignore_above" : 256
            }
          }
        },
        "last" : {
          "type" : "text",
          "fields" : {
            "keyword" : {
              "type" : "keyword",
              "ignore_above" : 256
            }
          }
        },
        "shop_id" : {
          "type" : "long"
        },
        "time" : {
          "type" : "date"
        }
      }
    }
  }
}

可以看到返回了很多字段类型,包括:long、date、keyword、text,每种类型有哪些方法可以操作呢?一种是查看官网文档,另外一种获取使用的方法就是通过调试来获取信息了,使用_explain 来看看效果:

POST /user_info/_explain/1
{
  "query": {
    "script": {
      "script": "Debug.explain(doc.shop_id)"
    }
  }
}

#返回:
{
  "error": {
    "root_cause": [
      {
        "type": "script_exception",
        "reason": "runtime error",
        "painless_class": "org.elasticsearch.index.fielddata.ScriptDocValues.Longs",
        "to_string": "[100, 102, 103]",
        "java_class": "org.elasticsearch.index.fielddata.ScriptDocValues$Longs",
        "script_stack": [
          "Debug.explain(doc.shop_id)",
          "                 ^---- HERE"
        ],
        "script": "Debug.explain(doc.shop_id)",
        "lang": "painless",
        "position": {
          "offset": 17,
          "start": 0,
          "end": 26
        }
      }
    ],
    "type": "script_exception",
    "reason": "runtime error",
    "painless_class": "org.elasticsearch.index.fielddata.ScriptDocValues.Longs",
    "to_string": "[100, 102, 103]",
    "java_class": "org.elasticsearch.index.fielddata.ScriptDocValues$Longs",
    "script_stack": [
      "Debug.explain(doc.shop_id)",
      "                 ^---- HERE"
    ],
    "script": "Debug.explain(doc.shop_id)",
    "lang": "painless",
    "position": {
      "offset": 17,
      "start": 0,
      "end": 26
    },
    "caused_by": {
      "type": "painless_explain_error",
      "reason": null
    }
  },
  "status": 400
}

可以看到是一个 runtime error 异常,那我们应该如何解决呢?

仔细观察,doc.shop_id 是这样的类提供支撑:

"painless_class": "org.elasticsearch.index.fielddata.ScriptDocValues.Longs"
"java_class": "org.elasticsearch.index.fielddata.ScriptDocValues$Longs"

通过 Painless Script 的 API 帮助:https://www.elastic.co/guide/en/elasticsearch/painless/7.10/painless-api-reference.html

最终找到 Long 类型的 API 文档地址:https://www.elastic.co/guide/en/elasticsearch/painless/7.10/painless-api-reference-shared-org-elasticsearch-index-fielddata.html#painless-api-reference-shared-ScriptDocValues-Longs

ScriptDocValues.Longs

  • List asList()
  • int getLength()
  • Collection asCollection()
  • Long get(int)
  • .......

我们通过观察数据知道 shop_id 存储的是一个 list 数据,加入我们要获取第一个数据,

再次调整脚本:

GET user_info/_search
{
  "query": {
    "function_score": {
      "script_score": {
        "script": {
          "lang": "painless",
          "source": """
               return doc['shop_id'].getLength();
          """
        }
      }
    }
  }
}

#返回:

{
  "took" : 1,
  "timed_out" : false,
  "_shards" : {
    "total" : 1,
    "successful" : 1,
    "skipped" : 0,
    "failed" : 0
  },
  "hits" : {
    "total" : {
      "value" : 2,
      "relation" : "eq"
    },
    "max_score" : 5.0,
    "hits" : [
      {
        "_index" : "user_info",
        "_type" : "_doc",
        "_id" : "2",
        "_score" : 5.0,
        "_source" : {
          "first" : "Michael2",
          "last" : "Jordan2",
          "shop_id" : [
            110,
            112,
            113,
            114,
            115
          ],
          "time" : "2021-05-08"
        }
      },
      {
        "_index" : "user_info",
        "_type" : "_doc",
        "_id" : "1",
        "_score" : 3.0,
        "_source" : {
          "first" : "Michael",
          "last" : "Jordan",
          "shop_id" : [
            100,
            102,
            103
          ],
          "time" : "2021-05-09"
        }
      }
    ]
  }
}

可以看到,得分最高的为 "max_score" : 5.0, 因为我们使用 script_score 调整了评分,以店铺 ID 个数为评分结果,文档 2 共计 5 个ID,所以返回的是 5 。

通过以上案例,详细解读了 Painless Debug 在实际场景中的应用,通过一步步分析最终掌握了调试、看错误信息、找官方文档解决的方法,最终实现了掌握 Painless Debug 的目的。

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