概念
Scripting是Elasticsearch支持的一种专门用于复杂场景下支持自定义编程的强大的脚本功能，ES支持多种脚本语言，如painless，其语法类似于Java,也有注释、关键字、类型、变量、函数等，其就要相对于其他脚本高出几倍的性能，并且安全可靠，可以用于内联和存储脚本。
支持的语言
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groovy：ES 1.4.x-5.0的默认脚本语言
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painless：JavaEE使用java语言开发，.Net使用C#/F#语言开发，Flutter使用Dart语言开发，同样，ES 5.0+版本后的Scripting使用的语言默认就是painless，painless是一种专门用于Elasticsearch的简单,用于内联和存储脚本，是ES 5.0+的默认脚本语言，类似于Java,也有注释、关键字、类型、变量、函数等，是一种安全的脚本语言。并且是Elasticsearch的默认脚本语言。
-
其他：
expression：每个文档的开销较低：表达式的作用更多，可以非常快速地执行，甚至比编写native脚本还要快，支持javascript语法的子集：单个表达式。缺点：只能访问数字，布尔值，日期和geo_point字段，存储的字段不可用
mustache：提供模板参数化查询
特点
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语法简单，学习成本低
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灵活度高，可编程能力强
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性能相较于其他脚本语言很高
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安全性好
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独立语言，虽然易学但仍需单独学习
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相较于DSL性能低
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不适用于复杂的业务场景
应用场景
各种复杂的应用场景，如自定义评分、自定义聚合查询等。
正则:
早先某些版本正则表达式默认情况下处于禁用模式，因为它绕过了painless的针对长时间运行和占用内存脚本的保护机制。而且有深度对战行为。如果需要开启正则，需要配置：script.painless.regex.enabled: true
注意：通常正则的使用范围比较小，应用范围基本限制在数据量比较小和并发量比较小的应用场景下。
doc['field'].value和params['_source']['field']：
理解之间的区别是很重要的，doc['field'].value和params['_source']['field']。首先，使用doc关键字，将导致该字段的条件被加载到内存（缓存），这将导致更快的执行，但更多的内存消耗。此外，doc[...]符号只允许简单类型（不能返回一个复杂类型(JSON对象或者nested类型)），只有在非分析或单个词条的基础上有意义。但是，doc如果可能，使用仍然是从文档访问值的推荐方式，因为_source每次使用时都必须加载并解析。使用_source非常缓慢###
代码示例
POST product/_update/2
{"script": {"source": "ctx._source.price-=1"}
}
POST product/_update/2
{"script": {"source": "ctx._source.price-=ctx._version"}
}
#简写
POST product/_update/2
{"script": "ctx._source.price-=1"
}
# Scripting的CRUD
POST _reindex
{"source": {"index": "product"},"dest": {"index": "product2"}
}
# 举个例子：华为出了新款 新增了tag 叫做“遥遥领先”
POST product/_update/6
{"script": {"lang": "painless","source": "ctx._source.tags.add('遥遥领先')"}
}
#upsert update + insert
POST product/_update/3
{"script": {"lang": "painless","source": "ctx._source.price += 100"},"upsert": {"name" : "huaweimate60","desc" : "yyds","price" : 1999}
}
#GET查询 painless expression 应用于促销打折计算
GET product/_search
{"script_fields": {"my_price": {"script": {"lang": "expression","source": "doc['price'].value* 0.9"}}}
}
GET product/_search
{"script_fields": {"my_price": {"script": {"lang": "painless","source": "doc['price'].value* 0.9"}}}
}
#参数化
POST product/_update/2
{"script": {"lang": "painless","source": "ctx._source.tags.add(params.tag_name)","params": {"tag_name":"无线秒充"}}
}
GET product/_search
{"script_fields": {"my_price": {"script": {"lang": "painless","source": "doc['price'].value* params.num","params": {"num": 9 }}}}
}
#多个折扣
GET product/_search
{"script_fields": {"price": {"script": {"lang": "painless","source": "doc['price'].value"}},"discount_price": {"script": {"lang": "painless","source": "[doc['price'].value* params.discount_8,doc['price'].value* params.discount_7,doc['price'].value* params.discount_6,doc['price'].value* params.discount_5]","params": {"discount_8": 0.8,"discount_7": 0.7,"discount_6": 0.6,"discount_5": 0.5}}}}
}
# Stored scripts scripts模板
# /_scripts/{id}
POST _scripts/calculate_discount
{"script": {"lang": "painless","source": "doc.price.value * params.discount"}
}
#查看
GET _scripts/calculate_discount
GET product/_search
{"script_fields": {"price": {"script": {"lang": "painless","source": "doc['price'].value"}},"discount_fields": {"script": {"id": "calculate_discount","params": {"discount":0.8}}}}
}
#Scripting的函数式编程
GET product/_search
GET product/_doc/1
POST product/_update/1
{"script": {"lang": "painless","source": "ctx._source.tags.add(params.tag_name)","params": {"tag_name":"无线秒充"}}
}
POST product/_update/1
{"script": {"lang": "painless","source": """ctx._source.tags.add(params.tag_name);ctx._source.price-=100;""","params": {"tag_name":"无线秒充1"}}
}
#正则like %小米% /[\s\S]*小米[\s\S]*/
POST product/_update/3
{"script": {"lang": "painless","source": """if(ctx._source.name ==~ /[\s\S]*小米[\s\S]*/) {ctx._source.name+="***|"}else{ctx.op="noop"}"""}
}
#/\d{4}-\d{2}-\d{2}[\s\S]*/
GET product/_doc/1
POST product/_update/1
{"script": {"lang": "painless","source": """if(ctx._source.createtime ==~ /\d{4}-\d{2}-\d{2}[\s\S]*/) {ctx._source.name+="|***"}else{ctx.op="noop"}"""}
}
#统计所有价格小于1000的商品的tag的数量 不考虑重复的情况
GET product/_search
{"query": {"constant_score": {"filter": {"range": {"price": {"lte": 1000}}}}},"aggs": {"tag_agg": {"sum": {"script": {"lang": "painless","source": """int total = 0;for(int i = 0; i <doc['tags.keyword'].length; i++){total++;}return total;"""}}}}
}
# 对于一些早期版本 script.painless.regex.enabled: true
# doc['field'].value 和 params['_source']['field']
#批量新增
PUT test_index/_bulk?refresh
{"index":{"_id":1}}
{"ajbh": "12345","ajmc": "立案案件","lasj": "2020/05/21 13:25:23","jsbax_sjjh2_xz_ryjbxx_cleaning": [{"XM": "张三","NL": "30","SF": "男"},{"XM": "李四","NL": "31","SF": "男"},{"XM": "王五","NL": "30","SF": "女"},{"XM": "赵六","NL": 23,"SF": "男"}]}
{"index":{"_id":2}}
{"ajbh": "563245","ajmc": "结案案件","lasj": "2020/05/21 13:25:23","jsbax_sjjh2_xz_ryjbxx_cleaning": [{"XM": "张三2","NL": "30","SF": "男"},{"XM": "李四2","NL": "31","SF": "男"},{"XM": "王五2","NL": "30","SF": "女"},{"XM": "赵六2","NL": "23","SF": "女"}]}
{"index":{"_id":3}}
{"ajbh": "12345","ajmc": "立案案件","lasj": "2020/05/21 13:25:23","jsbax_sjjh2_xz_ryjbxx_cleaning": [{"XM": "张三3","NL": "30","SF": "男"},{"XM": "李四3","NL": "31","SF": "男"},{"XM": "王五3","NL": "30","SF": "女"},{"XM": "赵六3","NL": "23","SF": "男"}]}
#统计男性嫌疑人的数量
GET test_index/_search
GET product/_search
#Object Nested
GET /test_index/_search
{"aggs": {"sum_person": {"sum": {"script": {"lang": "painless","source": """int total = 0;for(int i = 0;i< params['_source']['jsbax_sjjh2_xz_ryjbxx_cleaning'].length;i++){if(params['_source']['jsbax_sjjh2_xz_ryjbxx_cleaning'][i]['SF']=='男'){total+=1;}}return total;"""}}}}
}
)
