如何在Druid转换规范表达式中检查“in”子句

Question

我正在查找检查Druid转换表达式中的“in”子句。

我想检查并派生一个满足以下条件的字段：

severity_analysis_period IN ('Critical') 
  THEN '>4hr Deviation' ,
when severity_analysis_period IN ('High', 'Medium', 'Low') 
  THEN '<4hr Deviation' else 'No Deviation'.

我像这样编写了转换规范，但它不起作用：

    "transformSpec": {
      "transforms": [
        {
          "type": "expression",
          "name": "deviation",
          "expression": "if(\"severity_analysis_period\"='Critical'),'>4hr Deviation',if(\"severity_analysis_period\" in ('High','Medium','Low'),'<4hr Deviation','No Deviation'))"
        },
        {
          "type": "expression",
          "name": "deviation_day",
          "expression": "if((\"severity_day\"='Critical'),'>4hr Deviation',if(\"severity_day in\" ('High','Medium','Low'),'<4hr Deviation','No Deviation'))"
        },
        {
          "type": "expression",
          "name": "deviation_hour",
          "expression": "if((\"severity_day_hour\"='Critical'),'>4hr Deviation',if(\"severity_day_hour\" in ('High','Medium','Low'),'<4hr Deviation','No Deviation'))"
        }
      ],
    }

Answer 1

您可以尝试使用case语句：

{
      "type": "expression",
      "name": "deviation_hour",
      "expression": 'case_simple("severity_analysis_period", "Critical", ">4hr Deviation", "High", "<4hr Deviation", "Medium", "<4hr Deviation", "Low", "<4hr Deviation", "No Deviation")'
}

case_simple函数的工作方式如下：

case_simple(expr, value1, result1, [[value2, result2, ...], else-result])

另请参阅：https://druid.apache.org/docs/latest/misc/math-expr.html