Deltalake错误-MERGE目标仅支持Delta源

问题描述

我正在尝试在三角洲湖泊中实施scd-type-2，但出现以下错误-“ MERGE目标仅支持三角洲源”。

下面是我正在执行的代码段。

MERGE INTO stageviews.employeetarget t
            USING (
                  -- The records from the first select statement,will have both new & updated records
                  SELECT id as mergeKey,src.*
                  FROM stageviews.employeeupdate src
                  UNION ALL
                  -- Identify the updated records & setting the mergeKey to NULL forces these rows to NOT MATCH and be INSERTED into target.
                  SELECT NULL as mergeKey,src.*
                  FROM stageviews.employeeupdate src JOIN stageviews.employeetarget tgt
                  ON src.id = tgt.id 
                  WHERE tgt.ind_flag = "1"
                  AND sha2(src.EmployeeName,256) <> sha2(tgt.EmployeeName,256)
                  ) as s
ON t.id = s.mergeKey
WHEN MATCHED AND 
  ( t.ind_flag = "1" AND sha2(t.EmployeeName,256) <> sha2(s.EmployeeName,256) ) THEN  
  UPDATE SET t.ind_flag = "0",t.eff_end_date = current_date()-1
WHEN NOT MATCHED THEN 
  INSERT(t.Id,t.EmployeeName,t.JobTitle,t.BasePay,t.OvertimePay,t.OtherPay,t.Benefits,t.TotalPay,t.TotalPayBenefits,t.Year,t.Notes,t.Agency,t.Status,t.ind_flag,t.create_date,t.update_date,t.eff_start_date,t.eff_end_date)
  values(s.Id,s.EmployeeName,s.JobTitle,s.BasePay,s.OvertimePay,s.OtherPay,s.Benefits,s.TotalPay,s.TotalPayBenefits,s.Year,s.Notes,s.Agency,s.Status,s.ind_flag,current_date(),to_date('9999-12-31'))

解决方法

不幸的是，Databricks仅支持对delta（delta lake）表的更新。

错误消息SQL语句中的错误：AnalysisException：MERGE目标仅支持Delta源，指示您尝试在非增量表上进行更新。

将基于源表的一组更新，插入和删除合并到目标Delta表中。

参考： Azure Databricks - Merge和SCD Type 2 using Merge。