C# SSIS ScriptTask SQLBulkCopy Oracle Clob-多个列到单个本地列

我们有一组表，通过将Clob分解为4k块，可以快速从Oracle获取数据。我怀疑一个定制的iDataReader有点像这样：

这是必要的。我正在努力从datareader中获取clob部分，并将它们连接到本地varchar（max）字段中，同时正常处理其他列。我有一个分支路径，因为不是所有表都有这样的字段，并且可以通过另一个路径快速处理

我们已经尝试了很多方法，包括尝试直接将其拉入，切碎后加入oracle，等等。这似乎是获取数据的最快的方法。
（至少一个数量级）

clob列如下所示：

NVL(CAST(substr(DESCRLONG, 1, 4000) as VARCHAR2(4000)), ' ') AS CLOBPART1,  
NVL(CAST(substr(DESCRLONG, 4001, 4000) as VARCHAR2(4000)), ' ') AS CLOBPART2,  
NVL(CAST(substr(DESCRLONG, 8001, 4000) as VARCHAR2(4000)), ' ') AS CLOBPART3,  
NVL(CAST(substr(DESCRLONG, 12001, 4000) as VARCHAR2(4000)), ' ') AS CLOBPART4,  
NVL(CAST(substr(DESCRLONG, 16001, 4000) as VARCHAR2(4000)), ' ') AS CLOBPART5,  
NVL(CAST(substr(DESCRLONG, 20001, 4000) as VARCHAR2(4000)), ' ') AS CLOBPART6,  
NVL(CAST(substr(DESCRLONG, 24001, 4000) as VARCHAR2(4000)), ' ') AS CLOBPART7,  
NVL(CAST(substr(DESCRLONG, 28001, 4000) as VARCHAR2(4000)), ' ') AS CLOBPART8  

本例中的本地字段是DESCRLONG，但可能不同，但clobpart是公共的，并被推送到varchar（max）。显示的非CLOB通路似乎工作良好，其基于顺序位置。显然，对于多对一来说，这不太管用

NVL(CAST(substr(DESCRLONG, 1, 4000) as VARCHAR2(4000)), ' ') AS CLOBPART1,  
NVL(CAST(substr(DESCRLONG, 4001, 4000) as VARCHAR2(4000)), ' ') AS CLOBPART2,  
NVL(CAST(substr(DESCRLONG, 8001, 4000) as VARCHAR2(4000)), ' ') AS CLOBPART3,  
NVL(CAST(substr(DESCRLONG, 12001, 4000) as VARCHAR2(4000)), ' ') AS CLOBPART4,  
NVL(CAST(substr(DESCRLONG, 16001, 4000) as VARCHAR2(4000)), ' ') AS CLOBPART5,  
NVL(CAST(substr(DESCRLONG, 20001, 4000) as VARCHAR2(4000)), ' ') AS CLOBPART6,  
NVL(CAST(substr(DESCRLONG, 24001, 4000) as VARCHAR2(4000)), ' ') AS CLOBPART7,  
NVL(CAST(substr(DESCRLONG, 28001, 4000) as VARCHAR2(4000)), ' ') AS CLOBPART8