mergejoin和lookup之间的区别？哪个更好？为什么不加入合并？ [英] Difference between mergejoin and lookup? which is better? why not merge join?

问题描述

嗨朋友们，

有人可以告诉ans以上吗？



提前感谢

Hi friends,
Can anyone tell the ans for the above??

thanks in advance

推荐答案

查看此链接



SSIS中的合并连接和查找转换之间有什么区别？[ ^ ] />


问候..

See this link

What are the differences between Merge Join and Lookup transformations in SSIS?[^]

Regards..

嗨


如果你想加入2个源表关系的基础，无论它们的位置如何，你都可以使用合并连接，你可以像在T-SQL中那样在这个源表上执行内部，外部连接。



看看Up用于在目标表中查找与源列值相关的值（查找值），即检查源列值与目标列值的对应关系。



以上解决方案还为您提供了更多细节差异。



如果您需要更多信息，请告诉我们细节。



问候

Mubin

Hi
When you want to join 2 source tables on the bases of relation irrespective of their location you can use merge join, you can perform inner, outer join on this source tables as we do in T-SQL.

Look Up is used to find value(look for a value) in destination table with respect to source column values, i.e. check existence of source column value against destination column values.

Above solution also gives you more detail on the differences.

Let us know if you need more detail.

Regards
Mubin

合并加入需要对两个输入进行排序，排序是非常昂贵的操作，因为它是完全阻塞转换，如果你正在加载数百万条记录，那么在包中使用是不可取的。



查找转换是非阻塞转换和排序是不需要。因此，从性能角度来看，查找转换优于合并连接。

Merge Join needs both inputs to be sorted, Sorting is highly expensive operation because it is Fully Blocking transformation which is not suggestible to use in package if you are loading millions of records.

Lookup transformation is non blocking transformation and sorting is not required. So, Lookup transformation is better than Merge Join by performance perspective.

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