SSIS Merge Join Clarification

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What is logic behind the merge join in SSIS? In SQL server, we don't have to sort the sources before join. But why it is necessary in SSIS?

Posted 19-Oct-12 7:11am

SiddhuFresher

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Hi,

Sql Server Merge is used to add new value or modify the existing value basing upon the conditions matches or not matches . It improves the performance of the database as it passes through data only once.

SSIS Merge and Merge Join:

Here we need to sort the data before we apply above transformations in the data flow tasks. Merge combines the data in row wise level where merge join combines the data in column wise level. If at all, when we use different oledb sources, excel sources and flat files and when we just want to combine the data as a single table (interms of columns) we go for merge join transformations. Where as when we want to combine the data in a row level.

Please excuse and rectify me if wrongly said.

Thanks,
Durga

Posted 11-Nov-14 2:50am

Durga Venkata Avinash

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fjdiewornncalwe · Accepted Answer · 2012-10-19T08:41:00

From MSDN Documentation: In Integration Services, the Merge and Merge Join transformations require sorted data for their inputs. The input data must be sorted physically, and sort options must be set on the outputs and the output columns in the source or in the upstream transformation. If the sort options indicate that the data is sorted, but the data is not actually sorted, the results of the merge or merge join operation are unpredictable.
When I read something like this my first impression is that I believe there must be a significant performance increase or a significant simplifying of complex logic happening under the hood. Not sure if that helps you, but if you want, I got the info here[^].