How can you recognize these three component types, what is their inner working and do they acquire new buffers and/or threads?
Synchronous vs Asynchronous
The SSIS dataflow contain three types of transformations. They can be non-blocking, semi-blocking or fully-blocking. Before I explain how you can recognize these types and what their properties are its important to know that all the dataflow components can be categorized to be either synchronous or asynchronous.
· Synchronous components
The output of an synchronous component uses the same buffer as the input. Reusing of the input buffer is possible because the output of an synchronous component always contain exactly the same number of records as the input. Number of records IN == Number of records OUT.
· Asynchronous components
The output of an asynchronous component uses a new buffer. It’s not possible to reuse the input buffer because an asynchronous component can have more or less output records then input records.
The only thing you need to remember is that synchronous components reuse buffers and therefore are generally faster than asynchronous components, that need a new buffer.
All source adapters are asynchronous, they create two buffers; one for the success output and one for the error output. All destination adapters on the other hand, are synchronous.
Non-blocking, Semi-blocking and Fully-blocking
In the table below the differences between the three transformation types are summarized. As you can see it’s not that hard to identify the three types.
On the internet are a lot of large and complicated articles about this subject, but I think it’s enough to look at the core differences between the three types to understand their working and (did)advantages:
|
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Non-blocking
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Semi-blocking
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Fully-blocking
|
|
Synchronous or asynchronous
|
Synchronous
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Asynchronous
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Asynchronous
|
|
Number of rows in == number of rows out
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True
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Usually False
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Usually False
|
|
Must read all input before they can output
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False
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False
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True
|
|
New buffer created?
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False
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True
|
True
|
|
New thread created?
|
False
|
Usually True
|
True
|
All SSIS transformations categorized:
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Jorg Klein's Blog 
Good article, very clear!
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Usefull article, thanks a lot !
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Thanks, I have been in wrong notion about some of the transformations. But you cleared it thanks.
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I am trying to build a Destinatino adapter whose error output can be something apart from integer(errocode and index). How can we proceed with that?
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Very good article and very clear.
Thanks a lot.
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Awesome article. Probably you could create a package with one of the blocking, non blocking and semi blocking transformations and explain as to what exactly is happening @ runtime for each of the transformations.
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nice good article
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Nice.. cleared my doubts
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Nice article,easy to undesrstand.
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Good post !
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Good
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good explanation and good content.
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Good information on comparing various transformations
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Very Good
Clearly Understandable……..:-)
Thank You
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Very good..
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very good article
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The multicast component is partially blocking, not non-blocking.
http://social.technet.microsoft.com/wiki/contents/articles/7392.ssis-multicast-transformation.aspx
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Also, the script component can be either of the 3 i think?
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HI,
Let say i have first name and last name as my input column but i m passing Name i.e first name + last name as a single record (by concatanatin).So in this my expression is recieving 2 inputs but one output.So can u please xplain why still expression is non blocking
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Hi Waseem,
No of records IN== No of records out (i.e 10(Firstname+Lastname)=10 Name) So 10 input records 10 output records
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Text is not visible properly. There are lot of hyperlinks on text.Please remove ads on top of text
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Thanks for the wonderful post.
Any idea why “Row sampling” is blocking task whereas “Percentage sampling” is non-blocking?
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Lot of Ads in Site area ppearing over content in the website. Can you please move ads to other places so that content should be clearly visible.
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Nice Article
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so clear picture
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Thanks.it’s clear my doubt..
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It’s Very GOOOOOOOOD Article
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Short and Crisp ..Thanks 🙂
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Great article
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Little confusion
for Synchronous Row input = Row output
Then how Percentage Sampling can be Synchronous
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Is union all is semi-blocking transformation? I think it is non-blocking transformation because it does not need another buffer to store result.
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Really nice article . thanks.
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Very good article. Useful..
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Nice Article
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it’s Good
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It’s useful and good.
Thanks
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That’s really interesting, considering it reverses the customary meaning of synchronous and asynchronous. Typically calls that are synchronous are blocking calls.
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really good article
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Nice explanation.
Thanks a lot.
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Very good explanation. clear and precise
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very useful info. thank you
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Fantastic article
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Nice Article 🙂
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Very basic but powerful explanation nice job
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You mentioned, All source adapters are asynchronous(two outputs) but you mentioned Lookup , multi cast(these will have more outputs..matched/non matched..etc) are non blocking transformations. Is not this contradict?
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Useful article
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Hi,
you done good job.
nice explanation on blacking transformation.
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ohhh its soo goood
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Excellent !
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