SQL Server Performance Forum – Threads Archive
Regarding Broadcast Parallelism.Hi, I have written a Query that shows a stream of Broadcast Exchange operator Parallelism. I can’t understand the basic reason behind it as I know mainly three types of Exchange Operators, viz Distribute, Gather and Repartition. Can anybody highlight regarding this type of Parallelism as I am not able to find any clue regarding it even in BOL. Regards, Arindam Ganguly
Have you set max degree of parallelism?
Are there any changes to the environment recently? Satya SKJ
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Hi Satya, I have checked the maximum degree of parallelism set to 0 ? Should I change it. If it is then to what value ? Pls advise. Regards,
My guess about Broadcast operators is that they send copies of all the data from a single stream out to multiple streams which kicks off the parallel operations. I have seen this in a hash join where the broadcast feeds into the building of a parallelised hash table. I guess it’s a newish exchange operator (hence not in BOL) that increases the number of alternative query plans to optimize between. I have only seen it used when the amount of data being broadcast was quite small. Regards