Parallel Insert-Select

Arvind Shyamsundar looks at parallel insertion using the INSERT SELECT pattern:

For row store targets, it is important to note that the presence of a clustered index or any additional non-clustered indexes on the target table will disable the parallel INSERT behavior. For example, here is the query plan on the same table with an additional non-clustered index present. The same query takes 287 seconds without a TABLOCK hint and the execution plan is as follows

This post goes into detail on when you can expect parallelism in rowstore and columnstore insertions.  I highly recommend reading it.

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