New Columnstore Trace Flags

Niko Neugebauer looks at a few trace flags which modify columnstore index behavior:

Starting with SQL Server 2016, if you have enough RAM and suffering from the TempDB Spills that do have a significant impact on your workload, then you can enable the Trace Flag 9389 that will enable Batch Mode Iterators to request additional memory for the work and thus avoiding producing additional unnecessary I/O.

I am glad that Microsoft has created this functionality and especially that at the current release, it is hidden behind this track, and so Microsoft can learn from the applications before enabling it by default, hopefully in the next major release of SQL Server.

There’s a lot of good stuff in here.  Read the whole thing.

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