Memory-Optimized Columnstore

Niko Neugebauer clears the air regarding memory-optimized columnstore tables:

I would like to dedicate this blog post to the Memory-Optimised (also known and LOVED as Hekaton) Columnstore Indexes and their limitations in SQL Server 2016.
Disclaimer: the Memory-Optimised Technology is the ground-breaking development, which will be truly appreciated only in the next couple of years, and it has its incredible use cases (and maybe I will be blogging more about this space in the next couple of months), but people needs to understand that mapping InMemory Columnstore Indexes to disk-based Columnstore Indexes 1:1 is a very wrong idea, and that because InMemory technology is significantly younger and less stable than Columnstore Indexes – there are some very significant hidden cornerstones.

It’s important to read this post as “this is not yet a fully-mature product” rather than “this will always be worse.”  But it’s just as important to understand the limitations of the product and not think you’re getting something that you aren’t.

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Reserved Memory Allocation Waits And Trace Flag 834

Joe Obbish has another post looking at sub-optimal columnstore index performance: It is possible to see a scalability bottleneck in the form of high average wait time for the RESERVED_MEMORY_ALLOCATION_EXT wait if a highly concurrent workload is run on a server that consumes memory with batch mode operators. I believe that the severity of the bottleneck depends […]

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Columnstore And Merge Replication

Niko Neugebauer tests whether merge replicated tables can use columnstore indexes: Adding this table to the publication will end up with the following, self-explaining error message, being very clear that the Clustered Columnstore Indexes are not supported for the Merge Replication[.] There is no surprise here, as the same Clustered Columnstore Indexes are not supported […]

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