Memory-Optimized Table Maintenance

Ned Otter has a great post looking at what you can and cannot do with memory-optimized tables containing certain types of indexes:

Now, let’s attempt to create a NONCLUSTERED COLUMNSTORE INDEX:

ALTER TABLE dbo.InMemADD
ADD INDEX NCCI_InMem NONCLUSTERED COLUMNSTORE (col1);

Msg 10794, Level 16, State 76, Line 76
The feature ‘NONCLUSTERED COLUMNSTORE’ is not supported with memory optimized tables.

It fails because we can only create a CLUSTERED columnstore index (CCI). For 25 years, Microsoft SQL Server differentiated between indexes that physically ordered data on storage (CLUSTERED) and those that did not (NONCLUSTERED). Unfortunately, they chose to ignore that pattern when creating the syntax for memory-optimized tables; using the word CLUSTERED is required when creating a columnstore index on memory-optimized tables. 

It’s a great post with plenty of trial and error.

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