Columnstore Segment Elimination Pains

Niko Neugebauer shows us two pain points with row group (segment) elimination on clustered columnstore indexes:

Still this gives us processing of just 1 Segment with 253 lob logical reads vs 6 Segments and 2669 lob logical reads in the original query.

But wait, that’s not all! It can get significantly worse!
Let’s use the inequality search with the OR condition, to see what happens – should be safe, right ?

Spoilers:  it’s not safe.  I’ve been burned on the Min + Max issue that Niko shows, where you’d think that it could eliminate all segments except for the first and last, but that’s not how the process works today.

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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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Trace Flag 834 And Columnstore Tables

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