Merging With Columnstore

Niko Neugebauer does not like the MERGE statement when applied to columnstore indexes:

This blog post is focused on the MERGE statement for the Columnstore Indexes, or as I call it – the worst enemy of the Columnstore Indexes. It is extremely difficult to imagine some statement or way of making the worst out of the Columnstore Indexes, if not the infamous MERGE statement. Why ? Because it is not only making Columnstore Indexes perform slow, it will make them perform MUCH SLOWER then any Rowstore Indexes. Yes, you have read right – slower then ANY_ROWSTORE_INDEXES. In fact, this should be a hint that one should apply to the Merge statement, when it is executed against Columnstore Indexes! 🙂
I decide to dedicate a whole blog post on this matter, mainly to warn people of this pretty problematic statement – I hope not to see it being used for Columnstore Indexes in the future!

There is very little room for misunderstanding in Niko’s post.

Related Posts

Batch Mode Memory Fractions

Joe Obbish explains what memory fractions are and how incorrect calculations can lead to tempdb spills: There’s very little information out there about memory fractions. I would define them as information in the query plan that can give you clues about each operator’s share of the total query memory grant. This is naturally more complicated for […]

Read More

Digging Into The In-Memory Columnstore Location

Niko Neugebauer does some investigation into where, exactly, memory-optimized columnstore data goes: This is a rather simple blog post that is dedicated to the theme of the In-Memory Columnstore Indexes location. This has been a constant topic of discussion over a long period of time, even during the public events – and there is a […]

Read More

Categories

February 2017
MTWTFSS
« Jan Mar »
 12345
6789101112
13141516171819
20212223242526
2728