Columnstore Partitioning

Niko Neugebauer warns against partitioning small tables with clustered columnstore indexes:

Needless to say that looking at the execution plans you notice that the actual execution plan shows 10 times difference between them, even though both tables contain the very same data!
The query cost for the partitioned table is staggering – it is around 10 times bigger (~8.8) vs (~0.81) for the first query.
The execution times reflect in part this situation: 12 ms vs 91 ms. Non-partitioned table performs almost 9 times faster overall and the spent CPU time is reflecting it: 15 ms vs 94 ms. Remember, that both tables are Columnstore Indexes based ! Partitioning your table in a wrong way will contain a huge penalty that might not be directly detectable through the execution plan of the complex queries. Well, you might want to use the CISL, just saying

If you can’t fill a single rowgroup, your partition is too granular.  Even then, I’d like to see double-digit rowgroups per partition, though that’s just me.

Related Posts

Causing Error 666 When Loading Into Columnstore Index

Joe Obbish has moved into Erik Darling’s Internet Basement and has a doozy of a first post there: I need to find a relatively efficient way to advance the CSILOCATOR because I need to do it over 2 billion times, if my theory is correct about the maximum allowed value. Both updating all of the […]

Read More

Table Partitioning: WAIT_AT_LOW_PRIORITY on Standard Edition

Michael Bourgon explains what the WAIT_AT_LOW_PRIORITY option does with table partitioning and that it is available in Standard Edition: But how about WAIT_AT_LOW_PRIORITY?  That was introduced in 2014 to make table partitioning deal better with That-Dude-From-Accounting-Who-Kicks-Off-A-Massive-Query-On-Friday-at-5pm, which causes partitioning to hang on Saturday when you’re trying to add and remove partitions. Read on for a […]

Read More

Categories

January 2017
MTWTFSS
« Dec Feb »
 1
2345678
9101112131415
16171819202122
23242526272829
3031