Database Reference
In-Depth Information
Query Performance Tuning
One of the main reasons for building Analysis Services cubes as part of a BI solution is
because it should mean you get better query performance than if you were querying
your relational database directly. While it's certainly the case that Analysis Services
is very fast, it would be naive to think that all of our queries, however complex, will
return in seconds without any tuning being necessary. This chapter will describe
the steps you'll need to go through in order to ensure your cube is as responsive as
possible, covering the following topics:
Partitioning measure groups
Building aggregations
Tuning MDX calculations and queries
Using caching to your advantage
Understanding Scale-out options
This chapter should be read in conjunction with the very detailed white
paper, "The Analysis Services 2008 R2 Performance Guide", which can
be downloaded from http://tinyurl.com/ssasR2perf .
Understanding how Analysis Services
processes queries
Before we start to discuss how to improve query performance, we need to
understand what happens inside Analysis Services when a query is run. The two
major parts of the Analysis Services engine are:
The Formula Engine : This part processes MDX queries, works out what data
is needed to answer them, requests that data from the Storage Engine, and
then performs all calculations needed for the query.
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