Avoid Scalar Functions In Computed Columns

Daniel Hutmacher shows why you should not include scalar functions inside computed column definitions:

Scalar functions can be a real headache when you’re performance tuning. For one, they don’t parallelize. In fact, if you use a scalar function in a computed column, it will prevent any query that uses that table from going parallel – even if you don’t reference that column at all!

Read on for a demonstration.

Related Posts

Replaying Workloads with WorkloadTools

Gianluca Sartori shows an example of using the WorkloadTools application to replay a workload, including where the analytics server cannot directly access the production database: Regardless of the method that you decided to use, at the end of the replays, you will have two distinct sets of tables containing the workload analysis data, sitting in […]

Read More

Troubleshooting Query Performance Changes

Erin Stellato walks us through a troubleshooting guide when users complain about poorly-performing queries: This is tale of troubleshooting… When you unexpectedly or intermittently encounter a change in query performance, it can be extremely frustrating and troublesome for a DBA or developer. If you’re not using Query Store, a third-party application, or your own method […]

Read More

Categories

January 2018
MTWTFSS
« Dec Feb »
1234567
891011121314
15161718192021
22232425262728
293031