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The Risk of Changing MaxDOP

Erik Darling recommends caution:

Like in yesterday’s post about Cost Threshold For Parallelism, changing MAXDOP settings will have a universal effect on the workload.

This is true whether you change it at the server level for all databases, or at the database level using a database scoped configuration for a single database.

It is a guardrail to prevent unwanted conditions as a whole, like excessive concurrent parallel queries causing worker thread starvation (THREADPOOL waits), or just pushing CPU to 100% for extended periods of time.

Read on to see what Erik recommends you think about after any MaxDOP change.