sp_BlitzCache™ Result: Query Cost Near the Cost Threshold for Parallelism

Poorly performing queries have been found in the plan cache where the query cost is within 10% of the cost threshold for parallelism. Queries that are right on the edge of the cost threshold for parallelism can end up going parallel. It’s also possible that changes to the data may change the execution plan that SQL Server selects.

How to Fix the Problem

There may not be anything to fix. But, these queries do need additional investigation and monitoring – these queries may already be going parallel or a simple change may send those queries parallel.

Investigate high cost items like index scans, use of functions in search predicates, and other things that won’t scale.