The idle CPU condition tells SQL Server Agent when the CPUs are quiet enough to start a job. This post shows where to set it, how the two numbers work and how to create the schedule. It also reads the CPU history of your server in T-SQL, so you can choose values that the server can actually meet.
SQL SERVER – Active Parallel Requests and Cached Parallel Query History
I Identify parallel running requests separately from parallel queries recorded in the cache. Those lists answer different performance questions.
SQL SERVER – Is Stream Aggregate is Same as Gather Streams of Parallelism?
Is Stream Aggregate is Same as Gather Streams of Parallelism? – This was one of the brilliant questions I had received during my recent engagement.
ENABLE_PARALLEL_PLAN_PREFERENCE Limits: Rows Per Thread
The ENABLE_PARALLEL_PLAN_PREFERENCE limits are easy to miss: the hint can’t make every query parallel, and it can’t spread rows evenly over the threads. This post proves three limits from the last actual plan of demo queries, with the rows each thread processed and the reason a plan stays serial.
Force a Parallel Plan: ENABLE_PARALLEL_PLAN_PREFERENCE Hint
To force a parallel plan for one query, add the ENABLE_PARALLEL_PLAN_PREFERENCE hint to its OPTION clause. This post shows why a cheap query stays serial, runs a demo query with and without the hint, proves the difference from the last actual plan, and explains why the hint belongs in a test and not in every query.
Runnable Sessions in SQL Server: What to Check Next
Runnable sessions are sessions that have everything they need except a free CPU. This post counts requests by status, checks that SQL Server can see every processor, reads the settings that cap CPU use, and lists the statements waiting in the queue, so a long queue next to a half idle CPU stops being a puzzle.
Windows Power Plan for SQL Server: Use High Performance
The Windows power plan decides how fast the processors run, and an energy saving plan can slow SQL Server without raising any error. This post shows how to check the active plan, how to switch it and undo the change, and how to time the difference with a repeatable T-SQL loop.