The name of the “SQL Statistics \ Batch Requests/sec” counter is confusing: exactly what is a request? The request is the WHOLE batch. See a demo of this counter in this quick 5 minute video.
Batch mode was introduced as a way to help SQL Server process data from columnstore indexes faster. The whole idea with columnstore is that you pull big compressed sets of rows out for aggregation or other operations in big chunks.
Batch mode is a way that operators can work on a “batch” of up to 900 values at a time, instead of working on individual rows. Batch mode can reduce the overhead of metadata and make more efficient use of your CPUs.
Every now and again, I need use a global temporary table for some testing or demo code.
Each time I do, I stumble a little bit when it comes to checking for the existence of the global temp table, in order to make my code re-runnable.
Sometimes you need to compare lots of counters at once - for example, counters that report at the database level. This can be frustrating in “Line” view, but the “Report” view in perfmon makes life much simpler.
I recently did a Dear SQL DBA episode answering a question about lock timeouts and memory in SQL Server. I really enjoyed the episode, and thought it would be fun to follow up and show what it looks like if SQL Server doesn’t have enough memory to allocate locks.
The problem: by default, the Performance Monitor application in Windows doesn’t remember which counters you like to use.
This can mean a lot of clicking every single time you open perfmon.
You can enable and disable trace flags either globally or per-session in SQL Server.
This makes it seem like perhaps if you enable optimization trace flag 4199 globally for all sessions, you might be able to disable it per-session.
But that’s NOT how it works.
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