For some reason, the title of this blog post makes me grin because it evokes a mental image of one guy trying to comically strangle another guy.  But I digress…   Speaking at a user group meeting recently, an attendee asked whether the mirroring process had any capability to speed up or slow down its workload according to the amount of ...

If you're well-versed in using PerfMon, I'd like to hear about the counters that you use regularly and what constitutes a good or bad value.  However, it's a rare individual who knows their way around PerfMon and its multitude of performance objects and counters.  Which ones should you track?  And even if you know the ...

I guess that many people using UPDATE … FROM on a daily basis do so without being aware that they are violating all SQL standards.   All versions of the ANSI SQL standard that I checked agree that an UPDATE statement has three clauses – the UPDATE clause, naming the table to be updated; the SET clause, specifying the columns to change and ...

What does it mean if you see a high percentage of signal waits? Thanks to Microsoft whitepapers, presentations, and blogs, everybody would say it implies CPU pressure.   Well, almost everyone except Mario Broodbakker, whose excellent blog “Taking the guesswork out of SQL Server performance profiling Part 2” shows us that SQL Server signal ...

A frequently asked question is what counters should be included in a SQL Server baseline. The discussion then quickly proceeds to define a set of perfmon counters to be logged as the performance baseline. And often, people seem to have an urge to try to reduce the baseline to a small number of perfmon counters that may cover processors, memory, ...

To many, this is an old and tired topic, and any more mention of ad hoc queries versus parameterized queries may just send someone off the deep end.   But recently I was doing some Oracle benchmarks, and the benchmark tool reported ~1,200 transactions per second. A transaction in this case was a simple SELECT with a join on the indexed ...

Regardless of the DBMS make or model, the transaction throughput curve of a database system is often shaped like a trapezoid. As the load level goes up initially, so does the transaction throughput. As the load level continues to go up, the transaction throughput will reach a plateau. After the load level is cranked up still further, the ...

The best documentation on the I/O behavior of SQL Server checkpoints is found in SQL Server 2000 I/O Basics by Bob Dorr. In particular, you should read the following carefully: SQL Server uses the following steps to set up another page for flushing and repeats for up to 16 total pages inclusive of the first page. Do a hash lookup for the ...

Within the SQL Server community, there is so much publicity on T-SQL set-oriented processing as good practice and the use of T-SQL cursors as bad practice that  T-SQL cursors are effectively being seen as a plague to be avoided when in fact it's not the use of T-SQ cursors, but their misuse, that should be avoided. To be fair, I must say that ...

In response to my previous blog post--Performance Impact: Setting a Database to Read Only, Shailesh Khanal mentioned that he observed significant performance degradation from READ COMMITTED SNAPSHOT OFF to ON for a read-only workload. This is counter intuitive since there is nothing in the version store if only SELECT statements are ...