While working with PerfMon data recently I ran into an interesting error when I tried to view it overlayed against a Trace file. If you’re not familiar with that process, I recommend Brad McGehee’s article Correlating SQL Server Profiler with Performance Monitor. I had opened a Trace file and selected a PerfMon file to import. …
Monthly Archives: March 2012
Isolation Levels and the Effects on Select Statements, Part II
Last week I wrote a post on Isolation Levels and the Effects on Select Statements, and I had a conversation on Twitter with Rob Farley ( b | t ) regarding one of my explanations. For READ COMMITTED, I had written the following: If data is being modified by a transaction, any subsequent select statement…
Gratitude
Yesterday afternoon I drove up to Southfield, Michigan to present to the Southeast Michigan SQL Server User Group. Joe Fleming contacted me and asked if I would present my Baselines session, which I presented at the PASS Summit last fall. I usually don’t pass up a chance to go to Michigan, and this was the…
Isolation Levels and the Effects on Select Statements
Database locking is a fundamental concept in SQL Server that every Database Administrator and Database Developer should understand. SQL Server has a pessimistic locking model because it was built for an OLTP environment and assumes that updates will occur frequently. For a developer, this is important to understand in terms of concurrency: how many users…
