What’s a Key Lookup?
One of the easiest things to fix when performance tuning queries are Key Lookups or RID Lookups. The key lookup operator occurs when the query optimizer performs an index seek against a specific table and that index does not have all of the columns needed to fulfill the result set. SQL Server is forced to go back to the clustered index using the Primary Key and retrieve the remaining columns it needs to satisfy the request. A RID lookup is the same operation but is performed on a table with no clustered index, otherwise known as a heap. It uses… Continue reading
Women in Tech Talk Tech
March is Women’s History Month, to celebrate the PASS Women in Technology Virtual Group (@PASS_WIT) held a webcast featuring prominent woman in the Data Platform community. I had the pleasure of being one of five panelists alongside these amazing women Lori Edwards (B|T), Malathi Mahadevan (B|T), Kellyn Pot’Vin-Gorman (B|T), and Catherine Wilhemsen (B|T). Discussion ranged from direct technical topics to what it’s like being a woman in tech. Women took turns providing advice around having a degree and/or certification to succeed in tech. We discussed how to keep up with advances in the field and skills that technologists should have.… Continue reading
Enable Mail Profile – Back to Basics
I’ve seen many people go through the trouble of setting up database mail and configuring SQL Agent Alerts only to realize it’s not working. The reason in the cases I’ve seen is because they have simply neglected to assign a mail profile to SQL Agent. This is way more common than you would think, thus I wrote this quick blog. This check box and drop down can sometimes lead to hours of troubleshooting if you don’t know where to look. In order to receive the alerts, you must enable a mail profile. This would be the profile created during the… Continue reading
How Your Hypervisor Can Impact Your CPU
Recently I had a client complain of chronic high CPU utilization. The performance of their SQL Server had degraded, and it appeared to be related to higher than normal CPU utilization in conjunction with symptoms of unresponsive user queries. The root cause was twofold—a third party hosting provider had overallocated virtual processors on the physical host where the virtual machine (VM) running SQL Server was residing, as well as a recent upgrade from a version of VMWare that was not patched for Spectre and Meltdown. The host had 16 physical cores and was hyperthreading (making it effectively 32 cores) until… Continue reading