In this article we look at different use cases for columnstore indexes like when performing SQL Server count * queries.
As SQL developers, we tend to think of performance tuning in terms of crafting the best table indices, avoiding scalar and table valued functions, and analyzing query plans (among other things). But sometimes going back to the spec and applying some properties of elementary math can be the best way to begin to improve performance of SQL queries which implement mathematical formulas. This article is a case study of how I used this technique to optimize my SQL implementation of the Inverse Simpson Index.
Introduction Instead of going straight into the topic of the Query Store, I would like to start this Stairway Series by mentioning a few performance tuning scenarios that are very common to production DBAs. I think most of us have been in one of these situations at some time: An application experiencing slowness after a […]
The IGNORE_DUP_KEY option for unique indexes specifies how SQL Server responds to an attempt to INSERT duplicate values: It only applies to tables (not views) and only to inserts. Any insert portion of a MERGE statement ignores any IGNORE_DUP_KEY index setting.
Far too often, an indexed view is created without consideration for the costs of the indexed view. In this article, Jason Brimhall covers some of the more important costs that are frequently overlooked when considering an indexed view as a performance panacea.
The contents of the SELECT, WHERE and ORDER BY clauses are all a matter of determining the story you need to tell. I was asked to look into an issue recently where a 40-core SQL Server instance was fully utilizing a one node over all others...
It’s surprisingly useful to know the number of active sessions on each of the databases on your servers. With a bit of SQL, we can create a custom metric to track how many sessions recently performed reads or writes on a database.