A Trivial plan is created when SQL Server really doesn’t have any choice in how it’s going to execute. Here’s an example from the StackOverflow database with the indexes removed: There really isn’t any choice but a clustered index seek. It’s the only index and its about as effective as we can get given we’re filtering on […]
Tickets. Each one helps make the solutions we support more feature complete, bigger, faster, and fixed-er. This month’s invitation from Brent asks us to describe one of the last tickets which was closed to give an insight into our day to day. As an introduction: this is a response from a Development DBA who is relatively new into a […]
Blocking in SQL Server will reduce throughput. Excessive blocking can be cause bottlenecks on our environments so helping to mitigate it. Here we’re going back to basics to look at how it happens and how having effective indexes can reduce it. Blocking We’ll start off with an example of blocking. Here’s our customer table and […]
The DISTINCT clause in a query can help us quickly remove duplicates from our results. Sometimes it can be beneficial to stop and ask why. Why do we need to use the clause, why are we receiving duplicates from our data? I see this typically due to a JOIN being used where we don’t really want all of those results. This could […]
Deadlocks are an enduring feature of SQL Server. They’ve been a source of pain for many over the years and there are various ways to diagnose, mitigate or resolve them. Here I want to demonstrate approach I haven’t seen discussed – using an application lock to segregate processes. An example where I’ve used this effectively […]
Looking back at the year that has been and the year ahead
This month’s invitation from Reitse asks us to talk about learnings from abandoned or failed projects. This one will sit somewhere squarely between those two points. It was an opportunity to learn about scalability. Let’s set the scene. A point of sale system being rolled out across hundreds of physical locations. Transaction data collected each night to […]
In the previous post we looked at the functions TRY_CAST, TRY_CONVERT, and TRY_PARSE and how they compared. I wrapped up and said that my preference for new developments would be to use TRY_PARSE due to the tighter control which it provides us. As with everything in SQL Server however, there is no ‘best’ approach, it depends. I therefore wanted […]
In the previous post we looked at how ISNUMERIC and TRY_CAST work and why we may want to utilise the latter when building validation for our data. When SQL Server 2012 rolled around it wasn’t only TRY_CAST which was added, we also had TRY_CONVERT and TRY_PARSE introduced too. Here we’re going to look at how […]
Data validation is key when ingesting from external sources. As we can’t always be certain of data quality we inevitably find bad data which needs to be handled. Here I wanted to look at a couple of options for validating numeric data. Here’s the scenario – we’ve got data which may have been received via […]
Andy Brownsword 