SQL 2012 was a big release for working out the median in SQL Server, with the advent of the function PERCENTILE_CONT(). It’s a very elegant way of working out the median (hint, that’s the 0.5 point), even though it’s not actually an aggregate function, as I’ve written before. Plus – it doesn’t even perform well. About a year ago, Aaron Bertrand ...

Today LobsterPot Solutions sets a new first. We are the only company to ever employ three current Australian SQL MVPs, giving us four awardees in total. Congratulations to Martin Cairney who joins Julie Koesmarno (AUS), Ted Krueger (USA) and me (AUS) as recipients of this prestigious award. This demonstrates LobsterPot's ongoing commitment to the ...

This is a white paper that I put together recently about APS / PDW Query Optimisation. You may have seen it at http://blogs.technet.com/b/dataplatforminsider/archive/2014/11/14/aps-best-practice-how-to-optimize-query-performance-by-minimizing-data-movement.aspx as well, but in case you haven’t, read on! I think the significance of this paper is ...

If you’ve ever done spatial work with SQL Server, I hope you’ve come across the ‘nearest’ problem. You have five thousand stores around the world, and you want to identify the one that’s closest to a particular place. Maybe you want the store closest to the LobsterPot office in Adelaide, at -34.925806, 138.605073. Or our new US office, at ...

There is no equivalent to the SSIS Lookup transformation in T-SQL – but there is a workaround if you’re careful. The big issue that you face is about the number of rows that you connect to in the Lookup. SQL Books Online (BOL) says: If there is no matching entry in the reference dataset, no join occurs. By default, the Lookup transformation ...

A post I’ve been meaning to write for a while, good that it fits with this month’s T-SQL Tuesday, hosted by Joey D’Antoni (@jdanton) Ever since I got into databases, I’ve been a fan. I studied Pure Maths at university (as well as Computer Science), and am very comfortable with Set Theory, which undergirds relational database concepts. But I’ve ...

This past weekend saw the first SQL Saturday in Melbourne. Numbers were good – there were about 300 people registered, and the attendance rate seemed high (though I didn’t find out the actual numbers). Looking around during the keynote, I didn’t see many empty seats in the room, and I knew there were 300 seats, plus people continued to arrive as ...

There are quite a few reasons why an Index Scan is better than an Index Seek in the world of SQL Server. And yet we see lots of advice saying that Scans are bad and Seeks are good. Let’s explore why. Michael Swart (@MJSwart) is hosting T-SQL Tuesday this month, and wants people to argue against a popular opinion. Those who know me and have heard ...

I feel like every database project has major decisions now, which are remarkably fundamental to the direction that’s going to be taken. And it’s almost as if new options appear with ever-increasing frequently. Consider a typical database project, involving a transactional system to support an application, with extracts into a data warehouse ...

Suppose your SQL table has a bunch of spatial points (geographies if you like) with an order in which they need to appear (such as time) and you want to convert them into a LineString, or path. One option is to convert the points into text, and do a bunch of string manipulation. I’m not so keen on that, even though it’s relatively ...