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Rob Farley - Owner/Principal with LobsterPot Solutions (a MS Gold Partner consulting firm), Microsoft MVP (SQL Server) and leader of the SQL User Group in Adelaide, Australia. Rob is also a Director of PASS, and runs training courses around the world in SQL Server and BI topics.
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It’s very easy to get in the habit of imagining the way that a query should work based on the Logical Order of query processing – the idea that the FROM clause gets evaluated first, followed by the WHERE clause, GROUP BY, and so on – finally ending with Read More...
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Tables are only metadata. They don’t store data. I’ve written something about this before, but I want to take a viewpoint of this idea around the topic of joins, especially since it’s the topic for T-SQL Tuesday this month. Hosted this time by Sebastian Read More...
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Take a look at this query plan. Yes, that arrow indicates a single row. This is an Index Seek, returning a single row. And yet it’s rubbish. That’s right – it’s rubbish! In fact, I had to provide a hint for it to use this index. A table scan would’ve Read More...
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My good friend Simon Sabin used the term ‘invertability’ on a Connect item he logged today. Essentially, Simon’s noticed that there are lots of people that use year(someDate), but that the system doesn’t understand that this function doesn’t affect the Read More...
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No, this post has nothing to do with airport security, and nothing to do with marijuana. Being honest, this post is only half about Hash Matches and Probe Residuals. It’s more about the types of predicates you can see mentioned in a SQL Server Execution Read More...
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I know that everyone misses this, because I’m yet to find someone who doesn’t have a bit of an epiphany when I describe this. When tuning Data Flows in SQL Server Integration Services, people see the Data Flow as moving from the Source to the Destination, Read More...
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SQL Server is quite remarkable in a bunch of ways. In this post, I’m using the way that the Query Optimizer handles LIKE to keep it SARGable, the Execution Plans that result, Collations, and PowerShell to come up with the Swedish alphabet. SARGability Read More...
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When I’m at the PASS Summit in Seattle this week, I will need to remember that I can’t just step onto the road if I’m walking along the footpath on the right-hand side. In the UK and Australia, where we drive the correct side, it’s fine (just don’t tell Read More...
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This month’s T-SQL Tuesday has me caught slightly unawares. I’m in the UK, having come over for SQLBits , and I’m left writing this with only a few hours to go. The theme this time is on misconceptions in SQL, and this fits nicely with SARGability – one Read More...
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No really – hear me out. Of course you create tables, and you query tables, and we say that data is stored in tables. The table is (rightly) a fundamental part of relational theory. But I find that when I think about queries and how they run, I need to Read More...
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(Reposted from my msmvps.com blog ) A recent discussion on Twitter about a query that Denny Cherry was looking at led to this post by Josef Richberg: http://josef-richberg.squarespace.com/journal/2010/1/28/is-a-case-statement-considered-sargable.html Read More...
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(Reposted from my msmvps.com blog ) SARGable is an adjective in SQL that means that an item can be found using an index (assuming one exists). Understanding SARGability can really impact your ability to have well-performing queries. Incidentally – SARGable Read More...
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