Mike West recently posted a rather active thread on LinkedIn about databases with more than one transaction log file. Eventually, I realised that the full answer to the question: “When does it make sense to add another log file to a database for performance reasons?” is complex enough that it needs a blog available for future reference.
The TPC-H benchmark is often used a method for customers to evaluate data warehouse products to make purchasing decisions. Because it is such a crucial benchmark, it is important to understand the challenges it presents for database vendors. Unfortunately, the public information about tuning for TPC-H is rather sparse and it is generally hard to come by good documentation. Vendors do not like to be compared with other vendors – so their secrecy is understandable.
In this blog series, I will try to shed some light on the TPC-H benchmark, what I think is wrong with it, and provide some of my thoughts about the challenges you face when tuning it.
As you may have noticed, I have been creating standardised feeds of ISO data lately. In case you missed it, you can find the data here: http://kejser.org/resources/free-data/.
While I was working with this data, I began to notice a pattern: Windows has very poor support for UTF-8. In this post, I am going to be complaining loudly about this!
Lately, I have been doing more and more work in my native OSX image. And I am really loving it.
However, being an old Windows user, I find a lot of habits hard to break and I constantly find myself wanting the standard Bash command line to behave just a little more like good old DOS. To avoid the same typing error over and over again, I found these modifications to be useful. I am sharing them here in hope they may help other people who are transitioning from Windows. Continue reading…
The revealed wisdom in the SQL Server community has generally been that query hints should only be used as a last resort. For a complete novice of SQL Server, I would agree. But to call avoiding query hints a “best practise” is taking it too far.
For anyone with a little experience who knows what they are doing, I find that query hints are not only a good reactive solution, they are a proactive, design time, tool.
Most database systems need some form of log table to keep track of events, for example for auditing purposes. To avoid the log growing forever, it is often a good idea to regularly rotate old log entries out of this table. For small log tables, running a DELETE statement works well for this purpose. However, as the log throughput grows, it is often preferable to use partition switching instead. In this blog, I will show you an implementation of a rotating log table.
When building a data warehouse, you often find yourself needing to move data that is the result of a query into a new table. In SQL Server, there are two way to do this efficiently:
- SELECT INTO
- INSERT INTO WITH (TABLOCK)
While both techniques allow to you achieve bulk logged (i.e. fast) inserts, I am going to argue that method 2 is preferable in most situations.
In the quest for 100% uptime, a great many hours must be invested in careful design. Even when you think you have eliminated every Single Point Of Failure (SPOF) – something new always shows up. It get’s worse: All this the effort is multiplied if you want to BOTH achieve high availability AND run a system at high speed.
In this blog, I will share some lessons we learned the hard way while tuning our high speed SQL Server mirror.
I am a ten finger typist doing around 5 strokes/second – though I do make a lot of mistakes. I learned the craft on a good old fashioned typewriter. The world has moved; unfortunately, keyboards have not. There are keys left in a modern keyboard that are simply of no use anymore – grim reminders of the age of typewriters or just leftovers from ancient (before 2000) times in computers.
Two such keys are CAPS LOCK and INS. As fast typist, you simply don’t need CAPS LOCK. And I have no idea what anyone needs INS for anymore. In other words, hitting either of those keys is always an error. Fortunately, there is a solution that does not require you to take a screwdriver to your keyboard: you can turn those keys off.
The attached registry file will do this nicely. Just unzip and apply.
Featured image: The legendary IBM M13 in Stealth Black.