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Checking out SQL Server via empirical data points
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When you have some data on a SQL Server instance (say SQL01) and you want to move the data to another SQL Server instance (say SQL02) through openquery(), you can either push the data from SQL01, or pull the data from SQL02. To push the data, you can Read More...
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In an earlier post , I highlighted that linked server security configuration can have a huge performance impact, and complained that this was not properly documented in SQL Server Books Online and filed a Connectitem for this. Good news is that in Books Read More...
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It’s a well known good practice to control the batch size when you perform large data changes. For instance, you may need to purge a large amount of data monthly, and if you delete them all in one shot, you may blow up your transaction log. Therefore, Read More...
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In SQL Server, it is rather handy to retrieve data from a different SQL Server instance and use the result locally in another SQL statement for further processing. In theory and in the set purists’ fantasy land, it shouldn’t matter where you get your Read More...
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Is it better to move data to procedures or move procedures to data? The answer is, of course, “it depends.” Let’s consider a scenario where you have two SQL Server instances: ServerA and ServerB, and you have a procedure on ServerB (call it procB), but Read More...
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I posted the following SQL Server challenge yesterday: Describe a reproducible workload that would see significant throughput improvement when trace flag 1118 is enabled. In response, Konstantin Korobkov wanted to know whether the number of data files Read More...
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SQL Server can run in one of two modes: thread mode or fiber mode. By default, SQL Server runs in thread mode in which a SQL Server worker is associated with a Windows thread throughout all phases of its execution. This can be changed with the sp_configure Read More...
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In my previous post on the performance impact of having a large number of virtual log files (VLFs) in a transaction log, I showed that a large number of VLFs could be very bad for SQL Server 2008 performance. The test workloads were large batch delete, Read More...
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It is generally known that having a large number of virtual log files (VLFs) in a database transaction log is undesirable. A blog post by the Microsoft support team in Stockholm showed that a large number of virtual log files could seriously lengthen Read More...
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Lies, damned lies, and statistics! If you have read my three previous posts ( 1 , 2 , 3 ), you may walk away with an impression that on a drive presented from a high-end enterprise class disk array, Windows file fragmentation does not have a significant Read More...
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There were discussions on disk misalignment on this site. See my previous post on “ Performance Impact of Disk Misalignment ”, and Kevin Kline’s blog on “ How to Improve Application and Database Performance up to 40% in One Easy Step ” But thanks to Jimmy Read More...
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What does it mean if you see a high percentage of signal waits? Thanks to Microsoft whitepapers, presentations, and blogs, everybody would say it implies CPU pressure. Well, almost everyone except Mario Broodbakker, whose excellent blog “ Taking the guesswork Read More...
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A frequently asked question is what counters should be included in a SQL Server baseline. The discussion then quickly proceeds to define a set of perfmon counters to be logged as the performance baseline. And often, people seem to have an urge to try Read More...
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To many, this is an old and tired topic, and any more mention of ad hoc queries versus parameterized queries may just send someone off the deep end. But recently I was doing some Oracle benchmarks, and the benchmark tool reported ~1,200 transactions per Read More...
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Regardless of the DBMS make or model, the transaction throughput curve of a database system is often shaped like a trapezoid. As the load level goes up initially, so does the transaction throughput. As the load level continues to go up, the transaction Read More...
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