THE SQL Server Blog Spot on the Web

Welcome to SQLblog.com - The SQL Server blog spot on the web Sign in | |
in Search

Browse by Tags

All Tags » sql » performance   (RSS)
Showing page 1 of 3 (26 total posts)
  • SQL 2014 queries under a strobe light

    I just wrote a post about Live Query Statistics. Let me show you how this technology in SQL Server 2014 can be used for some amazingly cool (nerdy cool, at least) stuff. Behind the scenes, LQS uses a DMV called sys.dm_exec_query_profiles. When you run a query with SET STATISTICS PROFILE ON, the engine puts data into this DMV for every operator in ...
    Posted to Rob Farley (Weblog) by rob_farley on August 31, 2015
  • Live Query Statistics in SQL 2014, not just SQL 2016

    One of the coolest things in SQL Server 2016 is Live Query Statistics (LQS). But did you know that it’s available in SQL 2014? (Edit: Needs SP1) The thing is that we haven’t been able to view it effectively before now, before SQL Server Management Studio 2016 became available. LQS provides the ability to watch an execution plan while the query ...
    Posted to Rob Farley (Weblog) by rob_farley on August 31, 2015
  • Tuning slow spatial queries in SQL Server

    Even with the right indexes in place, spatial queries in SQL Server are often too slow – but they needn’t be. Two of the most commonly found patterns of query in the spatial world are when you’re looking for the nearest thing to where you are (which I’ve written about before), and when you’re looking for the points that are within a particular ...
    Posted to Rob Farley (Weblog) by rob_farley on April 28, 2015
  • Tuning Parallel Data Warehouse Queries

    Performance tuning in regular SQL Server can be addressed in a number of ways. This can involve looking at what’s going on with the disk configuration, the memory configuration, the wait stats, the parallelism settings, indexing, and so much more. But if you have a Parallel Data Warehouse (PDW) environment, then there are a lot of things that are ...
    Posted to Rob Farley (Weblog) by rob_farley on March 9, 2015
  • Why isn’t my filtered index being used?

    Quite often, people have filtered indexes but find they’re not being used as often as they’d like. I was reminded of this recently when I read a good post by Kendra Little from brentozar.com about filtered indexes. In it, Kendra talks about how the WHERE clause of a filtered index allows an IN clause, but not an OR clause (to quote someone from ...
    Posted to Rob Farley (Weblog) by rob_farley on February 22, 2015
  • Medians pre-SQL 2012

    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 ...
    Posted to Rob Farley (Weblog) by rob_farley on January 26, 2015
  • Minimising Data Movement in PDW Using Query Optimisation Techniques

    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 ...
    Posted to Rob Farley (Weblog) by rob_farley on December 4, 2014
  • SQL Spatial: Getting “nearest” calculations working properly

    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 ...
    Posted to Rob Farley (Weblog) by rob_farley on August 14, 2014
  • SSIS Lookup transformation in T-SQL

    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 ...
    Posted to Rob Farley (Weblog) by rob_farley on July 8, 2014
  • SQL 2014 does data the way developers want

    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 ...
    Posted to Rob Farley (Weblog) by rob_farley on June 9, 2014
1 2 3 Next >
Powered by Community Server (Commercial Edition), by Telligent Systems
  Privacy Statement