{"id":584,"date":"2011-04-06T06:37:00","date_gmt":"2011-04-06T06:37:00","guid":{"rendered":"\/blogs\/paul\/post\/Survey-results-Common-causes-of-performance-problems.aspx"},"modified":"2013-01-01T18:53:48","modified_gmt":"2013-01-02T02:53:48","slug":"survey-results-common-causes-of-performance-problems","status":"publish","type":"post","link":"https:\/\/www.sqlskills.com\/blogs\/paul\/survey-results-common-causes-of-performance-problems\/","title":{"rendered":"Survey results: Common causes of performance problems"},"content":{"rendered":"<p>\n<font face=\"verdana,geneva\" size=\"2\">A couple of week ago I kicked off a survey about common causes of performance problems &#8211; see <\/font><a href=\"https:\/\/www.sqlskills.com\/blogs\/paul\/survey-what-are-the-most-common-causes-of-performance-problems\/\"><font face=\"verdana,geneva\" size=\"2\">here<\/font><\/a><font face=\"verdana,geneva\" size=\"2\"> for the survey. <\/font>\n<\/p>\n<p>\n<font face=\"verdana,geneva\" size=\"2\">Firstly I asked what was the root cause for the most recent performance problems you looked at &#8211; here are the results: <\/font>\n<\/p>\n<p>\n<font face=\"verdana,geneva\" size=\"2\">&nbsp;<img decoding=\"async\" src=\"https:\/\/www.sqlskills.com\/blogs\/paul\/wp-content\/uploads\/2011\/4\/mostrecentperf.jpg\" alt=\"\" \/> <\/font>\n<\/p>\n<p>\n<font face=\"verdana,geneva\" size=\"2\">Secondly I asked what you think the overall most common cause of performance problems is &#8211; here are the results: <\/font>\n<\/p>\n<p>\n<font face=\"verdana,geneva\" size=\"2\">&nbsp;<img decoding=\"async\" src=\"https:\/\/www.sqlskills.com\/blogs\/paul\/wp-content\/uploads\/2011\/4\/mostcommonperf.jpg\" alt=\"\" \/><\/font>\n<\/p>\n<p>\n<font face=\"verdana,geneva\" size=\"2\">The results are not surprising, but it&#39;s good to have empirical confirmation from the community &#8211; T-SQL code and then poor indexing strategy are the top two in both surveys, accounting for roughly 50% of all performance issues.<\/font>\n<\/p>\n<p>\n<font face=\"verdana,geneva\" size=\"2\">No matter how powerful the hardware and how much memory or IOPS capacity you have, if you write crappy code that means SQL Server has to&nbsp;use really non-optimal query plans then&nbsp;performance is going to be poor. It&#39;s really quite a low proportion of the time that hardware (including the I\/O subsystem) is the root-cause of a performance problem &#8211; usually it&#39;s just a symptom of a deeper problem.<\/font>\n<\/p>\n<p>\n<font face=\"verdana,geneva\" size=\"2\">One of the most common causes of poorly-performing T-SQL code and indexing strategy is that developers don&#39;t write and test the code in an environment that simulates a true production environment and workload. What works for 2 connections with 100 rows in a table isn&#39;t necessarily going to work for 1000 concurrent connections and millions of rows in a table. Another cause is making code changes directly in production without testing their impact.<\/font>\n<\/p>\n<p>\n<font face=\"verdana,geneva\" size=\"2\">Nothing much else to say here as the theme has been hit on by many people in the past, but now we have some numbers.<\/font>\n<\/p>\n<p>\n<font face=\"verdana,geneva\" size=\"2\">Thanks to all those who responded!<\/font><\/p>\n","protected":false},"excerpt":{"rendered":"<p>A couple of week ago I kicked off a survey about common causes of performance problems &#8211; see here for the survey. Firstly I asked what was the root cause for the most recent performance problems you looked at &#8211; here are the results: &nbsp; Secondly I asked what you think the overall most common [&hellip;]<\/p>\n","protected":false},"author":5,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[66,73,91],"tags":[],"class_list":["post-584","post","type-post","status-publish","format-standard","hentry","category-performance-tuning","category-query-tuning","category-surveys"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v26.5 - https:\/\/yoast.com\/wordpress\/plugins\/seo\/ -->\n<title>Survey results: Common causes of performance problems - Paul S. 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