{"id":19,"date":"2007-08-20T19:46:17","date_gmt":"2007-08-20T17:46:17","guid":{"rendered":"https:\/\/www.sqlinthewild.co.za\/?p=19"},"modified":"2007-08-20T19:46:17","modified_gmt":"2007-08-20T17:46:17","slug":"reading-execution-plans","status":"publish","type":"post","link":"https:\/\/www.sqlinthewild.co.za\/index.php\/2007\/08\/20\/reading-execution-plans\/","title":{"rendered":"Reading Execution plans"},"content":{"rendered":"

One of the more common questions I get from colleagues is on how to read the execution plan that SQL produces. At first I found it quite a hard question to answer as no one really taught me how to read them. When I started with performance tuning I got a bit thrown in the deep end.<\/p>\n

This is going to be the first in a series, maybe short, maybe long, on reading SQL’s execution plans. I’m going to go into the overall structure of a plan; the differences between the actual and the estimated plans, and how to obtain both; and some of the more common query operators and how they affect query performance.<\/p>\n

If you have any specific questions that you’d like answering regarding execution plans, please post a comment here. Otherwise I’m going to ramble on a bit touching on things that I feel are important and relevant and maybe missing things that you would like to know.<\/p>\n

Current articles in this series, in order of writing, are<\/p>\n

    \n
  1. Structure of an execution plan<\/a><\/li>\n
  2. Execution plans, estimated vs actual<\/a><\/li>\n
  3. Execution plans from Profiler<\/a><\/li>\n
  4. A basic execution plan<\/a><\/li>\n
  5. Execution plan operations – scans and seeks<\/a><\/li>\n
  6. Execution plan operations – joins<\/a><\/li>\n
  7. Execution plan operations – aggregate<\/a><\/li>\n
  8. Execution plan operations – misc<\/a><\/li>\n
  9. Execution plans – important properties<\/a><\/li>\n
  10. Execution plan – more properties<\/a><\/li>\n
  11. An example execution plan<\/a><\/li>\n<\/ol>\n

    There is more to come.<\/p>\n","protected":false},"excerpt":{"rendered":"

    One of the more common questions I get from colleagues is on how to read the execution plan that SQL produces. At first I found it quite a hard question to answer as no one really taught me how to… (Read more)<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"jetpack_post_was_ever_published":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":false,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2}},"categories":[23,15],"tags":[],"class_list":["post-19","post","type-post","status-publish","format-standard","hentry","category-execution-plans","category-sql-server"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"","jetpack_shortlink":"https:\/\/wp.me\/p7h6n-j","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/www.sqlinthewild.co.za\/index.php\/wp-json\/wp\/v2\/posts\/19","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.sqlinthewild.co.za\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.sqlinthewild.co.za\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.sqlinthewild.co.za\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.sqlinthewild.co.za\/index.php\/wp-json\/wp\/v2\/comments?post=19"}],"version-history":[{"count":0,"href":"https:\/\/www.sqlinthewild.co.za\/index.php\/wp-json\/wp\/v2\/posts\/19\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.sqlinthewild.co.za\/index.php\/wp-json\/wp\/v2\/media?parent=19"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.sqlinthewild.co.za\/index.php\/wp-json\/wp\/v2\/categories?post=19"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.sqlinthewild.co.za\/index.php\/wp-json\/wp\/v2\/tags?post=19"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}