{"action":"opened","issue":{"url":"https://api.github.com/repos/metabase/metabase/issues/2175","repository_url":"https://api.github.com/repos/metabase/metabase","labels_url":"https://api.github.com/repos/metabase/metabase/issues/2175/labels{/name}","comments_url":"https://api.github.com/repos/metabase/metabase/issues/2175/comments","events_url":"https://api.github.com/repos/metabase/metabase/issues/2175/events","html_url":"https://github.com/metabase/metabase/issues/2175","id":141439438,"number":2175,"title":"MySQL should use sample standard deviation","user":{"login":"camsaul","id":1455846,"avatar_url":"https://avatars.githubusercontent.com/u/1455846?v=3","gravatar_id":"","url":"https://api.github.com/users/camsaul","html_url":"https://github.com/camsaul","followers_url":"https://api.github.com/users/camsaul/followers","following_url":"https://api.github.com/users/camsaul/following{/other_user}","gists_url":"https://api.github.com/users/camsaul/gists{/gist_id}","starred_url":"https://api.github.com/users/camsaul/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/camsaul/subscriptions","organizations_url":"https://api.github.com/users/camsaul/orgs","repos_url":"https://api.github.com/users/camsaul/repos","events_url":"https://api.github.com/users/camsaul/events{/privacy}","received_events_url":"https://api.github.com/users/camsaul/received_events","type":"User","site_admin":false},"labels":[{"url":"https://api.github.com/repos/metabase/metabase/labels/Correctness","name":"Correctness","color":"e11d21"},{"url":"https://api.github.com/repos/metabase/metabase/labels/Database/MySQL","name":"Database/MySQL","color":"782E53"},{"url":"https://api.github.com/repos/metabase/metabase/labels/Query%20Processor","name":"Query Processor","color":"68BEFC"}],"state":"open","locked":false,"assignee":null,"milestone":null,"comments":0,"created_at":"2016-03-17T00:15:40Z","updated_at":"2016-03-17T00:15:40Z","closed_at":null,"body":"MySQL's `stddev()`is an alias of `stddev_pop()`, i.e. a population standard deviation. All of our other databases that support standard deviations do sample ones, which is available in MySQL as `stddev_samp()`. We should use this function instead to bring MySQL's behavior in line with our other databases.\r\n\r\nThis would probably let us eliminate some of the special-casing in the unit tests around sample deviation aggregations where MySQL returns slightly different results from the other DBs."}}