{"action":"created","issue":{"url":"https://api.github.com/repos/chocolate-factory/realmysql-study/issues/1","repository_url":"https://api.github.com/repos/chocolate-factory/realmysql-study","labels_url":"https://api.github.com/repos/chocolate-factory/realmysql-study/issues/1/labels{/name}","comments_url":"https://api.github.com/repos/chocolate-factory/realmysql-study/issues/1/comments","events_url":"https://api.github.com/repos/chocolate-factory/realmysql-study/issues/1/events","html_url":"https://github.com/chocolate-factory/realmysql-study/issues/1","id":320482415,"node_id":"MDU6SXNzdWUzMjA0ODI0MTU=","number":1,"title":"[7-1] group_concat 사용시 설정된 메모리 초과하게 되면 disk에 쓰는가?","user":{"login":"JungleKim","id":7233778,"node_id":"MDQ6VXNlcjcyMzM3Nzg=","avatar_url":"https://avatars0.githubusercontent.com/u/7233778?v=4","gravatar_id":"","url":"https://api.github.com/users/JungleKim","html_url":"https://github.com/JungleKim","followers_url":"https://api.github.com/users/JungleKim/followers","following_url":"https://api.github.com/users/JungleKim/following{/other_user}","gists_url":"https://api.github.com/users/JungleKim/gists{/gist_id}","starred_url":"https://api.github.com/users/JungleKim/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/JungleKim/subscriptions","organizations_url":"https://api.github.com/users/JungleKim/orgs","repos_url":"https://api.github.com/users/JungleKim/repos","events_url":"https://api.github.com/users/JungleKim/events{/privacy}","received_events_url":"https://api.github.com/users/JungleKim/received_events","type":"User","site_admin":false},"labels":[{"id":923379974,"node_id":"MDU6TGFiZWw5MjMzNzk5NzQ=","url":"https://api.github.com/repos/chocolate-factory/realmysql-study/labels/%EC%BD%94%EB%A9%98%ED%8A%B8","name":"코멘트","color":"36769b","default":false}],"state":"open","locked":false,"assignee":{"login":"yangroro","id":4294015,"node_id":"MDQ6VXNlcjQyOTQwMTU=","avatar_url":"https://avatars0.githubusercontent.com/u/4294015?v=4","gravatar_id":"","url":"https://api.github.com/users/yangroro","html_url":"https://github.com/yangroro","followers_url":"https://api.github.com/users/yangroro/followers","following_url":"https://api.github.com/users/yangroro/following{/other_user}","gists_url":"https://api.github.com/users/yangroro/gists{/gist_id}","starred_url":"https://api.github.com/users/yangroro/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/yangroro/subscriptions","organizations_url":"https://api.github.com/users/yangroro/orgs","repos_url":"https://api.github.com/users/yangroro/repos","events_url":"https://api.github.com/users/yangroro/events{/privacy}","received_events_url":"https://api.github.com/users/yangroro/received_events","type":"User","site_admin":false},"assignees":[{"login":"yangroro","id":4294015,"node_id":"MDQ6VXNlcjQyOTQwMTU=","avatar_url":"https://avatars0.githubusercontent.com/u/4294015?v=4","gravatar_id":"","url":"https://api.github.com/users/yangroro","html_url":"https://github.com/yangroro","followers_url":"https://api.github.com/users/yangroro/followers","following_url":"https://api.github.com/users/yangroro/following{/other_user}","gists_url":"https://api.github.com/users/yangroro/gists{/gist_id}","starred_url":"https://api.github.com/users/yangroro/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/yangroro/subscriptions","organizations_url":"https://api.github.com/users/yangroro/orgs","repos_url":"https://api.github.com/users/yangroro/repos","events_url":"https://api.github.com/users/yangroro/events{/privacy}","received_events_url":"https://api.github.com/users/yangroro/received_events","type":"User","site_admin":false}],"milestone":null,"comments":0,"created_at":"2018-05-05T05:50:43Z","updated_at":"2018-08-04T01:10:16Z","closed_at":null,"author_association":"MEMBER","body":"메모리를 초과하면 Warning이 나온다고 하는데, Disk에 쓰면서 처리한 후 Warning을 보여주는 건지 확인."},"comment":{"url":"https://api.github.com/repos/chocolate-factory/realmysql-study/issues/comments/410411096","html_url":"https://github.com/chocolate-factory/realmysql-study/issues/1#issuecomment-410411096","issue_url":"https://api.github.com/repos/chocolate-factory/realmysql-study/issues/1","id":410411096,"node_id":"MDEyOklzc3VlQ29tbWVudDQxMDQxMTA5Ng==","user":{"login":"TaeGuNi","id":3734068,"node_id":"MDQ6VXNlcjM3MzQwNjg=","avatar_url":"https://avatars0.githubusercontent.com/u/3734068?v=4","gravatar_id":"","url":"https://api.github.com/users/TaeGuNi","html_url":"https://github.com/TaeGuNi","followers_url":"https://api.github.com/users/TaeGuNi/followers","following_url":"https://api.github.com/users/TaeGuNi/following{/other_user}","gists_url":"https://api.github.com/users/TaeGuNi/gists{/gist_id}","starred_url":"https://api.github.com/users/TaeGuNi/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/TaeGuNi/subscriptions","organizations_url":"https://api.github.com/users/TaeGuNi/orgs","repos_url":"https://api.github.com/users/TaeGuNi/repos","events_url":"https://api.github.com/users/TaeGuNi/events{/privacy}","received_events_url":"https://api.github.com/users/TaeGuNi/received_events","type":"User","site_admin":false},"created_at":"2018-08-04T01:10:16Z","updated_at":"2018-08-04T01:10:16Z","author_association":"NONE","body":"https://dev.mysql.com/doc/refman/5.7/en/group-by-functions.html#function_group-concat\r\n\r\ngroup_concat은 단순히 문자열 함수에 불과 합니다. 합쳐진 문자열 길이에 제한을 변수로 조절할 수 있을 뿐입니다.\r\n이렇게 가공된 결과 셋은 출력전 임시테이블에 저장하게 되는데, 이 때, 시스템 변수로 할당된 메모리에 용량이 넘어가면 디스크에서 작성이 되게 됩니다. 아래 시스템 변수의 설명을 확인해보면 도움이 될 수 있습니다.\r\ngroup by, order by, inline view 구문등 많은 쿼리에서 실제로 데이터 가공을 위해서 쿼리 수행시 tmp_table을  작성하며, 결과셋의 크기가 tmp_table_size 또는 max_heap_table_size의 설정값을 넘어가면, 디스크에 작성하게 됩니다.\r\n\r\n생각 해볼 사항으로는 그럼 tmp_table_size의 크기를 크게 하면 되지 않을까?에 대한 고민을 해보면 좋을 것 같습니다.\r\n\r\nhttps://dev.mysql.com/doc/refman/5.7/en/server-system-variables.html#sysvar_max_heap_table_size\r\n\r\nhttps://dev.mysql.com/doc/refman/5.7/en/server-system-variables.html#sysvar_tmp_table_size"}}
{"actor":{"display_login":"TaeGuNi"}}