{"action":"created","issue":{"url":"https://api.github.com/repos/open-falcon/graph/issues/3","labels_url":"https://api.github.com/repos/open-falcon/graph/issues/3/labels{/name}","comments_url":"https://api.github.com/repos/open-falcon/graph/issues/3/comments","events_url":"https://api.github.com/repos/open-falcon/graph/issues/3/events","html_url":"https://github.com/open-falcon/graph/issues/3","id":81298644,"number":3,"title":"关于使用RRD进行存储的疑问","user":{"login":"wkshare","id":2918384,"avatar_url":"https://avatars.githubusercontent.com/u/2918384?v=3","gravatar_id":"","url":"https://api.github.com/users/wkshare","html_url":"https://github.com/wkshare","followers_url":"https://api.github.com/users/wkshare/followers","following_url":"https://api.github.com/users/wkshare/following{/other_user}","gists_url":"https://api.github.com/users/wkshare/gists{/gist_id}","starred_url":"https://api.github.com/users/wkshare/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/wkshare/subscriptions","organizations_url":"https://api.github.com/users/wkshare/orgs","repos_url":"https://api.github.com/users/wkshare/repos","events_url":"https://api.github.com/users/wkshare/events{/privacy}","received_events_url":"https://api.github.com/users/wkshare/received_events","type":"User","site_admin":false},"labels":[],"state":"open","locked":false,"assignee":null,"milestone":null,"comments":2,"created_at":"2015-05-27T06:14:00Z","updated_at":"2015-05-28T06:16:22Z","closed_at":null,"body":"“我们参考RRDtool的理念，在数据每次存入的时候，会自动进行采样、归档。在默认的归档策略，一分钟push一次的频率下，历史数据保存5年。同时为了不丢失信息量，数据归档的时候，会按照平均值采样、最大值采样、最小值采样存三份。用户在查询某个metric，在过去一年的历史数据时，Graph会选择最合适的采样频率，返回采样过后的数据，提高了数据查询速度。”\r\n\r\n对这段话，有几个疑问：\r\n1、数据每次存入，怎么理解？什么情况下会触发一次数据存储？一次的存入量，怎么衡量？\r\n2、一分钟push一次的频率下，历史数据保存5年。频率降低的话，是否可以存储更久的数据？\r\n3、对于较久远的历史数据，保存的数据点会不会减少？"},"comment":{"url":"https://api.github.com/repos/open-falcon/graph/issues/comments/106191819","html_url":"https://github.com/open-falcon/graph/issues/3#issuecomment-106191819","issue_url":"https://api.github.com/repos/open-falcon/graph/issues/3","id":106191819,"user":{"login":"laiwei","id":792850,"avatar_url":"https://avatars.githubusercontent.com/u/792850?v=3","gravatar_id":"","url":"https://api.github.com/users/laiwei","html_url":"https://github.com/laiwei","followers_url":"https://api.github.com/users/laiwei/followers","following_url":"https://api.github.com/users/laiwei/following{/other_user}","gists_url":"https://api.github.com/users/laiwei/gists{/gist_id}","starred_url":"https://api.github.com/users/laiwei/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/laiwei/subscriptions","organizations_url":"https://api.github.com/users/laiwei/orgs","repos_url":"https://api.github.com/users/laiwei/repos","events_url":"https://api.github.com/users/laiwei/events{/privacy}","received_events_url":"https://api.github.com/users/laiwei/received_events","type":"User","site_admin":false},"created_at":"2015-05-28T06:16:22Z","updated_at":"2015-05-28T06:16:22Z","body":"1. 每次存入，就是用户每个周期，push一次数据的时候。\r\n2. 历史数据的保存时间，可以调整，你也可以调整为10年，那么磁盘空间的使用会稍微增多。频率越低，在浪费相同磁盘空间的情况下，当然存的时间会更久。\r\n3. 是的，久远的数据，会被采样存储。"}}