{"action":"created","issue":{"url":"https://api.github.com/repos/elastic/elasticsearch/issues/18209","repository_url":"https://api.github.com/repos/elastic/elasticsearch","labels_url":"https://api.github.com/repos/elastic/elasticsearch/issues/18209/labels{/name}","comments_url":"https://api.github.com/repos/elastic/elasticsearch/issues/18209/comments","events_url":"https://api.github.com/repos/elastic/elasticsearch/issues/18209/events","html_url":"https://github.com/elastic/elasticsearch/issues/18209","id":153777293,"number":18209,"title":"Auto-generated ids should put the mac address before the timestamp","user":{"login":"jpountz","id":299848,"avatar_url":"https://avatars.githubusercontent.com/u/299848?v=3","gravatar_id":"","url":"https://api.github.com/users/jpountz","html_url":"https://github.com/jpountz","followers_url":"https://api.github.com/users/jpountz/followers","following_url":"https://api.github.com/users/jpountz/following{/other_user}","gists_url":"https://api.github.com/users/jpountz/gists{/gist_id}","starred_url":"https://api.github.com/users/jpountz/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/jpountz/subscriptions","organizations_url":"https://api.github.com/users/jpountz/orgs","repos_url":"https://api.github.com/users/jpountz/repos","events_url":"https://api.github.com/users/jpountz/events{/privacy}","received_events_url":"https://api.github.com/users/jpountz/received_events","type":"User","site_admin":false},"labels":[{"url":"https://api.github.com/repos/elastic/elasticsearch/labels/:Internal","name":":Internal","color":"009800"},{"url":"https://api.github.com/repos/elastic/elasticsearch/labels/enhancement","name":"enhancement","color":"4a4ea8"}],"state":"open","locked":false,"assignee":{"login":"mikemccand","id":796508,"avatar_url":"https://avatars.githubusercontent.com/u/796508?v=3","gravatar_id":"","url":"https://api.github.com/users/mikemccand","html_url":"https://github.com/mikemccand","followers_url":"https://api.github.com/users/mikemccand/followers","following_url":"https://api.github.com/users/mikemccand/following{/other_user}","gists_url":"https://api.github.com/users/mikemccand/gists{/gist_id}","starred_url":"https://api.github.com/users/mikemccand/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/mikemccand/subscriptions","organizations_url":"https://api.github.com/users/mikemccand/orgs","repos_url":"https://api.github.com/users/mikemccand/repos","events_url":"https://api.github.com/users/mikemccand/events{/privacy}","received_events_url":"https://api.github.com/users/mikemccand/received_events","type":"User","site_admin":false},"milestone":null,"comments":8,"created_at":"2016-05-09T13:34:14Z","updated_at":"2016-05-10T15:55:51Z","closed_at":null,"body":"Given that the terms dictionary has the structure of a trie, it compresses better when there are shared prefixes. By putting the mac address before the timestamp in our auto-generated ids, the `_uid` field would compress better. I suspect it will also slightly help for stored fields since there will be longer sequences of bytes that are shared across values (the mac address followed by the first bytes of the timestamp)."},"comment":{"url":"https://api.github.com/repos/elastic/elasticsearch/issues/comments/218203699","html_url":"https://github.com/elastic/elasticsearch/issues/18209#issuecomment-218203699","issue_url":"https://api.github.com/repos/elastic/elasticsearch/issues/18209","id":218203699,"user":{"login":"polyfractal","id":1224228,"avatar_url":"https://avatars.githubusercontent.com/u/1224228?v=3","gravatar_id":"","url":"https://api.github.com/users/polyfractal","html_url":"https://github.com/polyfractal","followers_url":"https://api.github.com/users/polyfractal/followers","following_url":"https://api.github.com/users/polyfractal/following{/other_user}","gists_url":"https://api.github.com/users/polyfractal/gists{/gist_id}","starred_url":"https://api.github.com/users/polyfractal/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/polyfractal/subscriptions","organizations_url":"https://api.github.com/users/polyfractal/orgs","repos_url":"https://api.github.com/users/polyfractal/repos","events_url":"https://api.github.com/users/polyfractal/events{/privacy}","received_events_url":"https://api.github.com/users/polyfractal/received_events","type":"User","site_admin":false},"created_at":"2016-05-10T15:55:51Z","updated_at":"2016-05-10T15:55:51Z","body":"Obligatory stats nerd interjection: the difference in the two indexing speeds is not statistically significant.  Two-tailed, unpaired, unequal variance t-test gives a **p = 0.2889**, which is greater than the standard 0.05 threshold.\r\n\r\n![screen shot 2016-05-10 at 11 38 16 am](https://cloud.githubusercontent.com/assets/1224228/15152709/43070ec8-16a4-11e6-8bbb-5a2c1c7352f3.png)\r\n\r\nThe change in index size is statistically significant though:  **p = 5.773 x 10<sup>-09</sup>**\r\n\r\n![screen shot 2016-05-10 at 11 44 54 am](https://cloud.githubusercontent.com/assets/1224228/15152875/fbfc3048-16a4-11e6-9c31-4f4262963940.png)\r\n\r\nObviously this is on a small sample size, so the indexing speed significance may change if more samples are added (a true mean shift, or an increase in variance, etc).  But from the current data I don't think we can draw any conclusions.\r\n"}}