{"action":"created","issue":{"url":"https://api.github.com/repos/facebook/rocksdb/issues/1495","repository_url":"https://api.github.com/repos/facebook/rocksdb","labels_url":"https://api.github.com/repos/facebook/rocksdb/issues/1495/labels{/name}","comments_url":"https://api.github.com/repos/facebook/rocksdb/issues/1495/comments","events_url":"https://api.github.com/repos/facebook/rocksdb/issues/1495/events","html_url":"https://github.com/facebook/rocksdb/pull/1495","id":188599313,"number":1495,"title":"delete transactions recovered from stale logs","user":{"login":"reidHoruff","id":950932,"avatar_url":"https://avatars.githubusercontent.com/u/950932?v=3","gravatar_id":"","url":"https://api.github.com/users/reidHoruff","html_url":"https://github.com/reidHoruff","followers_url":"https://api.github.com/users/reidHoruff/followers","following_url":"https://api.github.com/users/reidHoruff/following{/other_user}","gists_url":"https://api.github.com/users/reidHoruff/gists{/gist_id}","starred_url":"https://api.github.com/users/reidHoruff/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/reidHoruff/subscriptions","organizations_url":"https://api.github.com/users/reidHoruff/orgs","repos_url":"https://api.github.com/users/reidHoruff/repos","events_url":"https://api.github.com/users/reidHoruff/events{/privacy}","received_events_url":"https://api.github.com/users/reidHoruff/received_events","type":"User","site_admin":false},"labels":[],"state":"open","locked":false,"assignee":null,"assignees":[],"milestone":null,"comments":0,"created_at":"2016-11-10T19:40:05Z","updated_at":"2016-11-10T19:43:20Z","closed_at":null,"pull_request":{"url":"https://api.github.com/repos/facebook/rocksdb/pulls/1495","html_url":"https://github.com/facebook/rocksdb/pull/1495","diff_url":"https://github.com/facebook/rocksdb/pull/1495.diff","patch_url":"https://github.com/facebook/rocksdb/pull/1495.patch"},"body":"It may be possible for a scenario to arise where stale WAL logs are deleted out of order. This has the potential to create a gap in the logs read from on recovery.\r\n\r\nconsider scenario:\r\ntransaction is prepared in log A.\r\ntransaction is committed in log B.\r\ncurrent log is C, A and B are release.\r\nlog B is deleted.\r\nrecovery happens.\r\n\r\nIn this scenario the transaction would be recovered as if is had not been committed because we cannot have reliable knowledge that only log C was needed for recovery. It IS possible to detect that log B was missing and that all logs before must have been released in the previous incarnation. We use this knowledge to clear all recovered transactions when we detect a gap."},"comment":{"url":"https://api.github.com/repos/facebook/rocksdb/issues/comments/259787679","html_url":"https://github.com/facebook/rocksdb/pull/1495#issuecomment-259787679","issue_url":"https://api.github.com/repos/facebook/rocksdb/issues/1495","id":259787679,"user":{"login":"facebook-github-bot","id":6422482,"avatar_url":"https://avatars.githubusercontent.com/u/6422482?v=3","gravatar_id":"","url":"https://api.github.com/users/facebook-github-bot","html_url":"https://github.com/facebook-github-bot","followers_url":"https://api.github.com/users/facebook-github-bot/followers","following_url":"https://api.github.com/users/facebook-github-bot/following{/other_user}","gists_url":"https://api.github.com/users/facebook-github-bot/gists{/gist_id}","starred_url":"https://api.github.com/users/facebook-github-bot/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/facebook-github-bot/subscriptions","organizations_url":"https://api.github.com/users/facebook-github-bot/orgs","repos_url":"https://api.github.com/users/facebook-github-bot/repos","events_url":"https://api.github.com/users/facebook-github-bot/events{/privacy}","received_events_url":"https://api.github.com/users/facebook-github-bot/received_events","type":"User","site_admin":false},"created_at":"2016-11-10T19:43:20Z","updated_at":"2016-11-10T19:43:20Z","body":"@reidHoruff has imported this pull request.  If you are a Facebook employee, you can view this diff [on Phabricator](https://phabricator.intern.facebook.com/D4161648)."}}
{"actor":{"display_login":"facebook-github-bot"}}