{"action":"created","issue":{"url":"https://api.github.com/repos/apache/flink/issues/5465","repository_url":"https://api.github.com/repos/apache/flink","labels_url":"https://api.github.com/repos/apache/flink/issues/5465/labels{/name}","comments_url":"https://api.github.com/repos/apache/flink/issues/5465/comments","events_url":"https://api.github.com/repos/apache/flink/issues/5465/events","html_url":"https://github.com/apache/flink/pull/5465","id":296401592,"number":5465,"title":"[FLINK-8639][State Backends]Fix always need to seek multiple times when iterator RocksDBMapState","user":{"login":"sihuazhou","id":7480427,"avatar_url":"https://avatars2.githubusercontent.com/u/7480427?v=4","gravatar_id":"","url":"https://api.github.com/users/sihuazhou","html_url":"https://github.com/sihuazhou","followers_url":"https://api.github.com/users/sihuazhou/followers","following_url":"https://api.github.com/users/sihuazhou/following{/other_user}","gists_url":"https://api.github.com/users/sihuazhou/gists{/gist_id}","starred_url":"https://api.github.com/users/sihuazhou/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/sihuazhou/subscriptions","organizations_url":"https://api.github.com/users/sihuazhou/orgs","repos_url":"https://api.github.com/users/sihuazhou/repos","events_url":"https://api.github.com/users/sihuazhou/events{/privacy}","received_events_url":"https://api.github.com/users/sihuazhou/received_events","type":"User","site_admin":false},"labels":[],"state":"open","locked":false,"assignee":null,"assignees":[],"milestone":null,"comments":6,"created_at":"2018-02-12T14:51:25Z","updated_at":"2018-02-21T13:21:30Z","closed_at":null,"author_association":"CONTRIBUTOR","pull_request":{"url":"https://api.github.com/repos/apache/flink/pulls/5465","html_url":"https://github.com/apache/flink/pull/5465","diff_url":"https://github.com/apache/flink/pull/5465.diff","patch_url":"https://github.com/apache/flink/pull/5465.patch"},"body":"## What is the purpose of the change\r\n\r\nThis PR addressed issue [FLINK-8639](https://issues.apache.org/jira/browse/FLINK-8639). Currently, almost every time we want to iterator a RocksDBMapState we need to do seek at least 2 times (Seek is a poor performance action for rocksdb cause it can't use the bloomfilter). This is because `RocksDBMapIterator` use a `cacheEntries` to cache the seek values every time and the `cacheEntries`'s init size is 1.\r\n\r\n## Brief change log\r\n\r\n\r\n- Change CACHE_SIZE_BASE from 1 to 32.\r\n- Compare in reverse order in function underSameKey().\r\n\r\n## Verifying this change\r\n\r\nThis change is already covered by existing tests.\r\n\r\n## Does this pull request potentially affect one of the following parts:\r\n\r\n  - Dependencies (does it add or upgrade a dependency): (no)\r\n  - The public API, i.e., is any changed class annotated with `@Public(Evolving)`: (no)\r\n  - The serializers: (no)\r\n  - The runtime per-record code paths (performance sensitive): (no)\r\n  - Anything that affects deployment or recovery: JobManager (and its components), Checkpointing, Yarn/Mesos, ZooKeeper: (no)\r\n  - The S3 file system connector: (no)\r\n\r\n## Documentation\r\n\r\n  - Does this pull request introduce a new feature? (no)\r\n"},"comment":{"url":"https://api.github.com/repos/apache/flink/issues/comments/367323739","html_url":"https://github.com/apache/flink/pull/5465#issuecomment-367323739","issue_url":"https://api.github.com/repos/apache/flink/issues/5465","id":367323739,"user":{"login":"sihuazhou","id":7480427,"avatar_url":"https://avatars2.githubusercontent.com/u/7480427?v=4","gravatar_id":"","url":"https://api.github.com/users/sihuazhou","html_url":"https://github.com/sihuazhou","followers_url":"https://api.github.com/users/sihuazhou/followers","following_url":"https://api.github.com/users/sihuazhou/following{/other_user}","gists_url":"https://api.github.com/users/sihuazhou/gists{/gist_id}","starred_url":"https://api.github.com/users/sihuazhou/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/sihuazhou/subscriptions","organizations_url":"https://api.github.com/users/sihuazhou/orgs","repos_url":"https://api.github.com/users/sihuazhou/repos","events_url":"https://api.github.com/users/sihuazhou/events{/privacy}","received_events_url":"https://api.github.com/users/sihuazhou/received_events","type":"User","site_admin":false},"created_at":"2018-02-21T13:21:30Z","updated_at":"2018-02-21T13:21:30Z","author_association":"CONTRIBUTOR","body":"Aha, for now I would like to leave it to 128 ...  Even I can't find a best value, but this value is not a bad value and is also a safety value.. If I found any another value that is better than it (on production), I will feed back to community at that time."}}
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