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Arun C Murthy commented on HDFS-4949: ------------------------------------- [~andrew.wang] overall it's looks great, some more questions: # I'm not sure you want to automatically add new files in a directory to the cache, it seems a higher-level system (Hive, Impala, HCat) are in better position. Not doing this automatically simplifies cache mgmt, quota mgmt etc. # Can you please provide details on the read apis? For the Hive/MR/Pig use case I'd like to see a new open(Path, offset, length) which returns an indicator for whether the block is cached or not. This, for e.g., would be used by the RecordReader to read the split. > Centralized cache management in HDFS > ------------------------------------ > > Key: HDFS-4949 > URL: https://issues.apache.org/jira/browse/HDFS-4949 > Project: Hadoop HDFS > Issue Type: New Feature > Components: datanode, namenode > Affects Versions: 3.0.0, 2.3.0 > Reporter: Andrew Wang > Assignee: Andrew Wang > Attachments: caching-design-doc-2013-07-02.pdf, > caching-design-doc-2013-08-09.pdf > > > HDFS currently has no support for managing or exposing in-memory caches at > datanodes. This makes it harder for higher level application frameworks like > Hive, Pig, and Impala to effectively use cluster memory, because they cannot > explicitly cache important datasets or place their tasks for memory locality. -- This message is automatically generated by JIRA. If you think it was sent incorrectly, please contact your JIRA administrators For more information on JIRA, see: http://www.atlassian.com/software/jira