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Colin Patrick McCabe commented on HDFS-8246: -------------------------------------------- How about having {{/.reserved/.blockIdToFiles/$ID}} map to a directory containing the hdfs files which have the given block ID? I think this would be a lot better than having a whole other set of APIs. Remember also that multiple snapshotted files can contain the same block ID. > Get HDFS file name based on block pool id and block id > ------------------------------------------------------ > > Key: HDFS-8246 > URL: https://issues.apache.org/jira/browse/HDFS-8246 > Project: Hadoop HDFS > Issue Type: New Feature > Components: HDFS, hdfs-client, namenode > Reporter: feng xu > Assignee: feng xu > Attachments: HDFS-8246.0.patch > > > This feature provides HDFS shell command and C/Java API to retrieve HDFS file > name based on block pool id and block id. > 1. The Java API in class DistributedFileSystem > public String getFileName(String poolId, long blockId) throws IOException > 2. The C API in hdfs.c > char* hdfsGetFileName(hdfsFS fs, const char* poolId, int64_t blockId) > 3. The HDFS shell command > hdfs dfs [generic options] -fn <poolId> <blockId> > This feature is useful if you have HDFS block file name in local file system > and want to find out the related HDFS file name in HDFS name space > (http://stackoverflow.com/questions/10881449/how-to-find-file-from-blockname-in-hdfs-hadoop). > Each HDFS block file name in local file system contains both block pool id > and block id, for sample HDFS block file name > /hdfs/1/hadoop/hdfs/data/current/BP-97622798-10.3.11.84-1428081035160/current/finalized/subdir0/subdir0/blk_1073741825, > the block pool id is BP-97622798-10.3.11.84-1428081035160 and the block id > is 1073741825. The block pool id is uniquely related to a HDFS name > node/name space, and the block id is uniquely related to a HDFS file within > a HDFS name node/name space, so the combination of block pool id and a block > id is uniquely related a HDFS file name. > The shell command and C/Java API do not map the block pool id to name node, > so it’s user’s responsibility to talk to the correct name node in federation > environment that has multiple name nodes. The block pool id is used by name > node to check if the user is talking with the correct name node. > The implementation is straightforward. The client request to get HDFS file > name reaches the new method String getFileName(String poolId, long blockId) > in FSNamesystem in name node through RPC, and the new method does the > followings, > (1) Validate the block pool id. > (2) Create Block based on the block id. > (3) Get BlockInfoContiguous from Block. > (4) Get BlockCollection from BlockInfoContiguous. > (5) Get file name from BlockCollection. -- This message was sent by Atlassian JIRA (v6.3.4#6332)