[jira] Updated: (HADOOP-1296) Improve interface to FileSystem.getFileCacheHints

["dhruba borthakur (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/HADOOP-1296?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

dhruba borthakur updated HADOOP-1296:
-------------------------------------

    Fix Version/s: 0.15.0

> Improve interface to FileSystem.getFileCacheHints
> -------------------------------------------------
>
>                 Key: HADOOP-1296
>                 URL: https://issues.apache.org/jira/browse/HADOOP-1296
>             Project: Hadoop
>          Issue Type: Improvement
>          Components: fs
>            Reporter: Owen O'Malley
>            Assignee: dhruba borthakur
>             Fix For: 0.15.0
>
>
> The FileSystem interface provides a very limited interface for finding the location of the data. The current method looks like:
> String[][] getFileCacheHints(Path file, long start, long len) throws IOException
> which returns a list of "block info" where the block info consists of a list host names. Because the hints don't include the information about where the block boundaries are, map/reduce is required to call the name node for each split. I'd propose that we fix the naming a bit and make it:
> public class BlockInfo extends Writable {
>   public long getStart();
>   public String[] getHosts();
> }
> BlockInfo[] getFileHints(Path file, long start, long len) throws IOException;
> So that map/reduce can query about the entire file and get the locations in a single call.

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