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From "ASF GitHub Bot (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (DRILL-4990) Use new HDFS API access instead of listStatus to check if users have permissions to access workspace.
Date Tue, 15 Nov 2016 18:01:03 GMT

    [ https://issues.apache.org/jira/browse/DRILL-4990?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15667810#comment-15667810

ASF GitHub Bot commented on DRILL-4990:

Github user sohami commented on a diff in the pull request:

    --- Diff: exec/java-exec/src/main/java/org/apache/drill/exec/store/dfs/WorkspaceSchemaFactory.java
    @@ -151,15 +152,11 @@ public WorkspaceSchemaFactory(
       public boolean accessible(final String userName) throws IOException {
         final FileSystem fs = ImpersonationUtil.createFileSystem(userName, fsConf);
         try {
    -      // We have to rely on the listStatus as a FileSystem can have complicated controls
such as regular unix style
    -      // permissions, Access Control Lists (ACLs) or Access Control Expressions (ACE).
Hadoop 2.7 version of FileSystem
    --- End diff --
    Also can we please replace the comments with why we are using "fs.access" api instead.
Will be good for future use.

> Use new HDFS API access instead of listStatus to check if users have permissions to access
> -----------------------------------------------------------------------------------------------------
>                 Key: DRILL-4990
>                 URL: https://issues.apache.org/jira/browse/DRILL-4990
>             Project: Apache Drill
>          Issue Type: Bug
>          Components: Query Planning & Optimization
>    Affects Versions: 1.8.0
>            Reporter: Padma Penumarthy
>            Assignee: Sorabh Hamirwasia
>             Fix For: 1.9.0
> For every query, we build the schema tree (runSQL->getPlan->getNewDefaultSchema->getRootSchema).
All workspaces in all storage plugins are checked and are added to the schema tree if they
are accessible by the user who initiated the query.  For file system plugin, listStatus API
is used to check if  the workspace is accessible or not (WorkspaceSchemaFactory.accessible)
by the user.  The idea seem to be if the user does not have access to file(s) in the workspace,
listStatus will generate an exception and we return false. But, listStatus (which lists all
the entries of a directory) is an expensive operation when there are large number of files
in the directory. A new API is added in Hadoop 2.6 called access (HDFS-6570) which provides
the ability to check if the user has permissions on a file/directory.  Use this new API instead
of listStatus. 

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