[ https://issues.apache.org/jira/browse/HIVE-21040?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16724383#comment-16724383 ]
Prasanth Jayachandran commented on HIVE-21040: ---------------------------------------------- looks good otherwise. > msck does unnecessary file listing at last level of directory tree > ------------------------------------------------------------------ > > Key: HIVE-21040 > URL: https://issues.apache.org/jira/browse/HIVE-21040 > Project: Hive > Issue Type: Improvement > Reporter: Vihang Karajgaonkar > Assignee: Vihang Karajgaonkar > Priority: Major > Attachments: HIVE-21040.01.patch > > > Here is the code snippet which is run by {{msck}} to list directories > {noformat} > final Path currentPath = pd.p; > final int currentDepth = pd.depth; > FileStatus[] fileStatuses = fs.listStatus(currentPath, > FileUtils.HIDDEN_FILES_PATH_FILTER); > // found no files under a sub-directory under table base path; it is > possible that the table > // is empty and hence there are no partition sub-directories created > under base path > if (fileStatuses.length == 0 && currentDepth > 0 && currentDepth < > partColNames.size()) { > // since maxDepth is not yet reached, we are missing partition > // columns in currentPath > logOrThrowExceptionWithMsg( > "MSCK is missing partition columns under " + > currentPath.toString()); > } else { > // found files under currentPath add them to the queue if it is a > directory > for (FileStatus fileStatus : fileStatuses) { > if (!fileStatus.isDirectory() && currentDepth < > partColNames.size()) { > // found a file at depth which is less than number of partition > keys > logOrThrowExceptionWithMsg( > "MSCK finds a file rather than a directory when it searches > for " > + fileStatus.getPath().toString()); > } else if (fileStatus.isDirectory() && currentDepth < > partColNames.size()) { > // found a sub-directory at a depth less than number of partition > keys > // validate if the partition directory name matches with the > corresponding > // partition colName at currentDepth > Path nextPath = fileStatus.getPath(); > String[] parts = nextPath.getName().split("="); > if (parts.length != 2) { > logOrThrowExceptionWithMsg("Invalid partition name " + > nextPath); > } else if > (!parts[0].equalsIgnoreCase(partColNames.get(currentDepth))) { > logOrThrowExceptionWithMsg( > "Unexpected partition key " + parts[0] + " found at " + > nextPath); > } else { > // add sub-directory to the work queue if maxDepth is not yet > reached > pendingPaths.add(new PathDepthInfo(nextPath, currentDepth + 1)); > } > } > } > if (currentDepth == partColNames.size()) { > return currentPath; > } > } > {noformat} > You can see that when the {{currentDepth}} at the {{maxDepth}} it still does > a unnecessary listing of the files. We can improve this call by checking the > currentDepth and bailing out early. > This can improve the performance of msck command significantly especially > when there are lot of files in each partitions on remote filesystems like S3 > or ADLS -- This message was sent by Atlassian JIRA (v7.6.3#76005)