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https://issues.apache.org/jira/browse/HADOOP-16673?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16962267#comment-16962267
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Steve Loughran edited comment on HADOOP-16673 at 10/29/19 5:52 PM:
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This wouldn't work. The path filtering you have described will only work
efficiently if you are actually doing a tree walk. For S3 we are issuing LIST
path/ commands and getting pages of results back. There is no way we could do
this filtering except by doing exactly what you are trying to do yourself: List
everything then discard the stuff that is not needed. It won't be any more
efficient it will only set unrealistic expectations on performance.
Have a look at {{org.apache.hadoop.fs.s3a.Listing.ProvidedFileStatusIterator}}
to see what todo. You just need to write an iterator which wraps the current
one and does the filtering there, which you can then iterate over.
Closing as a WONTFIX. Sorry
I'll look at the Hive problem.
+[~gabor.bota]
was (Author: [email protected]):
This wouldn't work. The path filtering you have described Will only work
efficiently if you are actually doing a tree walk. For S3 we are issuing LIST
path/ commands and getting pages of results back. There is no way we could do
this filtering except by doing exactly what you are trying to do yourself: List
everything then discard the stuff that is not needed. It won't be any more
efficient it will only set unrealistic expectations on performance.
Have a look at {{org.apache.hadoop.fs.s3a.Listing.ProvidedFileStatusIterator}}
to see what todo. You just need to write an iterator which wraps the current
one and does the filtering there, which you can then iterate over.
Closing as a WONTFIX. Sorry
I'll look at the Hive problem.
+[~gabor.bota]
> Add filter parameter to FileSystem>>listFiles
> ---------------------------------------------
>
> Key: HADOOP-16673
> URL: https://issues.apache.org/jira/browse/HADOOP-16673
> Project: Hadoop Common
> Issue Type: Improvement
> Components: fs, fs/s3
> Affects Versions: 3.2.2
> Reporter: Attila Magyar
> Priority: Major
>
> Currently getting recursively a filtered list of files in a directory is
> clumsy because filtering should happen afterwards on the result list.
> Imagine we want to list all non hidden files recursively.
> The non hidden files filter is defined as:
> {code:java}
> !name.startsWith("_") && !name.startsWith(".") {code}
>
> Then we can do:
>
> {code:java}
> RemoteIterator<LocatedFileStatus> remoteIterator = fs.listFiles(path,
> /*recursive*/true);
> while (remoteIterator.hasNext()) {
> LocatedFileStatus each = remoteIterator.next();
> if (filter applies to all of the path elements in each) {
> result.add(each);
> }
> }
>
> {code}
>
> For example each of these paths should be skipped:
> * /.a/b/c
> * /a/.b/c
> * /a/b/.c/
> It would be lot better to have a filter parameter on listFiles. This is
> needed to solve HIVE-22411 effectively.
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