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From "dhruba borthakur (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HADOOP-5438) Merge FileSystem.create and FileSystem.append
Date Mon, 30 Mar 2009 17:48:51 GMT

    [ https://issues.apache.org/jira/browse/HADOOP-5438?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12693861#action_12693861
] 

dhruba borthakur commented on HADOOP-5438:
------------------------------------------

1. You have to bump out the versionID number in ClientProtocol.
2. Please leave the original public method signatures in FileSystem.java as they are (deprecate
them). This is to ensure that existing apps do not break. Then create a new create method
signature and make the old methods invoke the new create method internally.
3. And, of course, we would like a unit test that invokes the new create method with all supported
flags. One option would be to add a new method to TestFileCreation.java.

> Merge FileSystem.create and FileSystem.append
> ---------------------------------------------
>
>                 Key: HADOOP-5438
>                 URL: https://issues.apache.org/jira/browse/HADOOP-5438
>             Project: Hadoop Core
>          Issue Type: Improvement
>            Reporter: He Yongqiang
>         Attachments: Hadoop-5438-2009-03-30.patch
>
>
> Currently, when a user wants to modify a file, the user first calls exists() to know
if this file is already there. And then uses create() or append() according to whether the
file exists or not.
> the code looks like:
> {code}
> FSDataOutputStream out_1 = null;
> if (fs.exists(path_1))
>    out_1 = fs.append(path_1);
> else
>    out_1 = fs.create(path_1);
> {code}
> . On the performace side,It involes two RPCs. On the easy-of-use side, it is not very
convient in contrast to the traditional open interface.
> It will more complicate if there is a overwrite parameter specified. I donot know whether
there is a bug about 'overwrite' in 0.19, some times it takes a long time for overwrite creates
to reture. So i make the write file code with overwrite param works like:
> {code}
> boolean exists = fs.exists(name);
> if (overwrite) {
>     if (exists)
>        fs.delete(name, true);
>      this.out = fs.create(name, overwrite, bufferSize, replication,
> 				    blockSize, progress);
>      this.currentRowID = 0;
>  } else {
>    if (!exists)
> 	this.out = fs.create(name, overwrite, bufferSize,
> 					replication, blockSize, progress);
>    else
> 	this.out = fs.append(name, bufferSize, progress);
> {code}
> Some code statements there are really redundant and not needed, especialy with the delete().
But without deleting first, the overwrite takes a long time to reture.
> BTW, i will create another issue about the overwrite problem. If it is not a bug at all
or a duplicate, someone please close it.

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