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Date: Mon, 30 Mar 2009 22:43:50 -0700 (PDT)
From: "He Yongqiang (JIRA)" <jira@apache.org>
To: core-dev@hadoop.apache.org
Subject: [jira] Updated: (HADOOP-5438) Merge FileSystem.create and
 FileSystem.append
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     [ https://issues.apache.org/jira/browse/HADOOP-5438?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

He Yongqiang updated HADOOP-5438:
---------------------------------

    Attachment: Hadoop-5438-2009-03-31.patch

1) attach an update version according to dhruba's suggestions. Thanks, dhruba.
2) create HADOOP-5596 for the EnumSet problem. I have tried to add the EnumSet support in ObjectWritable, it seems will not need much work to do.  

> 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, Hadoop-5438-2009-03-31.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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