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HDFS-11433. Document missing usages of OfflineEditsViewer processors. Contributed by Yiqun Lin.

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Yiqun Lin 2017-02-25 10:00:05 +08:00
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hadoop-hdfs-project/hadoop-hdfs/src/site/markdown/HdfsEditsViewer.md
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@ -40,9 +40,80 @@ The Offline Edits Viewer provides several output processors (unless stated other
Usage
-----
### XML Processor
XML processor can create an XML file that contains the edits log information. Users can specify input and output file via -i and -o command-line.
bash$ bin/hdfs oev -p xml -i edits -o edits.xml
XML processor is the default processor in Offline Edits Viewer, users can also use the following command:
bash$ bin/hdfs oev -i edits -o edits.xml
| Flag | Description |
This would result in the following output:
<?xml version="1.0" encoding="UTF-8"?>
<EDITS>
<EDITS_VERSION>-64</EDITS_VERSION>
<RECORD>
<OPCODE>OP_START_LOG_SEGMENT</OPCODE>
<DATA>
<TXID>1</TXID>
</DATA>
</RECORD>
<RECORD>
<OPCODE>OP_UPDATE_MASTER_KEY</OPCODE>
<DATA>
<TXID>2</TXID>
<DELEGATION_KEY>
<KEY_ID>1</KEY_ID>
<EXPIRY_DATE>1487921580728</EXPIRY_DATE>
<KEY>2e127ca41c7de215</KEY>
</DELEGATION_KEY>
</DATA>
</RECORD>
<RECORD>
...remaining output omitted...
### Binary Processor
Binary processor is the opposite of the XML processor. Users can specify input XML file and output file via -i and -o command-line.
bash$ bin/hdfs oev -p binary -i edits.xml -o edits
This will reconstruct an edits log file from an XML file.
### Stats Processor
Stats processor is used to aggregate counts of op codes contained in the edits log file. Users can specify this processor by -p option.
bash$ bin/hdfs oev -p stats -i edits -o edits.stats
The output result of this processor should be like the following output:
VERSION : -64
OP_ADD ( 0): 8
OP_RENAME_OLD ( 1): 1
OP_DELETE ( 2): 1
OP_MKDIR ( 3): 1
OP_SET_REPLICATION ( 4): 1
OP_DATANODE_ADD ( 5): 0
OP_DATANODE_REMOVE ( 6): 0
OP_SET_PERMISSIONS ( 7): 1
OP_SET_OWNER ( 8): 1
OP_CLOSE ( 9): 9
OP_SET_GENSTAMP_V1 ( 10): 0
...some output omitted...
OP_APPEND ( 47): 1
OP_SET_QUOTA_BY_STORAGETYPE ( 48): 1
OP_INVALID ( -1): 0
The output is formatted as a colon separated two column table: OpCode and OpCodeCount. Each OpCode corresponding to the specific operation(s) in NameNode.
Options
-------
| Flag | Description |
|:---- |:---- |
| [`-i` ; `--inputFile`] *input file* | Specify the input edits log file to process. Xml (case insensitive) extension means XML format otherwise binary format is assumed. Required. |
| [`-o` ; `--outputFile`] *output file* | Specify the output filename, if the specified output processor generates one. If the specified file already exists, it is silently overwritten. Required. |