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Oozie is a workflow scheduler system to manage Apache Hadoop jobs. It is integrated with the rest of the Hadoop stack supporting several types of Hadoop jobs such as Java MapReduce, Streaming MapReduce, Pig, Hive and Sqoop. Oozie is a scalable, reliable and extensible system. This technology is used in production at Yahoo!, running more than 200,000 jobs every day.
Features:
- Execute and monitor workflows in Hadoop
- Periodic scheduling of workflows
- Trigger execution of data availability
- HTTP and command line interface and web console
Workflow – Directed Acyclic Graph of Jobs:
Workflow Example:
<workflow-app nome='wordcount –wf’> <start to= ‘wordcount’/> <action name=’Wordcount'> <map-reduce> <job-tracker>foo.com:9001</job-tracker> <name-node>hdfs://bar.com:9000</name-node> <configuration> <property> <name>mapred.input.dir</name> <value>${inputDir}</value,> </property> <property> <name>mapred.output.dir</name> <value> ${outputDir}</value> </property> </configuration> </map-reduce> <ok to='end’/> <error to='kill'/> </action> <kill name='kill'/> <end name='end'/> </Workflow-app>
Workflow Definition:
A workflow definition is a DAG with control flow nodes or action nodes, where the nodes are connected by transitions arrows.
Control Flow Nodes:
The control flow provides a way to control the Workflow execution path. Flow control operations within the workflow applications can be done through the following nodes:
- Start/end/kill
- Decision
- Fork/join
Action Nodes:
- Map-reduce
- Pig
- HDFS
- Sub-workflow
- Java – Run custom Java code
Workflow Application:
Workflow application is a ZIP file that includes the workflow definition and the necessary files to run all the actions. It contains the following files:
- Configuration file – config-default.xml
- App files – lib/ directory with JAR and SO files
- Pig scripts
Application Deployment:
$ hadoop fs-put wordcount-wf hdfs://bar.com:9000/usr/abc/wordcount
Workflow Job Parameters:
$ cat job.properites Oozie.wf.application.path=hdfs://bar.com:9000/usr/abc/wordcount Input=/usr/abc/input-data Output=/usr/abc/output-data
Job Execution:
$ oozie job –run –config job.properties Job:1-20090525161321-oozie-xyz-W
Got a question for us? Mention them in the comments section and we will get back to you.
sir how to schedule job using crontab
Hey Rajiv, thanks for checking out our blog. Please refer to the steps given below to step up cron job:
1. Prepare SQL to be run on using CRON
2. See below for example of code which needs to be added to SQL code for a cron job
.logon server/user_id, Teradata password
For example :
.logon Mozart/akatarni,Welcome1
ADD THE SQL CODE HERE
.logoff
.quit
.exit
3. WinSCP – this is the file transfer application that is used to transfer the .SQL code file to the server.
a. Open “WinSCP”, Server name = phximdsas02.phx.ebay.com
b. Give login id and SAS password
c. Copy the code from your system to server window, in the attached snap shot we have copied “ask_lstg.sql” from genpact(personal system) to server window.
i. Left window shows your personal computer and right one is server
4. Open “Putty”. Use server phximdsas02.phx.ebay.com.
https://uploads.disquscdn.com/images/78d54b229f0ce485a72b7984a886306720904f6e58179446069905356f639f94.png
5. At the prompt, enter SAS credentials. After entering the password , you will see the attached window.
https://uploads.disquscdn.com/images/d89991fa7351bb7a80085c13e9ec8028f333f79c3ab3e6da6c406491ceb53dde.png
6. To open the editor :
a. Type export EDITOR=vi <hit enter>
b. Type crontab -e <hit enter>
i. This command edits your crontab file, or create one if it doesn’t already exist.
c. Press “i” to start typing
d. Press <ESC> to get out of insert mode
7. Then make the cron job entry:
A crontab entry has five fields for specifying day, date and time followed by the command to be run at that interval.
00 06 * * * /usr/bin/bteq <fake_lstg.sql> fake_lstg.LOG 2>&1
The above will run the code at 06:00 hours every day
In the above example, “fake_lstg.sql” is SQL file, “fake_lstg.LOG” is the log file where results will appear
15 20 * * 0 /usr/bin/bteq <fake_lstg.sql> fake_lstg.LOG 2>&1
The above will run the code at 20:15 hours every Sunday
https://uploads.disquscdn.com/images/4b910f3e7b76f35e76b9e9a338c5f547932c7c2e897d8b8a109c15c224fa0e01.png
8. Keep adding lines to the crontab file to schedule more job.
a. The easiest way to add a line is to be at the first character in the file, then in ESC mode,
click <shift> + O (case sensitive). This adds a new line above the current one.
9. To move around the file, in ESC mode
“l” – move right
“h” – move left
“j” – move down
“k” – move up
10. To save the crontab file and exit, press <ESC>, then :wq
a. To exit the file WITHOUT saving, press <ESC>, the :q!
11. Type Exit at the Unix prompt to exit Putty.
12. The cron job should run at the specified time
13. Check the *.LOG file to make sure code ran successfully.
Hope this helps. Cheers!
sir thanks for giving answer to my question..its helpful form me…good and fine description..thanks to u sir
Hi,
Suppose we want to use the output of Hive Job as an input to Mapreduce Job. How can we achieve this??
Hey Sankalp, thanks for checking out our blog. With regard to your query, first we can store the output of hive in hdfs and then we can execute it as an input file for mapreduce code.
Storing the output of hive.
INSERT OVERWRITE DIRECTORY ‘/path/to/output/dir’
ROW FORMAT DELIMITED
FIELDS TERMINATED BY ‘,’
select books from table;
Hope this helps. Cheers!