Is there anyway to have Sqoop connected to different Hadoop clusters so that multiple Sqoop jobs can be created to export data to multiple hadoop clusters?
to export data to multiple hadoop clusters
If data is going into Hadoop, that's technically a Sqoop import
Not clear how you currently manage different clusters from one machine, but you would need to have the conf folder of all environments available for Sqoop to read
The sqoop command-line program is a wrapper which runs the bin/hadoop script shipped with Hadoop. If you have multiple installations of Hadoop present on your machine, you can select the Hadoop installation by setting the $HADOOP_HOME environment variable.
For example:
$ HADOOP_HOME=/path/to/some/hadoop sqoop import --arguments...
or:
$ export HADOOP_HOME=/some/path/to/hadoop
$ sqoop import --arguments...
If $HADOOP_HOME is not set, Sqoop will use the default installation location for Cloudera’s Distribution for Hadoop, /usr/lib/hadoop.
The active Hadoop configuration is loaded from $HADOOP_HOME/conf/, unless the $HADOOP_CONF_DIR environment variable is set
https://sqoop.apache.org/docs/1.4.6/SqoopUserGuide.html#_controlling_the_hadoop_installation
Depending on how you setup Hadoop, Hortonworks only has Sqoop 1, while Cloudera (and maybe MapR) have Sqoop2, and those instructions are probably different since Sqoop2 architecture is different.
Related
If i install hadoop using 'hadoop' user, and install hive using 'hive' user on same node(Pseudo distribution mode).
How can my hive access hadoop?
when i input 'hive --version', i receive error like this:
Cannot find hadoop installation: $HADOOP_HOME or $HADOOP_PREFIX must be set or hadoop must be in the path.
The question is hive user have no right to access hadoop, but i don't know how to fix it.
Thanks a lot.
As the error says, $HADOOP_HOME or $HADOOP_PREFIX must be set or hadoop must be in the path.
So, edit /home/hive/.bash_profile, for example assuming you're on Linux, and add one of those values to set the environment variable to the downloaded Hadoop package
For example
export HADOOP_HOME=/opt/hadoop # example
export PATH=$HADOOP_HOME/bin:$PATH
Just wondering can sqoop run without a hadoop cluster? sort of in a standalone mode? Has anyone tried to run sqoop on spark, please share some experiences on it.
To run Sqoop commands (both sqoop1 and sqoop2), Hadoop is a mandatory prerequisite. You cannot run sqoop commands without the Hadoop libraries.
Sqoop works in local mode too, so it is not a requirement that the Hadoop daemons must be running. To run sqoop in local mode,
sqoop [tool-name] -fs local -jt local [tool-arguments]
Sqoop on Spark is still In-Progress. See SQOOP-1532
Can you tell me the exact command to import data from hdfs with two different haddop version one with hadoop 2.0.4 alpha and other 2.4.0 version? How can I use distcp command in this case?
When you have different versions use hftp instead of using the actual hdfs command. You can see examples on Cloudera website. Use the hftp on your source cluster and hdfs on your destination cluster address.
I'm having troubles understanding the relation between Hadoop and Pig.
I understand Pig's purpose is to hide the MapReduce pattern behind a scripting language, Pig Latin.
What I don't understand is how Hadoop and Pig are linked. So far, the only installation procedures seem to assume that pig is run on the same machine as the main hadoop node.
Indeed, it uses the hadoop configuration files.
Is this because pig only translates the scripts into mapreduce code and send them to hadoop ?
If that's the case, how could I configure Pig in order to make it send the scripts to a distant server ?
If not, does it mean we always need to have hadoop running within pig ?
Pig can run in two modes:
Local mode. In this mode Hadoop cluster is not used at all. All processes run in single JVM and files are read from the local filesystem. To run Pig in local mode, use the command:
pig -x local
MapReduce Mode. In this mode Pig converts scripts to MapReduce jobs and run them on Hadoop cluster. It is the default mode.
Cluster can be local or remote. Pig uses the HADOOP_MAPRED_HOME environment variable to find Hadoop installation on local machine (see Installing Pig).
If you want to connect to remote cluster, you should specify cluster parameters in the pig.properties file. Example for MRv1:
fs.default.name=hdfs://namenode_address:8020/
mapred.job.tracker=jobtracker_address:8021
You can also specify remote cluster address at the command line:
pig -fs namenode_address:8020 -jt jobtracker_address:8021
Hence, you can install Pig to any machine and connect to remote cluster. Pig includes Hadoop client, therefore you don't have to install Hadoop to use Pig.
I just started learning Hadoop and PIG (from last two days!) for one of my future project.
For experiments I've installed Hadoop (HDFS on default localhost:9000) as pseudo distributed mode and PIG (map-reduce mode).
When I initialized PIG by typing ./bin/pig command it launched GRUNT command line and I got message that pig connected with HDFS (localhost:9000), later I could successfully able to access HDFS thru pig.
I was expecting to perform some manual configuration for PIG to access HDFS (as per various internet articles).
My question is, from where PIG identified default HDFS configuration (localhost:9000)? I checked pig.properties but I didn't find anything there. I need this info as I might change default HDFS configuration in future.
BTW, I have HADOOP_HOME and PIG_HOME defined in my OS PATH variable.
When installing Pig (I assume v0.10.0) you have to tell how it will connect to the HDFS.
I don't know how you did this but generally this is done by adding the hadoop conf dir path to the PIG_CLASSPATH environment variable. You can also set HADOOP_CONF_DIR as well.
If you are starting the grunt shell Pig will locate the directory of the Hadoop configuration XMLs, and takes the value of fs.default.name (core-site.xml) and mapred.job.tracker (mapred-site.xml) , i.e: the location of the Namenode and JobTracker.
For reference you may have a look at the Pig shell script to see how env. variables are collected and evaluated.
PIG can connects to underlying HDFS in the 3 ways
1-
Pig uses HADOOP_HOME for finding the HADOOP client to Run.
your HADOOP_HOME should have been already setup in your bash_profile
export HADOOP_HOME=~/myHadoop/hadoop-2.5.2
2-
or else there might be possibility that your HADOOP_CONF_DIR has already been setup which contains the xml file for the hadoop configuration
export HADOOP_CONF_DIR=$HADOOP_HOME/etc/hadoop/
3-And if these are not setup you can also connect to underlying hdfs
by changing the pig.properties which is present under PIG_HOME/conf dir