Having experienced first hand the difference between s3a and s3n – 7.9GB of data transferred on s3a was around ~7 minutes while 7.9GB of data on s3n took 73 minutes [us-east-1 to us-west-1 unfortunately in both cases; Redshift and Lambda being us-east-1 at this time] this is a very important piece of the stack to … Read more
OK, you are making two big mistakes. 1. Let’s start with a quick exegesis of some parts of the Oozie documentation (V4.2) Workflow Functional Specification has a section 19 about Global Configuration has sections 3.2.x about core Action types i.e. MapReduce, Pig, Java, etc. the XML schema specification clearly shows the <global> element Sqoop action … Read more
You can’t mix bits of Hadoop and expect things to work. It’s not just the close coupling between internal classes in hadoop-common and hadoop-aws, its things like the specific version of the amazon-aws SDK the hadoop-aws module was built it. If you get ClassNotFoundException or MethodNotFoundException stack traces when trying to work with s3a:// URLs, … Read more
Using JVM gateway maybe is not so elegant, but in some cases the code below could be helpful: URI = sc._gateway.jvm.java.net.URI Path = sc._gateway.jvm.org.apache.hadoop.fs.Path FileSystem = sc._gateway.jvm.org.apache.hadoop.fs.FileSystem Configuration = sc._gateway.jvm.org.apache.hadoop.conf.Configuration fs = FileSystem.get(URI(“hdfs://somehost:8020”), Configuration()) status = fs.listStatus(Path(‘/some_dir/yet_another_one_dir/’)) for fileStatus in status: print(fileStatus.getPath())
For some reason, the jar hadoop-aws-[version].jar which contains the implementation to NativeS3FileSystem is not present in the classpath of hadoop by default in the version 2.6 & 2.7. So, try and add it to the classpath by adding the following line in hadoop-env.sh which is located in $HADOOP_HOME/etc/hadoop/hadoop-env.sh: export HADOOP_CLASSPATH=$HADOOP_CLASSPATH:$HADOOP_HOME/share/hadoop/tools/lib/* Assuming you are using Apache … Read more
Adding to other answers. Is it necessary that spark is installed on all the nodes in the yarn cluster? No, If the spark job is scheduling in YARN(either client or cluster mode). Spark installation is needed in many nodes only for standalone mode. These are the visualizations of spark app deployment modes. Spark Standalone Cluster … Read more
Finally I stumbled on the constant static final String HADOOP_USER_NAME = “HADOOP_USER_NAME”;` in the UserGroupInformation class. Setting this either as an environment variable, as a Java system property on startup (using -D) or programmatically with System.setProperty(“HADOOP_USER_NAME”, “hduser”); makes Hadoop use whatever username you want for connecting to the remote Hadoop cluster.
Just ran into this problem running mahout from CDH4 in standalone mode in my MacBook Air. The issue is that a /tmp/hadoop-xxx/xxx/LICENSE file and a /tmp/hadoop-xxx/xxx/license directory are being created on a case-insensitive file system when unjarring the mahout jobs. I was able to workaround this by deleting META-INF/LICENSE from the jar file like this: … Read more
As of Hive version 0.14.0: INSERT…VALUES, UPDATE, and DELETE are now available with full ACID support. INSERT … VALUES Syntax: INSERT INTO TABLE tablename [PARTITION (partcol1[=val1], partcol2[=val2] …)] VALUES values_row [, values_row …] Where values_row is: ( value [, value …] ) where a value is either null or any valid SQL literal UPDATE Syntax: … Read more
The reduce phase has 3 steps: shuffle, sort, reduce. Shuffle is where the data is collected by the reducer from each mapper. This can happen while mappers are generating data since it is only a data transfer. On the other hand, sort and reduce can only start once all the mappers are done. You can … Read more