BeanFactoryPostProcessor in Spring Framework
BeanFactoryPostProcessor interface in Spring resides in org.springframework.beans.factory.config package. BeanFactoryPostProcessor implementation is used to read the configuration metadata and...
View ArticleJDBCTemplate With ResultSetExtractor Example in Spring
In the post Select Query Using JDBCTemplate in Spring Framework we have already seen an example of extracting data from ResultSet using RowMapper. A RowMapper is usually a simpler choice for ResultSet...
View Article@Import Annotation in Spring JavaConfig
If you are using JavaConfig in Spring to configure the bean definitions then, in order to modularize your configurations you can use @Import annotation.@Import annotation in Spring JavaConfig allows...
View ArticleServiceLocatorFactoryBean in Spring Framework
ServiceLocatorFactoryBean in Spring framework as the name suggests is an implementation of service locator design pattern and helps with locating the service at run time.ServiceLocatorFactoryBean helps...
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Internationalization (i18n) Using MessageSource in Spring
In an interview if difference between BeanFactory and ApplicationContext is asked one of the reason given by people to use ApplicationContext is the support for internationalization provided by...
View ArticleHow to Handle Missing And Under Replicated Blocks in HDFS
In this post we’ll see how to handle missing or corrupt blocks in HDFS and how to handle under replicated blocks in HDFS. How to get information about corrupt or missing blocksFor getting information...
View ArticleHow to Write a Map Only Job in Hadoop MapReduce
In a MapReduce job in Hadoop you generally write both map function and reduce function. Map function to generate (key, value) pairs and reduce function to aggregate those (key, value) pairs but you may...
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Parquet File Format in Hadoop
Apache Parquet is a columnar storage format available to any project in the Hadoop ecosystem (Hive, Hbase, MapReduce, Pig, Spark) What is columnar storage formatIn order to understand Parquet file...
View ArticleHow to Read And Write Parquet File in Hadoop
This post shows how to use Hadoop Java API to read and write Parquet file. You will need to put following jars in class path in order to read and write Parquet files in Hadoop....
View ArticleConverting Text File to Parquet File Using Hadoop MapReduce
This post shows how to convert existing data to Parquet file format using MapReduce in Hadoop. In the example given here Text file is converted to Parquet file. You will need to put following jars in...
View ArticleChaining MapReduce Job in Hadoop
While processing data using MapReduce you may want to break the requirement into a series of task and do them as a chain of MapReduce jobs rather than doing everything with in one MapReduce job and...
View ArticlePredefined Mapper And Reducer Classes in Hadoop
Hadoop framework comes prepackaged with many Mapper and Reducer classes. This post explains some of these predefined Mappers and Reducers in Hadoop and shows examples using the predefined Mappers and...
View ArticleHow to Check Hadoop MapReduce Logs
In your Hadoop MapReduce job if you are wondering how to put logs or where to check MapReduce logs or even System.out statements then this post shows the same. Note that here accessing logs is shown...
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Shuffle And Sort Phases in Hadoop MapReduce
When you run a MapReduce job and mappers start producing output internally lots of processing is done by the Hadoop framework before the reducers get their input. This whole internal processing is...
View ArticleApache Avro Format in Hadoop
Apache Avro file format created by Doug cutting is a data serialization system for Hadoop. Avro provides simple integration with dynamic languages. Avro implementations for C, C++, C#, Java, PHP,...
View ArticleHow to Read And Write Avro File in Hadoop
In this post we’ll see a Java program to read and write Avro files in Hadoop environment. Jars downloadFor reading and writing an Avro file using Java API you will need to download following jars and...
View ArticleUsing Avro File With Hadoop MapReduce
In this post we’ll see how to use Avro file with Hadoop MapReduce. Avro MapReduce jarYou will need to download following jar and put it into project’s class path. avro-mapred-1.8.2.jar Avro MapReduce...
View ArticleToolRunner and GenericOptionsParser in Hadoop
GenericOptionsParser is a utility class in Hadoop which resides in org.apache.hadoop.utilpackage. GenericOptionsParser class helps in setting options through command line. It parses the command line...
View ArticleWhat Are Counters in Hadoop MapReduce
If you run a MapReduce job you would have seen a lot of counters displayed on the console after the MapReduce job is finished (You can also check the counters using UI while the job is running). These...
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Using Combiner to Improve MapReduce Performance in Hadoop
In this post we’ll see what is combiner in Hadoop and how combiner helps in speeding up the shuffle and sort phase in Hadoop MapReduce. What is combiner in HadoopGenerally in a MapReduce job, data is...
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