1. Boxing, unpacking or aliases many of the introduction of C #. NET learning experience books on the introduction of the int-> Int32 is a boxing process, the reverse is the process of unpacking. This is true of many other variable types, such as short <-> int16,long <->int64. For the average programmer, it is not necessary to understand this process, because these boxes and unboxing actions can be automatically completed, do not need to write code to intervene. But we need to remember that ...
This article is my second time reading Hadoop 0.20.2 notes, encountered many problems in the reading process, and ultimately through a variety of ways to solve most of the. Hadoop the whole system is well designed, the source code is worth learning distributed students read, will be all notes one by one post, hope to facilitate reading Hadoop source code, less detours. 1 serialization core Technology The objectwritable in 0.20.2 version Hadoop supports the following types of data format serialization: Data type examples say ...
To use Hadoop, data consolidation is critical and hbase is widely used. In general, you need to transfer data from existing types of databases or data files to HBase for different scenario patterns. The common approach is to use the Put method in the HBase API, to use the HBase Bulk Load tool, and to use a custom mapreduce job. The book "HBase Administration Cookbook" has a detailed description of these three ways, by Imp ...
Pig is a Yahoo donated project to Apache and is currently in the Apache incubator, but the basic functionality is already available. Today I would like to introduce you to this useful pig.pig is Sql-like language, is built on the mapreduce of an advanced query language, Some operations are compiled into the MapReduce model's map and reduce, and users can define their own capabilities. Yahoo Grid Computing department developed another clone of Google's project: Sawzall. Supported operations ...
HBase is a distributed, column-oriented, open source database based on Google's article "Bigtable: A Distributed Storage System for Structured Data" by Fay Chang. Just as Bigtable takes advantage of the distributed data storage provided by Google's File System, HBase provides Bigtable-like capabilities over Hadoop. HBase Implements Bigtable Papers on Columns ...
Hive data type 1. Basic type Integer type: Tinyint,smallint,int,bigint, the above types correspond to the Byte,short,int,long in Java respectively. Decimal Type: Float,double Boolean type: Boolean string type: String,varchar,char 2. Complex Type Array,map,struct,timestamp (DATE) Common ...
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