Rollback Command

Start Hadoop start-all.sh Turn off Hadoop stop-all.sh View the file list to view the files in the/user/admin/aaron directory in HDFs. 　　Hadoop Fs-ls/user/admin/aaron Lists all the files (including the files under subdirectories) in the/user/admin/aaron directory in HDFs. Hadoop fs-lsr/user ...

1 Hadoop fs ----------------------------------------------- --------------------------------- The hadoop subcommand set executes on the root of the / home directory on the machine Is / user / root --------------------------------------------- ----------...

Overview All Hadoop commands are raised by the Bin/hadoop script. Do not specify parameters running the Hadoop script prints the description of all commands. Usage: Hadoop [--config confdir] [COMMAND] [generic_options] [command_options] Hadoop has an option parsing framework for parsing general options and running classes. Command option description--config confdir overwrite default configuration directory ...

As an outstanding representative of the Object relational database, Oracle is undoubtedly the most powerful. Whether it's the size of the database, the support of multimedia data types, the parallelism of SQL operations replication, or the security services, Oracle is much stronger than Sybase, Informix, Added to the latest version of the Oracle8.0.4 is to enhance the characteristics of this, but also introduced a number of new features, such as: Data partitioning (partitioning), Object-relational technology (objects relational T ...

Original address: http://hadoop.apache.org/core/docs/current/hdfs_user_guide.html Translator: Dennis Zhuang (killme2008@gmail.com), Please correct me if there is a mistake. Objective This document can be used as a starting point for users of distributed file systems using Hadoop, either by applying HDFS to a Hadoop cluster or as a separate distributed file system. HDFs is designed ...

Objective the goal of this document is to provide a learning starting point for users of the Hadoop Distributed File System (HDFS), where HDFS can be used as part of the Hadoop cluster or as a stand-alone distributed file system. Although HDFs is designed to work correctly in many environments, understanding how HDFS works can greatly help improve HDFS performance and error diagnosis on specific clusters. Overview HDFs is one of the most important distributed storage systems used in Hadoop applications. A HDFs cluster owner ...

We want to do not only write SQL, but also to do a good performance of the SQL, the following for the author to learn, extract, and summarized part of the information to share with you! (1) Select the most efficient table name order (valid only in the Rule-based optimizer): The ORACLE parser processes the table names in the FROM clause in Right-to-left order, and the last table in the FROM clause (the underlying table driving tables) is processed first, In the case where multiple tables are included in the FROM clause, you must select the table with the least number of records as the underlying table. If...

Compared with Vm,docker, it has obvious advantages in light weight, configuration complexity and resource utilization. With the maturing of Docker technology, more and more enterprises begin to consider improving their IT system through Docker. This article enumerates some Docker practical application scenes, in order to be able to play the role of the trigger, to help us to use Docker more conveniently. Applications packaged with packages made of RPM, gems, and so on may be clear, each package depends on which version of the library, often need to be explicitly written in ...

Recently released Hive 0.13 ACID semantic transaction mechanism used to ensure transactional atomicity, consistency and durability at the partition layer, and by opening Zoohttp: //www.aliyun.com/zixun/aggregation/19458.html "> Keeper or in-memory lock mechanism to ensure transaction isolation.Data flow intake, slow changes in dimension, data restatement of these new use cases in the new version has become possible, of course, there are still some deficiencies in the new Hive, Hive ...

kubernetes learning record (7) - Elastic scaling and rolling upgrade. Elastic Scalability Elastic scaling refers to adapting to load variations and providing resources in a resilient, scalable way. Pod's flexible scaling is to modify the number of Replica Replicator Controller. Can be achieved through the Kubectl scale command. Create Replication Controller test-rc.yaml apiVersion: v1 kind: Replicatio ...