I use left join to insert records in Hive. When I set limit 1 query, but for all record queries, it stays at 99% to reduce jobs.
Insert overwrite table tablename select a.id, b.name from a le
Category: Hadoop
Hadoop is a distributed system infrastructure developed by the Apache Foundation. Users can develop distributed programs without understanding the underlying details of distributed. Make full use of the power of clusters for high-speed computing and storage. Hadoop implements a distributed file system (Hadoop Distributed File System), referred to as HDFS. HDFS has the characteristics of high fault tolerance and is designed to be deployed on low-cost hardware; and it provides high throughput (high throughput) to access application data, suitable for those with large data sets (large data sets). set) application. HDFS relaxes the requirements of POSIX and can access data in the file system in the form of streaming access. The core design of the Hadoop framework is: HDFS and MapReduce. HDFS provides storage for massive amounts of data, while MapReduce provides calculations for massive amounts of data.
Hadoop – Is Cassandra for OLAP or OLTP or both?
Cassandra does not comply with ACID like RDBMS, but CAP. Therefore, Cassandra selects AP from CAP and leaves it to the user for adjustment consistency.
I definitely can’t use it. Cassandra conduct
Hadoop – Kafka Spark streaming: Unable to read
I am integrating Kafka and Spark, using spark-streaming. I created a theme as a producer of Kafka:
bin/kafka-topics.sh –create –zookeeper localhost:2181 –replication-factor 1 –partitions
Hadoop (1) Ali Cloud Hadoop Cluster Configuration
Three ECS cloud servers
1.1 Create /bigdata directory
mkdir /bigdata
cd /bigdata
mkdir /app 1.2 Modify the host name node01, node02, node03
1.3 Modify the hosts file
vim /e
Hadoop SQOOP instance
hadoop sqoop (instance) day-1 sqoop: is an open source tool, mainly used to transfer data between Hadoop and traditional databases (mysql). Import data from a relational database into Hadoop’s HDFS
How to read the ORC file in the Hadoop stream?
I want to read the ORC file in mapreduce on Python. I try to run it:
hadoop jar /usr /lib/hadoop/lib/hadoop-streaming-2.6.0.2.2.6.0-2800.jar
-file /hdfs/price/mymapper.py
-mapper’/usr/local
Hive Compression Type Test
Background:
1) 4 different types of tables have been created
2) Clean up the data in the hxh2, hxh3, and hxh4 tables, and keep the data in hxh1. The data size of the hxh1 table is: 74.1
Hadoop Hive-2.3.5 installation
hadoop hive-2.3.5 installation:
Unzip the file: [[email protected] opt]# tar -zxvf apache-hive-2.3.5-bin.tar.gz -C /opt
Establish a soft connection: [[email protected] opt]# ln -s apach
HDFS advantages and disadvantages
Brief description of HDFS architecture
1. Introduction to HDFS
HDFS (Hadoop distributed File System): Hadoop distributed file system. It is developed based on the needs of streaming dat
Hive Advanced Query 1
hadoop hive advanced query select basics 1.0 general query
1)select * from table_name< /p> 2)select * from table_name where name=’….’ limit 1;
1.1cte and nested query
1)with t a