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oldrat：
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Kafka: High Qulity Posts
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Different kinds of clustering problems
EXCLUSIVE CLUSTERING In exclusive clustering, an item belongs exclusively to one cluster, not several.
OVERLAPPING CLUSTERING What if we wanted to do non-exclusive clustering; that is, put Harry Potter not only in fiction but also in a young adult cluster ...
K-means Algorithm
The k-means algorithm will start with an initial set of k centroid points. The algorithm does multiple rounds of processing and refines the centroid locations until the iteration max-limit criterion is reached or until the centroids converge to a fixed point from which they don’t ...
Transforming data into vectors
In Mahout, vectors are implemented as three different classes
DenseVector can be thought of as an array of doubles, whose size is the numberof features in the data. Because all the entries in the array are preallocatedregardless of whether the value is 0 or not, we ...
db.products.findOne({'slug': 'wheel-barrow-9092'})db.categories.findOne({'_id': product['main_cat_id']})
<=>
db.products.find({'slug': 'wheel-barrow-9092'}).limit(1)
db.reviews.find({'product_id': product['_id']})
db.reviews.find({'product_id': product['_id']}).skip(0).limit(12)
db.revie ...
Prepare ENV
download mongo-java-driver from http://central.maven.org/maven2/org/mongodb/mongo-java-driver
compile mongo-hadoop-connector for hadoop2.3.0
alter build.gradle to change hadoop-version to 2.3 and delete related download dependencies task
#./gradlew jar
distribute the aboves jars to ...
log4j configuration
- 博客分类：
- Java
转http://blog.csdn.net/azheng270/article/details/2173430/
Log4J的配置文件(Configuration File)就是用来设置记录器的级别、存放器和布局的，它可接key=value格式的设置或xml格式的设置信息。通过配置，可以创建出Log4J的运行环境。
1. 配置文件Log4J配置文件的基本格式如下：
#配置根Loggerlog4j.rootLogger = [ level ] , appenderName1 , appenderName2 , …#配置日志信息输出目的地Appenderlog4j.ap ...
How the drivers work
All MongoDB drivers perform three major functions.
First, they generateMongoDB object IDs. These are the default values stored in the _id field of all docu-ments.
Next, the drivers convert any language-specific representation of documents to and from BSON, the binary data fo ...
MongoDB is a database management system designed for web applications and internet infrastructure. The data model and persistence strategies are built for high read and write throughput and the ability to scale easily with automatic failover.
Document-based data model can represent rich, hierar ...
MongoDB
Download
#git clone https://github.com/mongodb/mongo
To install dependencies on Ubuntu systems:
#sudo apt-get install aptitude
#sudo aptitude install scons build-essential
#sudo aptitude install libboost-filesystem-dev libboost-program-options-dev libboost-system-dev libboost-thread- ...
Persistence options
Within Redis, there are two different ways of persisting data to disk. One is a method called snapshotting that takes the data as it exists at one moment in time and writes it to disk. The other method is called AOF, or append-only file, and it works by copying incoming write c ...
Commands in Redis
- 博客分类：
- Redis
Strings
Lists
Sets
Hashes
Sorted sets
Redis: Introduction 1
- 博客分类：
- Redis
What is Redis?
Redis is a very fast non-relational database that stores a mapping of keys to five different types of values.Redis supports in-memory persistent storage on disk, replication to scale read performance, and client-side sharding 1 to scale write performance.
Difference with other data ...
Hadoop and MongoDB Use Cases
The following are some example deployments with MongoDB and Hadoop. The goal is to provide a high-level description of how MongoDB and Hadoop can fit together in a typical Big Data stack. In each of the following examples MongoDB is used as the “operational” real-time ...
Redis: install
- 博客分类：
- Redis
wget http://download.redis.io/redis-stable.tar.gz
tar xvzf redis-stable.tar.gz
cd redis-stable
make
edit ~/.bashrc add
export REDIS_HOME=/path/to/redis
export PATH=$PATH:$REDIS_HOME/src
References
http://redis.io/topics/quickstart
Redis is a very cool open-source key-value store that can add instant value to your Hadoop installation. Since keys can contain strings, hashes, lists, sets and sorted sets, Redis can be used as a front end to serve data out of Hadoop, caching your ‘hot’ pieces of data in-memory for fast acces ...