Apache Cassandra入门指南[长期连载]

jieforest · 发表于 2012-7-11 20:08

The repair command replicates any updates missed due to downtime or loss of connectivity. This command ensures consistency across the cluster and obviates the tombstones. You will want to do this periodically on each node in the cluster (within the window before tombstone purge).

Monitoring

Cassandra has support for monitoring via JMX, but the simplest way to monitor the Cassandra node is by using OpsCenter, which is designed to manage and monitor Cassandra database clusters. There is a free community edition as well as an enterprise edition that provides management of Apache SOLR and Hadoop.

Simply download mx4j and execute the following:

> cp $MX4J_HOME/lib/mx4j-tools.jar $CASSANDRA_HOME/lib

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jieforest · 发表于 2012-7-11 20:10

The following are key attributes to track per column family.

jieforest · 发表于 2012-7-11 20:11

Backup

OpsCenter facilitates backing up data by providing snapshots of the data. A snapshot creates a new hardlink to every live SSTable. Cassandra also provides online backup facilities using nodetool. To take a snapshot of the data on the cluster, invoke:

>$CASSANDRA_HOME/bin/nodetool snapshot

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This will create a snapshot directory in each keyspace data directory. Restoring the snapshot is then a matter of shutting down the node, deleting the commitlogs and the data files in the keyspace, and copying the snapshot files back into the keyspace directory.

jieforest · 发表于 2012-7-11 20:14

CLIENT LIBRARIES

Cassandra has a very active community developing libraries in different languages.

Java

CQL

jieforest · 发表于 2012-7-12 19:44

PHP CQL

Python

jieforest · 发表于 2012-7-12 19:45

Ruby

REST

jieforest · 发表于 2012-7-13 10:49

.NET

Node.js

jieforest · 发表于 2012-7-13 10:51

本帖最后由 jieforest 于 2012-7-13 10:51 编辑

There are also community supported client libraries for .NET [http://code.google.com/p/cassandra-sharp/] and Node.js [https://github.com/racker/node-cassandra-client]

Command Line Interface (CLI)
Cassandra also provides a Command Line Interface (CLI) through which you can perform all schema related changes. It also allows you to manipulate data.

Hadoop Support

DataStax Enterprise provides Cassandra with an enhanced Hadoop distribution that is compatible with existing HDFS, Hadoop, and Hive tools and utilities. Cassandra also provides out-of-the-box support for Hadoop.

To see the canonical word count example, take a look at:
https://github.com/apache/cassan ... s/hadoop_word_count

jieforest · 发表于 2012-7-13 10:52

over.