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Editor to share with you how to use Cassandra, I believe that most people do not know much about it, so share this article for your reference, I hope you can learn a lot after reading this article, let's go to know it!

First, let's introduce the installation and startup of Cassandra:

There are 3 installation options for Cassandra:

1. Community Edition:

Address: http://planetcassandra.org/Download/DataStaxCommunityEdition

Description: free of charge for development and production environment

two。 Enterprise edition

Address: http://www.datastax.com/download

Description: the development environment is free and the production environment requires license

3. Open source version

Address: http://www.datastax.com/download

Github address: https://github.com/apache/cassandra

Installation method, Cassandra has yum,tarball installation mode, we choose tarball installation:

According to the download address above, we download and extract the * .tar.gz file

As you can see, bin,conf, tools and other directories are included after decompression.

Run Cassandra directly under the bin directory

Start Cassandra:

Bin/cassandra

Cassandra will produce diary files in the log directory. Check "statejump to normal" to indicate that the startup is successful.

INFO 15:09:21 Node localhost/127.0.0.1 state jump to normal

II. CQL Foundation

It mainly includes the following knowledge points:

What is CQL?

What is Keyspaces?

What is Tables?

Basic datatypes

What is CQL?

The full name of CQL: Cassandra Query Language, which is Cassandra query syntax, similar to SQL.

SELECT * FROM users

What is Keyspaces?

Keyspaces is the outermost / top-level container of data in Cassandra, similar to the concept of schema for relational databases. There is an attribute Replication that defines the global behavior across the entire Keyspaces scope.

CREATE KEYSPACE killrvideoWITH REPLICATION = {'class':' SimpleStrategy', 'replication_factor': 1}

Toggle Keyspaces method: use USE

USE killrvideo

What is Tables?

Keyspaces contains tables,tables contains data, similar to a table container in a relational database.

Basic data types:

Type description

Text

UTF-8 coding

Varchar is the same as text

Int

Symbolic type

32 bit

Timestamp

64-bit integer

The number of seconds stored from 00:00:00 on 1970-01-01

UUID and TIMEUUID types

Used to replace integer id (because Cassandra is a distributed database)

Full name of UUID: Universally Unique Identifier

For example: 52b11d6d-16e2-4ee2-b2a9-5ef1e9589328

Generated by uuid ()

TIMEUUID: embed timestamp in UUID values

For example: 1be43390-9fe4-11e3-8d05-425861b86ab6

Sortable, generated by now ()

INSERT syntax:

Similar to relational grammar

INSERT INTO users (user_id, first_name, last_name) VALUES (uuid (), 'Joseph',' Chu')

SELECT syntax:

Similar to relational grammar

SELECT * FROM users;SELECT first_name, last_name FROM users;SELECT * FROM users WHERE user_id = 4b516be3-ddf0-4c43murbab6murbabb91d674b64a5; above is all the content of this article "how to use Cassandra". Thank you for reading! I believe we all have a certain understanding, hope to share the content to help you, if you want to learn more knowledge, welcome to follow the industry information channel!

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