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Cassandra vs MongoDB vs CouchDB vs Redis vs Riak vs HBase比较

Zou Yong — Sun, 09 Jan 2011 13:49:35 +0000

原文:

http://kkovacs.eu/cassandra-vs-mongodb-vs-couchdb-vs-redis

Cassandra vs MongoDB vs CouchDB vs Redis vs Riak vs HBase comparison

While SQL databases are insanely useful tools, their tyranny of ~15 years is coming to an end. And it was just time: I can’t even count the things that were forced into relational databases, but never really fitted them.

But the differences between "NoSQL" databases are much bigger than it ever was between one SQL database and another. This means that it is a bigger responsibility on software architects to choose the appropriate one for a project right at the beginning.

In this light, here is a comparison of Cassandra, Mongodb, CouchDB, Redis, Riak and HBase:

CouchDB

Written in: Erlang
Main point: DB consistency, ease of use
License: Apache
Protocol: HTTP/REST
Bi-directional (!) replication,
continuous or ad-hoc,
with conflict detection,
thus, master-master replication. (!)
MVCC – write operations do not block reads
Previous versions of documents are available
Crash-only (reliable) design
Needs compacting from time to time
Views: embedded map/reduce
Formatting views: lists & shows
Server-side document validation possible
Authentication possible
Real-time updates via _changes (!)
Attachment handling
thus, CouchApps (standalone js apps)
jQuery library included

Best used: For accumulating, occasionally changing data, on which pre-defined queries are to be run. Places where versioning is important.

For example: CRM, CMS systems. Master-master replication is an especially interesting feature, allowing easy multi-site deployments.

Redis

Written in: C/C++
Main point: Blazing fast
License: BSD
Protocol: Telnet-like
Disk-backed in-memory database,
but since 2.0, it can swap to disk.
Master-slave replication
Simple keys and values,
but complex operations like ZREVRANGEBYSCORE
INCR & co (good for rate limiting or statistics)
Has sets (also union/diff/inter)
Has lists (also a queue; blocking pop)
Has hashes (objects of multiple fields)
Of all these databases, only Redis does transactions (!)
Values can be set to expire (as in a cache)
Sorted sets (high score table, good for range queries)
Pub/Sub and WATCH on data changes (!)

Best used: For rapidly changing data with a foreseeable database size (should fit mostly in memory).

For example: Stock prices. Analytics. Real-time data collection. Real-time communication.

MongoDB

Written in: C++
Main point: Retains some friendly properties of SQL. (Query, index)
License: AGPL (Drivers: Apache)
Protocol: Custom, binary (BSON)
Master/slave replication
Queries are javascript expressions
Run arbitrary javascript functions server-side
Better update-in-place than CouchDB
Sharding built-in
Uses memory mapped files for data storage
Performance over features
After crash, it needs to repair tables

Best used: If you need dynamic queries. If you prefer to define indexes, not map/reduce functions. If you need good performance on a big DB. If you wanted CouchDB, but your data changes too much, filling up disks.

For example: For all things that you would do with MySQL or PostgreSQL, but having predefined columns really holds you back.

Cassandra

Written in: Java
Main point: Best of BigTable and Dynamo
License: Apache
Protocol: Custom, binary (Thrift)
Tunable trade-offs for distribution and replication (N, R, W)
Querying by column, range of keys
BigTable-like features: columns, column families
Writes are much faster than reads (!)
Map/reduce possible with Apache Hadoop
I admit being a bit biased against it, because of the bloat and complexity it has partly because of Java (configuration, seeing exceptions, etc)

Best used: When you write more than you read (logging). If every component of the system must be in Java. ("No one gets fired for choosing Apache’s stuff.")

For example: Banking, financial industry (though not necessarily for financial transactions, but these industries are much bigger than that.) Writes are faster than reads, so one natural niche is real time data analysis.

Riak

Written in: Erlang & C, some Javascript
Main point: Fault tolerance
License: Apache
Protocol: HTTP/REST
Tunable trade-offs for distribution and replication (N, R, W)
Pre- and post-commit hooks,
for validation and security.
Built-in full-text search
Map/reduce in javascript or Erlang
Comes in "open source" and "enterprise" editions

Best used: If you want something Cassandra-like (Dynamo-like), but no way you’re gonna deal with the bloat and complexity. If you need very good single-site scalability, availability and fault-tolerance, but you’re ready to pay for multi-site replication.

For example: Point-of-sales data collection. Factory control systems. Places where even seconds of downtime hurt.

HBase

(With the help of ghshephard)

Written in: Java
Main point: Billions of rows X millions of columns
License: Apache
Protocol: HTTP/REST (also Thrift)
Modeled after BigTable
Map/reduce with Hadoop
Query predicate push down via server side scan and get filters
Optimizations for real time queries
A high performance Thrift gateway
HTTP supports XML, Protobuf, and binary
Cascading, hive, and pig source and sink modules
Jruby-based (JIRB) shell
No single point of failure
Rolling restart for configuration changes and minor upgrades
Random access performance is like MySQL

Best used: If you’re in love with BigTable. And when you need random, realtime read/write access to your Big Data.

For example: Facebook Messaging Database (more general example coming soon)

Of course, all systems have much more features than what’s listed here. I only wanted to list the key points that I base my decisions on. Also, development of all are very fast, so things are bound to change. I’ll do my best to keep this list updated.

– Kristof

CouchDB
语言 Erlang
特征数据库一致性，易于使用
适合积累性的、较少改变的数据。或者是需要文档的多版本支持（？这句话翻译不好 Places where versioning is important）
场合 CRM CMS

Redis
语言 c/c++
特征非常快
适合总数据集快速变化且总量可预测
场合股票价格、实时分析、实时数据收集、实时通信

MongoDB
语言 c++
特征与sql风格类似（查询/索引）
适合动态查询; 索引比map/reduce方式更合适时; 需要CouchDB但数据变动更多时
场合任何用Mysql/PostgreSQL，但是无法忍受预先定义好所有列的时候

Cassandra
语言 java
适合写入比查询多
略（我个人也觉得不靠谱）

Riak
语言 c++/erlang javascript
据说有开源版和企业版
特征容错
适合需要Cassandra式的扩展性，但是不想惹麻烦
场合销售数据收集 … 反正坏一秒就很麻烦的场合

hbase
语言 java
类似 bigtable
适用随机读取

17 Useful Htaccess Tricks and Tips

Zou Yong — Sat, 25 Dec 2010 02:36:47 +0000

Introduction

Some people might not aware of the power of htaccess, I have 17 htaccess methods in this article which I have used or tested it before, and I think some of them are essential tricks and tips to protect your webserver against malicious attacks and other would able to perform simple tasks efficiently such as redirection and web server optimization.

Last but not least, if you have been looking for web hosting services, you might want to have a look at this unlimited web hosting.

General

The following htaccess will able to help you to achieve simple task such as redirection and web server optimization.

1. Set Timezone

Sometimes, when you using date or mktime function in php, it will show you a funny message regarding timezone. This is one of the way to solve it. Set timezone for your server. A list of supported timezone can be found here

SetEnv TZ Australia/Melbourne

2. SEO Friendly 301 Permanent Redirects

Why it’s SEO friendly? Nowadays, some modern serach engine has the capability to detect 301 Permanent Redirects and update its existing record.

Redirect 301 http://www.queness.com/home http://www.queness.com/

3. Skip the download dialogue

Usually when you try to download something from a web server you get a request asking whether you want to save the file or open it. To avoid that you can use the below code on your .htaccess file

AddType application/octet-stream .pdf
AddType application/octet-stream .zip
AddType application/octet-stream .mov

4. Skip www

One of the SEO guideline is, make sure there is only one URL pointing to your website. Therefore, you will need this to redirect all www traffic to non-ww, or the other way around.

RewriteEngine On
RewriteBase /
RewriteCond %{HTTP_HOST} ^www.queness.com [NC]
RewriteRule ^(.*)$ http://queness.com/$1 [L,R=301]

5. Custom Error page

Create a custom error page for each of the error codes.

ErrorDocument 401 /error/401.php
ErrorDocument 403 /error/403.php
ErrorDocument 404 /error/404.php
ErrorDocument 500 /error/500.php

6. Compress files

Optimize your website loading time by compressing files into smaller size.

# compress text, html, javascript, css, xml:
AddOutputFilterByType DEFLATE text/plain
AddOutputFilterByType DEFLATE text/html
AddOutputFilterByType DEFLATE text/xml
AddOutputFilterByType DEFLATE text/css
AddOutputFilterByType DEFLATE application/xml
AddOutputFilterByType DEFLATE application/xhtml+xml
AddOutputFilterByType DEFLATE application/rss+xml
AddOutputFilterByType DEFLATE application/javascript
AddOutputFilterByType DEFLATE application/x-javascript

7. Cache files

File caching is another famous approach in optimizing website loading time


Header set Cache-Control "max-age=2592000"

8. Disable caching for certain file type

Well, in the other hand, you can disable caching for certain file type.

# explicitly disable caching for scripts and other dynamic files

Header unset Cache-Control

Security

The following htaccess code will able to enhance the security level of your webserver. Hotlinking protection is pretty useful to avoid other people using images that stored in your server.

1. Hotlinking protection with .htaccess

Hate it when people stealing bandwidth from your website by using images that are hosted in your web server? Use this, you will able to prevent it from happening.

RewriteBase /
RewriteCond %{HTTP_REFERER} !^$
RewriteCond %{HTTP_REFERER} !^http://(www.)?queness.com/.*$ [NC]
RewriteRule .(gif|jpg|swf|flv|png)$ /feed/ [R=302,L]

2. Prevent hacks

If you want to increase the security level of your website, you can chuck these few lines of codes to prevent some common hacking techniques by detecting malicious URL patterns.

RewriteEngine On

# proc/self/environ? no way!
RewriteCond %{QUERY_STRING} proc/self/environ [OR]

# Block out any script trying to set a mosConfig value through the URL
RewriteCond %{QUERY_STRING} mosConfig_[a-zA-Z_]{1,21}(=|\%3D) [OR]

# Block out any script trying to base64_encode crap to send via URL
RewriteCond %{QUERY_STRING} base64_encode.*(.*) [OR]

# Block out any script that includes a