MemSQL vs. MongoDB

	MemSQL	MongoDB
Category	Database	Database, Data Storage
Preference	75% votesvotes	25% votesvotes
Website	www.​memsql.​com	www.​mongodb.​org
License	Proprietary	AGPLv3
Design
Database model	Relational, Distributed data structure	Document-oriented, Schema-less, NoSQL
Data storage	Volatile memory, File System	Volatile memory, File System
Embeddable	Yes	Yes
Features
Query language	SQL	API calls, JavaScript, REST
Data types	All MySQL, JSON, BLOB	JSON
Conditional entry updates	Yes	Yes
Map and reduce	Yes	Yes
Unicode	Yes	Yes
TTL for entries	No	Yes
Compression	Yes	Yes
Integrity
Integrity model	ACID, MVCC	BASE
Atomicity	Yes	Conditional
Consistency	Yes	Yes
Isolation	Yes	Yes
Durability (data storage)	Yes	Yes
Transactions	Yes	No
Referential integrity	Yes	No
Revision control	Yes	No
Locking model	Lock Free Model, MVCC	Optimistic Locking, Lock on write
Indexing
Secondary Indexes	Yes	Yes
Composite keys	Yes	Yes
Full text search	No	Yes
Geospatial Indexes	Yes	Yes
Graph support	No	No
Graph type	Oriented graph	?
Distribution
Horizontal scalable	Yes	Yes
Replication	Yes	Yes
Replication mode	Master-Slave Replication	Master-Slave-Replica Replication
Sharding	Yes	Yes
Shared nothing architecture	Yes	Yes
Restrictions
Value size max.	1 000 EB	16 MB
System requirements
Operating system	Linux, Amazon EC2	Linux, Windows, Mac OS X
Native driver	C, C++, php, Java, Python, Objective-C, Ruby, Go	Java, php, Ruby, C#, Python, JavaScript, Haskell, Perl, C++, Erlang, Scala, C, Go
Memory recommended	8 GB	?
Memory minimum	8 GB	?
Architecture
Programming language	C++	C++
More
Description	In-Memory Database used for real-time analytics.	Document Oriented Database
Multi-user system	Yes	Yes
Accelerometer sensor	No	?
Price rating	●●●○○	●●●●●
Software distribution	Package management system	Tarball, Ubuntu Software Center, Package management system, Windows Installer
Object-Relational Mapping (ORM)	Yes	Yes
Release Date	18ᵗʰ June 2012	March 2009
Documentation level	●●●●○	●●●●●
Distributed Counter	Yes	?
Free to use	Yes	Yes
Active	Yes	Yes
Database Connection Pooling	Yes	Yes
Real time analytics	Yes	Yes
2 Letter Country Code	US	?
Cloud platform support	Amazon EC2	Heroku, CloudBee, Bluemix, Amazon EC2, SoftLayer
Online backup	Yes	Yes
Function Based Index	Yes	No
Log	Yes	Yes
Download	www.​memsql.​com/​#download	mongodb.​org/​downloads
Backup functionality	Good	Good
Query Cache	Yes	Yes
Ease of use	●●●●○	●●●●●
Free for commercial use	No	Yes
Sorts	Yes	Yes
Perfomance	●●●●○	●●●●○
Materialized Views	No	No
Spring Data Support	Yes	Yes
JSON	Yes	Yes
Stored Procedure	No	Yes
Concurrency	Yes	?
Multi-statement Transactions	Yes	Yes
Columner	Yes	?
Brand	?	MongoDB Inc
Extension/Plug-in	?	Yes
Database	?	MongoDB
Standard compliance	?	No
RESTful	?	Conditional
Lines of code	?	617 k
Community Driven	?	Good
Web interface	?	Yes
Data encryption	?	Conditional
Admin Generator	?	Yes
Partial Index	?	No
Key length max	?	128
Implementation flexibility	(0% global votes)	(48% global votes)
In-Place Update	?	Yes
Capped Collections	?	Yes
Tuneable write concerns	?	Yes
Read preferences	?	Yes
Open Source	?	Yes
Op/s	?	5 000
Triggers	?	No
Pause Test	?	Yes
Cross Domain Testing	?	No
Pipeline Aggregation	?	Yes
Geospatial	?	Yes
Server Side Java Script	?	Yes
Flexible Table(Schema)	?	Yes
Geo-distributed	?	Yes
Max rows in query result	?	1 000
Re-Reduce	?	Yes
Clustering over WAN	?	Yes
Fully Distributed	?	Yes
Auto-Sharding	?	Yes
memcached protocol	?	No
Monitoring UI	?	Yes
Recursive queries	?	No
Network datatype	?	No
Windowed aggregate	?	No
CLI`	?	Yes

This table is based on the vsChart comparison MemSQL vs. MongoDB comparison | vsChart.com, which is released under the Creative Commons Attribution-Share-Alike License 3.0.

wget and curl 指令

wget 指令介紹
curl 指令介紹
使用curl 批次下載

Linux 圖片轉檔指令

convert beach.gif beach.pnm


NAME
convert - convert an image or sequence of images

SYNOPSIS
convert [ options ... ] input_file output_file

DESCRIPTION
Convert converts an input file using one image format to an output file with a differing image format. In addition, various types of image processing can be performed on the converted image during the conversion process. Convert recognizes the image formats listed in ImageMagick.

Install Flask on CentOS 7.0

1. Install pip on CentOS 7.0

## First install the EPEL repo as per your Operating system version and architecture.
rpm -ivh http://mirror01.idc.hinet.net/EPEL/7/x86_64/e/epel-release-7-1.noarch.rpm
yum install -y python-pip

2. Install Flask

pip install Flask

## Test
vi hello.py

from flask import Flaskapp = Flask(__name__)
@app.route("/")def hello():    return "Hello World!"
if __name__ == "__main__":    app.run()

## Verify
python hello.py

* Running on http://0.0.0.0:80/

Python: ConfigParser

[core]
cmd = /usr/bin/vim

[mod]
safe_edit = yes
time_interval = 20

python 程式如下：

#!/usr/bin/python
from ConfigParser import SafeConfigParser
parser = SafeConfigParser()
parser.read('test.conf')

#傳回字串 /usr/bin/vim
parser.get('core', 'cmd')

#傳回 boolean 值 True
parser.getboolean('mod', 'safe_edit')

#傳回整數值 20
parser.getint('mod', 'time_interval')

references:
http://williewu.blogspot.tw/2007/10/python-configparser.html
https://wiki.python.org/moin/ConfigParserExamples
https://docs.python.org/2.6/library/configparser.html