How to install MongoDB on CentOS 5.4 / RHEL5 and interface with PHP 5

2010/05/11 by admin in NoSQL | 5 Comments

If you’ve been reading up on the various NoSQL offerings and have wanted to try out one but don’t know how to get started, this is one of the easiest ways. I chose MongoDB for this example because I’m going to start using it for a project that needs features that MySQL isn’t as fast at: namely denormalized data with billions of rows. MongoDB has plenty of drivers for other scripting and high-level languages but I’ll focus on the PHP driver today. If there is interest I can do a write up on Python usage later. This example is limited to CentOS, Fedora, and Redhat 5 servers that use the yum package management system. For more information you can reference their download page: http://www.mongodb.org/display/DOCS/Downloads

First install the prerequisites:

  • sudo yum install gcc php php-pear

Then install the mogo php extension via pecl and add the extension to the ini file. (Increase the php.ini memory_limit to 32M if necessary). Then we restart apache to have the extension loaded. You can check your extensions via the phpinfo(); command in php.

  • sudo pecl install mongo
  • sudo echo “extension=mongo.so” >> /etc/php.ini
  • sudo /etc/init.d/httpd restart

For the last part we add the yum repo and get the actual MongoDB server and client installed

  • cd /etc/yum.repos.d
  • sudo emacs mongodb.10gen.repo
  • paste in the following. This uses the repo for 64bit servers. See their download page for other architecture repo settings.

    • [10gen]
    name=10gen Repository
    baseurl=http://downloads.mongodb.org/distros/centos/5.4/os/x86_64/
    gpgcheck=0

  • sudo yum install mongo-stable-server
  • sudo /etc/init.d/monod start
  • chkconfig mongod on

That’s it, you’re ready to start using Mongo! You can check the logfile to make sure things are running smoothly: “sudo cat /var/log/mongo/mongod.log”

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Event based programming vs threading by Rob von Behren, Jeremy Condit and Eric Brewer

2010/04/15 by admin in Programming | 1 Comment

Saw this interesting paper about highly concurrent programming methods and figured the word should be spread! It’s not new material but it’s a good read. See the full article here: http://www.usenix.org/events/hotos03/tech/full_papers/vonbehren/vonbehren_html/

“Highly concurrent applications such as Internet servers and transaction processing databases present a number of challenges to application designers. First, handling large numbers of concurrent tasks requires the use of scalable data structures. Second, these systems typically operate near maximum capacity, which creates resource contention and high sensitivity to scheduling decisions; overload must be handled with care to avoid thrashing. Finally, race conditions and subtle corner cases are common, which makes debugging and code maintenance difficult.

Threaded servers have historically failed to meet these challenges, leading many researchers to conclude that event-based programming is the best (or even only) way to achieve high performance in highly concurrent applications. “

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