Entries tagged memcached

Related tags: debian-administration, local-people, memcachedb, redis.

Cover your heart! Cover your heart!

Wednesday, 13 January 2010

I've long been a fan of Danga's Memcached, back in 2005 I wrote about it for the first time.

Recently I've been looking at the persistant version, memcachedb which is essentially a Berkeley Database using the memcached protocol as the transport layer. This allows you to get persistance for free, and means you can rely upon the content being present, rather than just hoping it will be there as an opportunistic cache.

However in this brave new world of nosql I've been mulling over different options for new projects / new toys. I have to say that memcachedb lost out for me, and that Redis is my preferred flavour of new hot.

Redis has a rich API allowing you to store interesting datatypes such as lists, and it allows both replication and distribution (neither of which I need just yet, but both are useful to have as options for the future).

The documentation is great including a well-documented Twitter clone, and the facilities that are available are a step up from memcached, albeit obvious extensions which you'd expect if you were doing interesting things.

The redis-server package is already part of Debian GNU/Linux, and creating .deb package of the Redis module was trivial.

So now that I'm familiar with it, what to use it for? Well I think the first thing will be the new 2010 Valentines site.

Over the years I've hosted several Livejournal Valentine sites, and this year is no different. (Why? I like matching people, and I like social stuff. This is why I did ctrl-alt-delete in the past, even if that failed it was a great learning experience and I'd do it again if I had the time/patience/more optimism).

So far the site only has a couple of users but I fully expect it to ramp up considerably before the magical day (ha!). In the past I've limited the lifetime of the site(s) from Feb 1st to Feb 14th and still managed to achieve 5000+ users. Right now I'm using flat files for storage specifically to avoid database-load issues (which caused me considerable pain one year).

I suspect the backend will be Redis-based in the very very near future, but in the meantime if you're open to amusement and use Livejournal then feel free to poke at it: ljvalentine.com.

ObFilm: Indiana Jones and the Temple of Doom

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Long journeys wear me out but

Tuesday, 22 May 2007

I was suprised to see Michal Čihař suggesting that memcached wasn't helping his site enough.

I've been a huge fan of Danga's Memcached for the past year or two. I'm using it very heavily upon the Debian Administration website, and also upon my new dating site.

There are, of course, issues with making sure you flush the cache when things are updated, but I've got a good pair of test suites for that now :)

With a nice singleton accessor I can use the code as easily as:

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sub recent_users
{
    my $cache   = Singleton::Memcache->instance();
    my $results = $cache->get( "recent_users" );
    return( $results ) if ( $results );

    # fetch from database
    
    $cache->set( "recent_users", $results );
    return( $results );
}

Obvious once you've done it a few times, but right now I can feel the difference if I disable the cache upon either of the sites. Page loadtime just drops.

I guess the effectiveness depends upon the site you're using, and how often things can be usefully cached. I know that for my uses I tend to have large items which would be expensive to fetch which occur on every page (such as "currently online users", or "recent weblogs".) That probably means I benefit more than others, still I've become so enamoured of the project I feel the need to pimp it a little!

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