http://ayende.com/Blog/archive/2008/06/06/Scratching-an-itch-NMemcached.aspx
http://www.codeproject.com/KB/aspnet/memcached_aspnet.aspx
http://maxi326.wordpress.com/2009/11/02/use-memcached-in-net-application-with-linq/
http://zvolkov.com/blog/post/2009/06/18/Using-MemCached-with-NHibernate.aspx
http://latebound.blogspot.com/2008/10/using-memcached-from-c.html
http://www.codeplex.com/memcachedproviders
http://code.google.com/p/beitmemcached/
http://sourceforge.net/projects/memcacheddotnet/
http://www.codeplex.com/EnyimMemcached/
and the list go on...

What is MemCached? To put this in simple term, it's a cache store / hash table, where you can store almost everything, like objects, on it. Basically, it's very useful since there are parts where you don't want to cache your whole webpage but you just want to cache your object which you finished process or pulled out from database. It can save you hundreds of ms query time, server loads, and process time, which is very very very useful.

There are some downside if you run Memcached on Windows, the latest update for Memcached for windows that i can found is 1.2.5 I found a latest version here: 1.4.4, and the lates for linux is 1.4.4 (at the time I write this post). There are some solution for this problem. By using another computer/server installed as linux, you can solely run Memcached for cache purpose on multiple server. If you are not having more than 1 server, then just fall back to use System.Web.Cache since it's quite good for production already. You can also try out Velocity, which currently on it's CTP and I am not sure about whether Microsoft going to charge users for this.

I suggest you use MemCached Provider, it's the simplest to implement memcached in asp.net mvc, the following web.config instruction provided by MemCached Provider

Open Web.config file and add the following section to configSections tag

<section name="cacheProvider"
type="MemcachedProviders.Cache.CacheProviderSection, MemcachedProviders"
allowDefinition="MachineToApplication" restartOnExternalChanges="true"/>
<sectiongroup name="enyim.com">
<section name="memcached"
type="Enyim.Caching.Configuration.MemcachedClientSection, Enyim.Caching" />
</sectiongroup>
<section name="log4net" type="log4net.Config.Log4NetConfigurationSectionHandler,log4net"/>

Add the following section to configure Enyim’s client to point to Memcached servers

<enyim .com>
<memcached>
<servers>
<!-- put your own server(s) here-->
<add address="127.0.0.1" port="11211" />
</servers>
<socketpool minPoolSize="10" maxPoolSize="100"
connectionTimeout="00:00:10" deadTimeout="00:02:00" />
</memcached>
</enyim>

Add the following section to configure Memcached Cache Provider. keySuffix attribute allows for adding suffix to cache provider keys in order to simulate namespaces.

<cacheprovider defaultProvider="MemcachedCacheProvider">
<providers>
<add name="MemcachedCacheProvider"
type="MemcachedProviders.Cache.MemcachedCacheProvider, MemcachedProviders"
keySuffix="_MySuffix_" defaultExpireTime="2000"/>
</providers>
</cacheprovider>

Add following section to configure log4net

<log4net>
<!-- Define some output appenders -->
<appender name="ConsoleAppender" type="log4net.Appender.ConsoleAppender">
<layout type="log4net.Layout.PatternLayout">
<conversionpattern value="%date [%thread] %-5level %logger [%property{NDC}]
- %message%newline" />
</layout>
</appender>
<!--<threshold value="OFF" />-->
<!-- Setup the root category, add the appenders and set the default priority -->
<root>
<priority value="WARN"/>
<appender -ref ref="ConsoleAppender">
<filter type="log4net.Filter.LevelRangeFilter">
<levelmin value="WARN"/>
<levelmax value="FATAL"/>
</filter>
</appender>
</root>
</log4net>

Provided you include all the reference libraries, for example, this is my category controller, which will cache the object if it's not existed in the MemCached's memory.

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        public ActionResult Category()
        {
            var returnObj = DistCache.Get<list <CategoryObject>>("fullCatListObject");
            if (returnObj == null)
            {
                P015.Modules.Categories.Categories _cat = new P015.Modules.Categories.Categories();
                returnObj = _cat.getCatObject();
                DistCache.Add("fullCatListObject", returnObj, new TimeSpan(29, 0, 0, 0));
            }
            return View(returnObj);
        }
</list>

One thing you need to remember when using this library is to have all your objects that you want to save in memcached serialized. For example, this is my CategoryObject class use for the above example:

CategoryObject.cs

    [Serializable]
    public class CategoryObject
    {
        public string CAT_NAME { get; set; }
        public int CAT_ID { get; set; }
        public int LEVEL { get; set; }
    }

In case you are using Linq, or more specific, linq to sql, you can open your DBML file in design mode, change the Serialize Mode option to Unidirectional.

This works for me, so it should works for you too. Enjoy

You can use this piece of code in anywhere of your code where you want to cache any object.
(Notice: this code was used in a controller, so I used HttpContext.Cache. But if you use else where that make this code not working, try HttpContext.Current.Cache)

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            if (HttpContext.Cache["ObjName"] != null)
            {
                link = (string)HttpContext.Cache["ObjName"];
                return link;
            }
            else
            {
                HttpContext.Cache.Add("ObjName", link, null, System.Web.Caching.Cache.NoAbsoluteExpiration, new TimeSpan(30, 0, 0, 0, 0), System.Web.Caching.CacheItemPriority.High, null);
                return link;
            }

What it did was to check if the ObjName exist in the context, if not, create one and dump the data into it. Remember when you call back from HttpContext, it's an object so you always need a cast. If you don't know about argument, let the intellisense do the work for you.

Time to exand further about the topic: HttpContext.Cache.Add

My N+1 query was look like this:

SELECT * FROM Image WHERE IMG_ID = 1
SELECT * FROM Image WHERE IMG_ID = 3
SELECT * FROM Image WHERE IMG_ID = 7
SELECT * FROM Image WHERE IMG_ID = 9

however, later i found out a way to solve this by using "Contains" from IList to query "WHERE IN(x,x,x)".

Here is one function in my Repository:

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public List<Image> Images(IList<int> idList)
{
     return (from d in _db.Images
               .Where<Image>(d => idList.Contains<int>(d.IMG_ID))
               select d).ToList<Image>();
}

or better:

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 return _db.Images.Where<Image>(x => idList.Contains<int>(x.IMG_ID)).ToList<Image>();

these will output:

SELECT * FROM Image WHERE IMG_ID IN(1,3,7,9)