Should i implement my key/value system in memory or in MS SQL or 3rd party?

I think I've done enough research to know that i want to go with a NOsql key/value route. I've read up as much as i can and have the following questions still:

• should i go with something like amazon simpledb, google big table or microsoft azure's solution? (note i'm a .NET site)

• why not just simply create an in memory hash开发者_JAVA百科table of keys/objects (assuming memory is abundant enough to story everything)?

• how about creating a table in my SQL server with two columns, one a key and one a value. the key is the primary key and the value is a string of whatever i want. i'll have to pull the string out and parse it into something meaningful though.

• shoudl i go with something like neo4j graph database?

it's unclear to me which path i should take.

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My feeling is if you really want a key value type system pick a noSQl database. Relational databases do not do a good job of handling key-value type queries and they are real performance killers in a relational database. IF you are going this route, use the right tool for it.