We don't need to do any advanced querying or search during the real-time bidding request process - it's just raw lookup based on "cookie ids" (we're not always

We don't need to do any advanced querying or search during the real-time bidding request process - it's just raw lookup based on "cookie ids" (we're not always using cookies). Simplicity of operations, horizontal scaleability and consistent, predictable performance are the key characteristics required. Other parts of the system have very different requirements and yes, we are considering graph oriented databases for our cross-device analytics product.