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Development & Deployment of Multiplayer Online Games, page 4:

OLTP DB Optimizations 101 – Thinking in Terms of Execution Plans

Quote: “to realize how our queries are working – we need to start thinking in terms of so-called “execution plans”.”
Another Quote: “it can be faster to use Table Scan rather than Index-Scan+fetch over such a low-selectivity index”
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Help Desk Software for MOGs

Quote: “for MOGs, support becomes one of the very important parts of the picture, often on par with Content and Graphics.”
Another Quote: “the quality of support when using synchronous support methods such as live chat/phone support tends to be significantly worse compared to asynchronous support such as e-mails/tickets”
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Scaling Stateful Objects

Quote: “it is DB which is usually The Bottleneck™ – it means that we’re saving this enormous amount of load, exactly where it really matters.”
Another Quote: “as discussed above, the real-world task is always about scaling the whole system, including database; and in this regard Stateless-App-based systems exhibit significant problems.”
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Scalability for MOGs

Quote: “Whenever Game Event is interrupted for significant time, as a rule of thumb it is better to roll back the interrupted Game Event rather than trying to restore the exact Game World State in the middle of the Game Event.”
Another Quote: “Just like Scaling Up, improving performance doesn’t provide infinite scalability. However, it happens that it is all about numbers.”
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