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From Patricia Shanahan <p...@acm.org>
Subject Re: datastructure classes
Date Sat, 18 Dec 2010 00:03:57 GMT
On 12/17/2010 8:00 AM, Gregg Wonderly wrote:
...
> One of the primary issues with bandwidth through any system is latency.
> While multiprocessor/multi-core and distributed computing can provide
> huge bandwidth possibilities, the underlying issue is per transaction
> latency.
>
> If you look simply, at the JDBC model for example, the act of converting
> the JDBC activities to network traffic and back (marshal/unmarshal) is
> one of the primary "time consuming operations". When you add onto that
> other overhead associated with how each database authenticates and
> manages its "network" traffic. I have no exact numbers to demonstrate
> this, but it is something which I have very long experience dealing
> with, over the years, with my broker (built before JMS existed) and
> catching up 100's of thousands of transactions into databases which have
> gone down for maintenance.
>
> JDBC only allows one transaction per connection, so you have context
> overhead involved there. With each transaction coming across a separate
> TNS-Listener process in oracle, you have OS context switching issues
> that inject latency.
>
> Overall, the bandwidth can be very large, but the per transaction
> latency is probably the biggest reason that SQL databases are not always
> the best choice for some types of performance needs.

Thanks. It's very useful to know specific gotchas with a given 
implementation strategy.

Patricia

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