Victor.Duchovnimorganstanley.com
Date: Wed Jun 11 2003 - 16:18:39 CDT

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On Wed, 11 Jun 2003, Leandro Santi wrote:

> On Wed, Jun 11, 2003, Wietse Venema wrote:
> > Leandro Santi:
> > > Oh. But... what about the proxymap? If someone uses the proxymap as a way
> > > to save lots of MySQL connections, then the coin method can have somewhat
> > > poor fairness performance (because the number of processes won't be
> > > always high enough -statistically speaking, of course-).
> >
> > If you have only a few connections, who cares? Load balancing
> > is an issue only when you have enough load to begin with.
>
> With the proxymap one could have relatively few instances (say, 5) of it,
> so the number of connections will be low as well, but that does not
> directly imply low load. Correct me if I'm wrong, but AFAIK multi server
> processes like the proxymap don't enforce max_use strictly. This isn't good
> for the coin solution.
>

Wietse's point is that lack of load-balancing is not important unless it
leads to query latency. Query latency will cause the proxymap service to
be busy and therefor more instances will be spawned. If 5 proxymap
instances are all it takes to handle the load, the load-balancing is
adequate.

So it is unlikely that assymetric loading will make any one of the MySQL
servers so tardy as to be unusable for other applications, there may also
be connection setup costs in MySQL that you are not measuring.

Try it with statistical load balancing first, and if evidence emerges that
this is not good enough, solve the more complex problem later.

--
        Viktor.

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