Re: mutex contention for the query cache

[Mark Leith]

Brian Aker wrote:
> Hi!
>
> On Jul 3, 2008, at 2:05 PM, Sergei Golubchik wrote:
>
>> extent query cache so that Maria would use exact visibility rules and
>> maximize cache using - all transactions that could see the entry would
>> see it, those that couldn't - wouldn't.
>
> Well I will look forward to seeing how you solve that for Maria.
>
>> Query cache as it's done now is dirt cheap (concurrency can be fixed).
>
> I have some big doubts that this is the case. I think you will find 
> that the lock methods being deployed right now around RW are not going 
> to scale on any of the hardware we are seeing deployed. As is you will 
> find that the general rule of thumb today is to just get rid of it. 
> For anyone wanting to make use of the hardware that they are deploying 
> the only solution is to junk it.

I'm sorry, but the query cache *does* have it's uses in many *many* 
installations. Not everybody is a huge webscale shop on huge multi-core 
boxes.

The *correct* solution is to make it fully pluggable, and let people 
make their own choices on whether it fits their application architecture 
and environment or not.

Think about the little guys too, huh? They represent a good portion of 
our users and customers, and probably will for a good long while yet.

-- 
Mark Leith
MySQL Regional Support Manager, Americas
Sun Microsystems, Inc., http://www.sun.com/mysql/