maria-discuss team mailing list archive

[Henrik Ingo <henrik.ingo@xxxxxxxxxxxxx>]

On Tue, Apr 5, 2011 at 5:50 AM, Arjen Lentz <arjen@xxxxxxxxxxxxx> wrote:
> On 04/04/2011, at 11:55 PM, MARK CALLAGHAN wrote:
>>
>> And then because this is Sun CoolThread hardware, each connection runs
>> on really, really slow CPUs. And 48 threads running concurrently will
>> get a lot of mutex contention from MySQL so maybe running 4 copies of
>> mysqld with each instance locked down to 12 CoolThread CPUs will help.
>
>
> Yea we look at this a few years back and found that MySQL could not really
> make effective use of this CPU/thread design at that stage.
>
> One potentially useful avenue was the addition of partitioning to 5.1, it
> was intended in part as a precursor to parallel query processing, for
> instance have one thread per partition resolving part of a query. This
> together with the disconnect between connections and threads
> (pool-of-threads etc) would enable this.
>
> Not having looked at the partitioning code, I don't know how much of a leap
> this would be, architecturally.

Stephane (now at SkySQL) told me he had used Spider engine as a hack
to get parallel query processing across partitions. Ie you can use
spider even if you have just one physical host, and it will process
the query against each partition in parallel.

henrik

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