On Tue, Jan 30, 2001 at 01:13:43PM -0800, Jeremy D. Zawodny wrote:
> On Tue, Jan 30, 2001 at 05:08:46PM +0000, Tim Bunce wrote:
> > On Tue, Jan 30, 2001 at 10:57:16PM +0800, Sam Wong wrote:
> > > >
> > > > So why isn't the --with-raid option set in the binary download version?
> > >
> > > The file will be bigger and slower in result
> >
> > I doubt it would be significantly bigger. I believe --with-raid
> > support is a very small and simple layer between mysqld and the file
> > i/o system calls.
>
> At the open source database summit, I asked Monty why it wasn't
> enabled in the binaries they provide, and he said that it was for
> performance reasons. On each table open, MySQL has to see if it is a
> RAID table and do a bit of extra work.
Why not determine it by checking only if the open of the non-raid fail
failed? That way there'd be no penalty for those not using the raid
feature.
> > I'm not sure what you mean by "slower in result".
>
> He has estimated it as a performance hit of a "few percent", but if
> your tables stay open (because you don't have many, or you have a
> good-sized table cache) it really shouldn't be an issue.
I can't see where a "few percent" hit would come from unless tables
were being opened at the rate of many per second. Anyone smart enough
to be using the raid feature would also know how to tune mysql to keep
the files open. Those not using the feature should see no hit.
Anyway, even if there is a hit, why not allow a runtime config option
to disable the raid feature? Checking a global in C is basically free.
> He said that MaxSQL would have many of the compile-time options
> enabled for folks who still wanted to use a binary release. But it
> doesn't appear to have materialized...
I wish it would.
Monty, can you give us an update?
Tim.
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