Mnesia disk performance (was RE: multi-attribute mnesia indexes?)
Tue Jan 2 22:54:31 CET 2001
Andi Kleen <> scrawled:
> On Tue, Jan 02, 2001 at 03:49:16PM -0500, Shawn Pearce wrote:
> > Oracle does this with their database and it is a big performance
> > booster. The other thing they do is allow a table to be striped
> > across multiple disks by making a table exist in multiple file system
> > files at once. (They stripe disk allocations across the files.) This
> > does help to manage larger tables as well.
> Near all modern OS can do that themselves using volume managers and software
> RAID -- it would probably be a waste of time to implement it in Mnesia too.
This is true, and I agree. However, it does allow Oracle to easily
handle >2GB datafiles on Unixes that cannot deal with it. It also
lets you stick to 32 bit file offsets by adding a file number
Keep in mind its nice to be able to split backups onto tapes by
designing the database datafiles such that one data file fits onto a
tape. Or a cluster of datafiles fits onto a tape. What if we have a
100GB database, how do we dump it onto 20GB tapes?? If its one huge
file, its harder to dump than if its a collection of 10GB files. Or
1GB files that can be put on tape at 20 (or 19) files at a time.
But striping may be out of the question. Maybe its just a linear
Anyway, just a thought on top of my other comments with Mnesia.
``If this had been a real
life, you would have
on where to go and what
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