[openstack-dev] [all][keystone] Increase of USER_ID length maximum from 64 to 255

Sean Dague sean at dague.net
Sun Mar 2 12:16:07 UTC 2014

On 03/01/2014 08:00 PM, Clint Byrum wrote:
> Excerpts from Robert Collins's message of 2014-03-01 14:26:57 -0800:
>> On 1 March 2014 13:28, Clint Byrum <clint at fewbar.com> wrote:
>>> +1. A Keystone record belongs to Keystone, and it should have a Keystone
>>> ID. External records that are linked should be linked separately.
>>> It may not be obvious to everyone, but MySQL uses B-trees for indexes.
>>> B-trees cannot have variable-length keys.
>> Hmm, B-Trees and B+-Trees both can have variable length keys. I'll
>> accept an assertion that MySQL index B-trees cannot - but we should be
>> precise here, because its not a global limitation.
> Sorry, I misspoke, _InnoDB's_ b-tree's cannot have variable length keys.
> :-P

On a previous project we did a transition from varchar based UUID to
binary based UUID in MySQL. The micro benchmarks on joins got faster by
a factor of 10,000 (yes 10k). Granted, MySQL has evolved since then, and
this was a micro benchmark, however this is definitely work considering.


Sean Dague
Samsung Research America
sean at dague.net / sean.dague at samsung.com

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