[openstack-dev] [oslo][oslo.db] MySQL Cluster support
Octave J. Orgeron
octave.orgeron at oracle.com
Fri Feb 3 16:59:01 UTC 2017
Hi Mike,
Comments below..
Thanks,
Octave
On 2/3/2017 7:41 AM, Mike Bayer wrote:
>
>
> On 02/02/2017 05:28 PM, Octave J. Orgeron wrote:
>> That refers to the total length of the row. InnoDB has a limit of 65k
>> and NDB is limited to 14k.
>>
>> A simple example would be the volumes table in Cinder where the row
>> length goes beyond 14k. So in the IF logic block, I change columns types
>> that are vastly oversized such as status and attach_status, which by
>> default are 255 chars.
>
>
> let me give you a tip on IF blocks, that they are a bit of an
> anti-pattern. If you want a column type to do one thing in one case,
> and another in another case, create an object that does the thing you
> want:
>
>
> some_table = Table(
> 'some_table', metadata,
> Column('my_column', VARCHAR(255).with_variant(VARCHAR(50), 'ndb'))
> )
>
>
> I think we might want to look into creating a stub dialect called
> 'ndb' that subclasses mysql+pymysql. Treating ndb as a whole
> different database means there's no longer the need for a flag in
> oslo.db, the 'ndb' name would instead be interpreted as a new backend
> - the main thing would be ensuring all the mysql-appropriate hooks in
> oslo.db are also emitted for ndb, but this also gives us a way to pick
> and choose which hooks apply. It seems like there may be enough
> different about it to separate it at this level.
>
> Not sure if people on the list are seeing that we are simultaneously
> talking about getting rid of Postgresql in the efforts to support only
> "one database", while at the same time adding one that is in many ways
> a new database.
>
>
This is an interesting approach as it would significantly reduce the
amount of code in my patches today. Do you have any pointers on where
this should be implemented as a stub? Would we have to take different
approaches for SQL Alchemy vs. Alembic?
--
Oracle <http://www.oracle.com/>
Octave J. Orgeron | Sr. Principal Architect and Software Engineer
Oracle Linux OpenStack
Mobile: +1-720-616-1550 <tel:+17206161550>
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