openstack team mailing list archive

[Nick Barcet <nick.barcet@xxxxxxxxxxxxx>]

> On Tue, May 15, 2012 at 10:26 AM, Doug Hellmann
> <doug.hellmann@xxxxxxxxxxxxx <mailto:doug.hellmann@xxxxxxxxxxxxx>> wrote:
> 
> 
> 
>     On Tue, May 15, 2012 at 8:21 AM, Julien Danjou
>     <julien.danjou@xxxxxxxxxxxx <mailto:julien.danjou@xxxxxxxxxxxx>> wrote:
> 
>         On Tue, May 15 2012, Loic Dachary wrote:
> 
>         > On 05/15/2012 12:05 PM, Julien Danjou wrote:
>         >>
>         >> OTOH I find the metadata proposal in another table too much
>         >> complicated. Why not storing what metadata in the
>         meter.payload field
>         >> in the same table (e.g. as a JSON string)?
>         > I would be much simpler to store the metadata in the
>         resource_id field
>         > which could be renamed into resource field.
> 
>         That'd be even more radical.
> 
> 
>     I like it because it would simplify the messaging. We can leave the
>     storage optimization question to the daemon that stores the data.
>
>         > Instead of resource_id=134123 we could have resource={ 'id':
>         134123,
>         > 'name': 'foobar', 'flavor': 'm1.small' etc.. } There would be
>         no need
>         > for versioning, format, separate table, etc. etc. The only
>         convention
>         > would be that it's a hash with at least one field : the id of the
>         > resource. The rest is metadata.
>         >
>         > It will use a lot of disk space with highly redundant information.
> 
>         Ok, so the current proposal is just early optimization, as I
>         understood.
> 
>         If you want to optimize the storage, why not use resource_id as a
>         foreign key to the metatable table which would contains unique
>         records
>         of metadata?
> 
>         That would allow to store identical metadata once (and therefore
>         optimize space) and will be much simpler. There would not be any
>         need of
>         version, timestamp, or whatever on metadata.

I fully second Julien's analysis regarding the storage of metadata in a
separate table.  We are overly complicating the schema for the sole
purpose of resource optimization.  In fact, the current metadata table
seems to be defining 5 fields where only one constitutes some valid
content we would like to extract at some point, the rest existing only
for relational or versioning purposes.  A bit of an overkill, it seems.

I would not recommend however to overcharge a field that can be used as
a key value for searches (resource_id) to store additional data, as it
would block us to search on that key easily.  Why mot just extend the
meter schema to add a metadata field, which can use the proposed JSON
format?

Nick

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