[Engine-devel] What type of DB inheritance to use?

[Itamar Heim]

On 05/12/2013 03:16 PM, Mike Kolesnik wrote:
> ----- Original Message -----
>> On 05/12/2013 12:42 PM, Mike Kolesnik wrote:
>>> Hi All,
>>>
>>> I would like to have your opinions on which inheritance type to use in
>>> the DB.
>>> We are adding an "external provider" entity to the system which will be
>>> able to provide various resources (networks, hosts, etc).
>>>
>>> These providers will be distinguishable by "type".
>>> The basic definition of a provider contains:
>>>
>>>    * name
>>>    * description
>>>    * url
>>>    * type
>>>
>>> Some providers might need additional properties such as:
>>>
>>>    * user
>>>    * password
>>
>> what type of provider won't require authentication?
>
> Quantum provider in the 1st implementation will not require these fields.
> It will eventually require some sort of authentication, but not necessarily
> these fields, or only these fields.

I'm not talking about a POC.
unless we pass through credentials of users for some actions, how do you 
use a provider without user/password (or client cert, etc. - i.e., all 
authentication methods are usually similar on the info you need to persist)?

>
>>
>>>
>>> In Java this is easily represented by inheritance.
>>>
>>> In the DB however, there are 3 approaches that we can take:
>>>
>>>   1. No inheritance.
>>>      This means that each type will wit in his own table, with no
>>>      relation or re-use.
>>>   2. Single table inheritance.
>>>      All types sit in a single table, and each has his corresponding
>>>      columns.
>>>   3. Multiple table inheritance.
>>>      Each type sists in his own table, where the PK is FK for the most
>>>      basic table (providers).
>>>
>>>
>>> Pros for each approach:
>>>
>>>   1. None that I can think of.
>>>   2. No joins:
>>>           Better performance
>>>           Easier for developer to see the DB info
>>>           Facilitate column reuse
>>>   3. Constraints can be set on each column
>>>
>>> Cons for each approach:
>>>
>>>   1. No reuse of DB entities + no compliance for column types
>>>      Most cumbersome to query all providers
>>>   2. Can't put some constraints on non-base columns (esp. not null)
>>>   3. Joins are needed - opposite of the pros of 2.
>>>
>>>   From personal experience, I find #2 to be better and easier to work
>>> with & maintain.
>>>
>>> What are your thoughts?
>>>
>>> Regards,
>>> Mike
>>>
>>>
>>>
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>>>
>>
>>