Re: Two academic questions

On Tuesday, February 1, 2022, Дмитрий Иванов <firstdismay(at)gmail(dot)com> wrote:

> ср, 2 февр. 2022 г. в 09:19, David G. Johnston <david(dot)g(dot)johnston(at)gmail(dot)com
> >:
>
>> On Tue, Feb 1, 2022 at 8:15 PM Дмитрий Иванов <firstdismay(at)gmail(dot)com>
>> wrote:
>>
>>> Why are COLUMN GENERATED ALWAYS AS called "methods" and singled out as a
>>> separate field type?
>>>
>>
>> This sounds like you are describing something written. Can you provide a
>> link to where that is?
>>
>> It is possible to give a link, but it would require authorization:
>>>
>> 
> Here are the contents of the topic:
>
> DEFAULT VALUE <> GENERATED ALWAYS AS STORED
> the DEFAULT value is not recalculated when the reference column are
> changed. is not an identical construction GENERATED ALWAYS AS STORED
>
> *reply:*
> They are in a separate list “Methods”.
> This approach was used for other databases *long before* generated
> columns were implemented in PostgreSQL.
> ====================
>
>
It has to do with the syntax of generated and that you can generate data
in different ways. Calling those ways “methods” seems reasonable.

>
>>
>> Which community? There are many ways in which a "data schema [can be]
>> presented as data". In PostgreSQL there is only a single source of truth
>> for what the data schema is - the "System Catalogs" [1]. Those tables are
>> made available to the user in the pg_catalog schema.
>>
>> I came across a long acronym defining the name of the approach, then I
>> decided that to come up with something fundamentally new is difficult
>> enough. That everything already has a formal name. But I can't find it
>> anymore. I need it to position my solution.
>>
> Shema - shema
> Table Entity
> id | propery1| property2| property3
>
> Shema-data
>
> Table Entity
> id| name
>
> Table Property Entity
> id | id_entity | name| val
>

The Shema-data thing is called the Boogyman pattern because teachers use it
to scare students and illustrate what not to do when designing a data
model. You can also find it abbreviated “EAV anti-pattern” where EAV
stands for entity-attribute-value.

David J.