Re: proposal: schema variables

ne 10. 11. 2024 v 18:51 odesílatel Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>
napsal:

>
>
> ne 10. 11. 2024 v 17:19 odesílatel Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>
> napsal:
>
>>
>>
>> ne 10. 11. 2024 v 16:24 odesílatel Dmitry Dolgov <9erthalion6(at)gmail(dot)com>
>> napsal:
>>
>>> Hi folks,
>>>
>>> Thanks for continuing this work. As a side note, I would like to mention
>>> how strange the situation in this CF item is. If I understand correctly,
>>> there are two hackers threads discussing the same patch, with recent
>>> patches posted in both of them. This is obviously confusing, e.g. the
>>> main concern from another thread, about names clashing, wasn't even
>>> mentioned in this one. Is it possible to reconcile development in one
>>> thread?
>>>
>>
>> This is probably my error. I don't try to organize threads, just I'll try
>> to reply in the thread where I got a question.
>>
>
> I thought a lot of time about better solutions for identifier collisions
> and I really don't think so there is some consistent user friendly syntax.
> Personally I think there is an easy already implemented solution -
> convention - just use a dedicated schema for variables and this schema
> should not be in the search path. Or use secondary convention - like using
> prefix "__" for session variables. Common convention is using "_" for
> PLpgSQL variables. I searched how this issue is solved in other databases,
> or in standard, and I found nothing special. The Oracle and SQL/PSM has a
> concept of visibility - the variables are not visible outside packages or
> modules, but Postgres has nothing similar. It can be emulated by a
> dedicated schema without inserting a search path, but it is less strong.
>

There can be more collisions in Oracle, because the functions without
arguments don't need parentheses. Postgres is safer, because this syntax is
not allowed.

>
> I think we can introduce an alternative syntax, that will not be user
> friendly or readable friendly, but it can be without collisions - or can
> decrease possible risks.
>
> It is nothing new - SQL does it with old, "new" syntax of inner joins, or
> in Postgres we can
>
> where salary < 40000
>
> or
>
> where pg_catalog.int4lt(salary, 40000);
>
>
> or some like we use for operators OPERATOR(*schema*.*operatorname*)
>
> So introducing VARIABLE(schema.variablename) syntax as an alternative
> syntax for accessing variables I really like. I strongly prefer to use this
> as only alternative (secondary) syntax, because I don't think it is
> friendly syntax or writing friendly, but it is safe, and I can imagine
> tools that can replace generic syntax to this special, or that detects
> generic syntax and shows some warning. Then users can choose what they
> prefer. Two syntaxes - generic and special can be good enough for all - and
> this can be perfectly consistent with current Postgres.
>
> Regards
>
> Pavel
>
>
>> Regards
>>
>> Pavel
>>
>>
>