Re: proposal: schema PL session variables

2016-02-09 20:55 GMT+01:00 David G. Johnston <david(dot)g(dot)johnston(at)gmail(dot)com>:

> On Tue, Feb 9, 2016 at 11:32 AM, Corey Huinker <corey(dot)huinker(at)gmail(dot)com>
> wrote:
>
>>
>> Oh, and I suggest we call them SESSION variables rather than SCHEMA
>> variables, to reinforce the idea of how long the values in the variables
>> live. A session variable is in a sense a 1x1 temp table, whose definition
>> persists across sessions but whose value does not.
>>
>> Of course, if they do persist across sessions, then yeah, SCHEMA makes
>> more sense. But every package variable in Oracle PL/SQL was initialized
>> when the package was first loaded into the session.
>>
>>
> ​The key distinction for SCHEMA was that all functions in the schema would
> be able to see them (and only those in the schema).
>
> I am a bit partial, with little deep thought, to the IMPORT mechanic.
> Changing them to actual session variables would be doable and you could
> allow for the IMPORT specification to use search_path or explicit means to
> locate said variables regardless of which schema​
>
> ​they exist in.
>

Very important part of my proposal is independence on search_path. With
search_path you have not any control over variable type, variable existence
- and there are possible lot of impacts on plan cache, behave. So I propose
SCHEMA VARIABLES with schema scope - and then search_path has zero effect
on the behave. It doesn't introduce new dependencies.

Pavel

>
> However, part of the goal is to blend into the broader database community
> and thus increase porting capabilities. I'm not sure how well this would
> help fulfill that goal.
>
> David J.
> ​
>
>