Re: Oracle Style packages on postgres

Jim C. Nasby wrote:

>I don't believe types allow for internal-only methods. I seem to recall
>other limitations on what types could do as opposed to packages. Of
>course, we need not restrict ourselves in such a manner.
>  
>
Do Oracle packages support internal only functions? If they do, then I 
agree, that's a feature that the SQL standard doesn't have.

>Types are not used nearly as much as packages (this is an issue if we
>care about enabling Oracle users to migrate).
>
>Types generally force you to use them in relation to some database
>object. Packages have no such restriction.
>  
>
If used as a package, i.e. only containing static methods, you don't 
need to use the type in relation to anything. It's simply a namespace. 
If used with a temporary table, you get a very neat, standardized, 
cross-language way of managing session data.

>Don't get me wrong, I think supporting more powerful types would be a
>welcome addition, but I don't think they can be as flexable as packages.
>  
>
I see this differently. A full implementation of the SQL-standard for 
UDT's will allow abstract types, inheritance, method overloading, etc. 
It quickly becomes far more flexible then Oracle packages. A full 
implementation is of course beyond the scope for what's needed to 
accommodate the needs of those who use packages but a simple 
implementation is extendable within the scope of the standard.

>The good news is that they should both be able to use the same
>underlying framework. Types are afterall just a specialized
>implementation of packages.
>  
>
Right. Given a good implementation of types, packages would be easy to 
implement. The other way around would not be possible. A package is a 
very restricted type that contains static methods only. Possibly with 
the extension of some kind of method/attribute visibility.

So do we need "internal only" functions although they are not covered by 
the SQL-standard? If the answer is no, then IMO we should follow the 
standard and use types, not packages. If the answer is yes, then the  
SQL-standard is not enough. Should we then use packages or simply 
introduce the keyword PRIVATE on methods of a type? Personally, I'd go 
for the latter and then, if necessary, build packages on top of that in 
for the benefit of Oracle users who wants to migrate. A fully fledged 
type system will ease Oracle migration too since Oracle already has this.

Regards,
Thomas Hallgren