Обсуждение: Difference between function and procedure?

Hi,

I'm diving more into depth of the features outside the typical table
stuff, which I usually need.

I wrote a trigger that fires a function written in PL/Python, both works
fine so far.

But as I browsed my database via pgAdmin3 I recognized that there is
also 'Procedures' under 'public' available, but empty yet. Trying to
create a procedure resulted in the same SQL statement like creating a
function (CREATE FUNCTION ...). I couldn't see any difference. Also
didn't find in the PostgreSQL manual if there is a difference between
functions and procedures. Are there any at all?

Anastasios

PS: Using PostgreSQL 8.1.3 on Windows XP development machine.

On 7/19/06, Anastasios Hatzis <ahatzis@gmx.net> wrote:
> Hi,
>
> I'm diving more into depth of the features outside the typical table
> stuff, which I usually need.
>
> I wrote a trigger that fires a function written in PL/Python, both works
> fine so far.
>
> But as I browsed my database via pgAdmin3 I recognized that there is
> also 'Procedures' under 'public' available, but empty yet. Trying to
> create a procedure resulted in the same SQL statement like creating a
> function (CREATE FUNCTION ...). I couldn't see any difference. Also
> didn't find in the PostgreSQL manual if there is a difference between
> functions and procedures. Are there any at all?

there are differences. PostgreSQL only really supports functions and
on the lists they are used interchangably.  on the -hacker list about
a year back there was a good discussion about implementing true SP and
why they would be needed.

mainly, SP are not externally transactional, making them useful for
maintenance type work, such as vacuum (cant be run from inside a
transaction) or multiple statement data load via 'copy' commands.

i thnk (not sure) that SP can not be inlined into queries like
functions.  this would be an important distinction.

merlin

Merlin Moncure wrote:
> there are differences. PostgreSQL only really supports functions and
> on the lists they are used interchangably.  on the -hacker list about
> a year back there was a good discussion about implementing true SP and
> why they would be needed.
>
> mainly, SP are not externally transactional, making them useful for
> maintenance type work, such as vacuum (cant be run from inside a
> transaction) or multiple statement data load via 'copy' commands.
>
> i thnk (not sure) that SP can not be inlined into queries like
> functions.  this would be an important distinction.
>
Merlin,

thank you for clarifying this. So, given your hint, I didn't miss SP
until now, but this will probably change in future. ;-)

Anastasios