From: | Thom Brown <thom(at)linux(dot)com> |
---|---|
To: | Merlin Moncure <mmoncure(at)gmail(dot)com> |
Cc: | Bruce Momjian <bruce(at)momjian(dot)us>, Josh Berkus <josh(at)agliodbs(dot)com>, pgsql-hackers(at)postgresql(dot)org |
Subject: | Re: "stored procedures" |
Date: | 2011-08-31 14:00:51 |
Message-ID: | CAA-aLv6b_4NUjQj-WtX_4bMeJtj_RSVjZVSwxYftOm8+81h95w@mail.gmail.com |
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Lists: | pgsql-hackers |
On 9 May 2011 20:52, Merlin Moncure <mmoncure(at)gmail(dot)com> wrote:
> On Mon, May 9, 2011 at 1:41 PM, Bruce Momjian <bruce(at)momjian(dot)us> wrote:
>> Josh Berkus wrote:
>>> Peter,
>>>
>>> > I would like to collect some specs on this feature. So does anyone have
>>> > links to documentation of existing implementations, or their own spec
>>> > writeup? A lot of people appear to have a very clear idea of this
>>> > concept in their own head, so let's start collecting those.
>>>
>>> Delta between SPs and Functions for PostgreSQL:
>>>
>>> * SPs are executed using CALL or EXECUTE, and not SELECT.
>>>
>>> * SPs do not return a value
>>> ** optional: SPs *may* have OUT parameters.
>>
>> [ Late reply.]
>>
>> What is it about stored procedures that would require it not to return a
>> value or use CALL? I am trying to understand what part of this is
>> "procedures" (doesn't return a values, we decided there isn't much value
>> for that syntax vs. functions), and anonymous transactions.
>
> FWICT the sql standard. The only summary of standard behaviors I can
> find outside of the standard itself is here:
> http://farrago.sourceforge.net/design/UserDefinedTypesAndRoutines.html.
> Peter's synopsis of how the standard works is murky at best and
> competing implementations are all over the place...SQL server's
> 'CALL' feature is basically what I personally would like to see. It
> would complement our functions nicely.
>
> Procedures return values and are invoked with CALL. Functions return
> values and are in-query callable.
>
> The fact that 'CALL' is not allowed inside a query seems to make it
> pretty darn convenient to make the additional distinction of allowing
> transactional control statements there and not in functions. You
> don't *have* to allow transactional control statements and could offer
> this feature as an essentially syntax sugar enhancement, but then run
> the risk of boxing yourself out of a useful properties of this feature
> later on because of backwards compatibility issues (in particular, the
> assumption that your are in a running transaction in the procedure
> body).
I've seen no mention of SQL/PSM. Isn't all of this covered by that?
--
Thom Brown
Twitter: @darkixion
IRC (freenode): dark_ixion
Registered Linux user: #516935
EnterpriseDB UK: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
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