Re: PL/pgSQL 2

On 09/02/2014 06:44 PM, Joel Jacobson wrote:
> On Tue, Sep 2, 2014 at 5:08 PM, Kevin Grittner <kgrittn@ymail.com> wrote:
>> Marko Tiikkaja <marko@joh.to> wrote:
>>> No, but your code can have a bug.
>>
>> So the main use case is to allow buggy functions which are deployed
>> to production without adequate testing to be detected?  Bugs like
>> not getting the primary key column(s) right?  I think it would be
>> great to have some way to generate an error if a given statement
>> doesn't affect exactly one row, but the above is a pretty weak
>> argument for making it a default behavior.
>
> Instead of writing unit tests for such trivial things as updating one row
> and testing if it got updated, it's better to make such unit tests
> asserts instead,
> which is exactly what we achieve if we provide a syntax to throw an error if
> not exactly 1 row was affected.

Marko posted a patch to add assertions to PL/pgSQL last year, see 
http://www.postgresql.org/message-id/5234AF3F.4000409@joh.to. It was a 
long thread, but in the end I think everyone was more or less OK with 
the syntax "ASSERT <condition>;". I also think that syntax is fine, and 
it would be a nice feature, assuming we can avoid reserving the ASSERT 
keyword.

I think that would actually be a good way to enforce the rule that an 
UPDATE only updates a single row. Just put a "ASSERT ROW_COUNT=1;" after 
the update.

- Heikki