Re: PL/pgSQL 2

On 09/02/2014 07:12 PM, Joel Jacobson wrote:
> On Tue, Sep 2, 2014 at 6:03 PM, Heikki Linnakangas
> <hlinnakangas@vmware.com> wrote:
>> 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.
>
> So instead of one line of code, I would need to write two lines of
> code at almost *all* places where a currently have an UPDATE. :-(

Right. Doesn't really seem that bad, to be honest. You can put it on the 
same line if you wish.

> I think the problem with my perspective is my ambitions. I use
> PL/pgSQL not as a secondary language, but it's my primary language for
> developing applications.

Sure, a lot of people do that.

> For me, updating a row, is like setting a variable in a normal language.
> No normal language would require two rows to set a variable.
> It would be like having to do:
>     my $var = 10;
>     die unless $var == 10;
> in Perl to set a variable.

I don't think most applications are like that. See Kevin's comments 
about doing things in a set-oriented way instead of row-by-row. I know 
I've changed several procedures from the row-oriented style, looping 
over rows with a FOR loop, updating each one individually, to 
set-oriented style with a single UPDATE for a bunch of rows. It makes 
for more concise code, and performs better. I'm sure there are 
counter-examples, and I've also written many UPDATE statements that are 
expected to update exactly one row, but I find an ASSERT would be 
adequate for that.

- Heikki