On 02/09/14 18:20, Joel Jacobson wrote:
On Tue, Sep 2, 2014 at 6:09 PM, Kevin Grittner <kgri...@ymail.com> wrote:
Joel Jacobson <j...@trustly.com> wrote:
Sorry for being unclear, I didn't mean to suggest the main concern is
updating *all* rows.
The main concern is when you have a rather complex UPDATE WHERE clause,
aiming to update exactly one row. Some of the expressions might be
assertions, to just double-verify the values and to make it stand-out
you are checking those expressions.
These are two different problems which probably need two different
solutions. Making the default behavior of a set-based command that
it throw an error if the resulting set is not exactly one row
doesn't seem like the right solution to either one of them.
I see your point.
Basically, we have two types of applications where PL/pgSQL is commonly used.
a) OLTP applications where you typically operate on one row for each
UPDATE command.
b) Data warehouseing applications where you process multiple rows in
each UPDATE command.
Both have different desired default behaviours of the different
set-based commands used in PL/pgSQL.
I think both are important enough to motivate a nice syntax for both use-cases.
If we cannot change the default behaviour of UPDATE, then I vote for
the eariler proposed STRICT UPDATE syntax.
I see both use cases, but I think the SQL default are set
operations. For this particular point, if there would be just a syntax
change rather than a new language, in the line of the "ONE ROW UPDATE"
syntax, I'd say "UNIQUE UPDATE". This {ONE ROW, UNIQUE} syntax may also
enforce having a WHERE clause. I find both better than the STRICT, which
is not doing what -you may think- it does.
Regards,
Álvaro
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