Re: plpgsql - additional extra checks

2017-01-13 2:46 GMT+01:00 Jim Nasby <Jim(dot)Nasby(at)bluetreble(dot)com>:

> On 1/11/17 5:54 AM, Pavel Stehule wrote:
>
>> + <term><varname>too_many_rows</varname></term>
>> + <listitem>
>> + <para>
>> + When result is assigned to a variable by <literal>INTO</literal>
>> clause,
>> + checks if query returns more than one row. In this case the
>> assignment
>> + is not deterministic usually - and it can be signal some issues in
>> design.
>>
>
> Shouldn't this also apply to
>
> var := blah FROM some_table WHERE ...;
>

yes, it is possible.

I am not sure - how to document it. This pattern is undocumented and it is
side effect of our parser.

If somebody use var := (SELECT xxx FROM ..)

what is correct syntax, then exactly only one row is required.

But the extra check is ok, if we technically allows this syntax.

Regards

Pavel

> ?
>
> AIUI that's one of the beefs the plpgsql2 project has.
>
> FWIW, I'd also be in favor of a NOMULTI option to INTO, but I don't see
> any way to do something like that with var := blah FROM.
> --
> Jim Nasby, Data Architect, Blue Treble Consulting, Austin TX
> Experts in Analytics, Data Architecture and PostgreSQL
> Data in Trouble? Get it in Treble! http://BlueTreble.com
> 855-TREBLE2 (855-873-2532)
>