Re: proposal: plpgsql - Assert statement

On 09/17/2014 03:36 PM, Peter Eisentraut wrote:
> On 9/17/14 3:04 PM, Pavel Stehule wrote:
>> What is difference between content of variable or content of database?
>> You can test any prerequisite, but when this prerequisite is not solved,
>> than exception is very very hard without possible handling.
>
> If the assertion tests arbitrary Boolean expressions, then we can't stop
> the user from abusing them.

Exactly. Doing something like
    ASSERT (select count(*) from foo        where fk not in (select pk from bar)) = 0;

is a perfectly fine, arbitrary boolean expression. It will probably work 
well in a development environment too. And I am very sure that it will 
not scale well once that code gets deployed. And I know how DBAs react 
to the guaranteed following performance problem. They will disable ALL 
assert ... or was there some sort of assert class system proposed that I 
missed?

>
> But it's another thing if we design specific syntax that encourages such
> abuse, as proposed earlier.

The design should explicitly discourage that sort of nonsense.


Jan


-- 
Jan Wieck
Senior Software Engineer
http://slony.info