Re: Assertions in PL/PgSQL

2013/9/15 Marko Tiikkaja <marko(at)joh(dot)to>

> On 2013-09-15 00:09, Pavel Stehule wrote:
>
>> this is a possibility for introduction a new hook and possibility
>> implement
>> asserions and similar task in generic form (as extension). it can be
>> assertions, tracing, profiling.
>>
>
> You can already do tracing and profiling in an extension. I don't see
> what you would put inside the function body for these two, either.
>

you cannot mark a tracing points explicitly in current (unsupported now)
extensions.

These functions share same pattern:

CREATE OR REPLACE FUNCTION assert(boolean)
RETURNS void AS $$
IF current_setting('plpgsq.assertions') = 'on' THEN
IF $1 THEN
RAISE EXCEPTION 'Assert fails';
END IF;
END IF;
END;
$$ LANGUAGE plpgsql;

CREATE OR REPLACE FUNCTION trace(text)
RETURNS void AS $$
IF current_setting('plpgsq.trace') = 'on' THEN
RAISE WARNING 'trace: %', $1; END IF;
END;
$$ LANGUAGE plpgsql;

Depends on usage, these functions will not be extremely slow against to
builtin solution - can be faster, if we implement it in C, and little bit
faster if we implement it as internal PLpgSQL statement. But if you use a
one not simple queries, then overhead is not significant (probably).

You have to watch some global state variable and then execute (or not) some
functionality.

Regards

Pavel

>
>
> Regards,
> Marko Tiikkaja
>