Re: Assertions in PL/PgSQL

On 23 September 2013 10:10, Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com> wrote:

>
>
>
> 2013/9/22 Jaime Casanova <jaime(at)2ndquadrant(dot)com>
>
>>
>> El 21/09/2013 17:16, "Jaime Casanova" <jaime(at)2ndquadrant(dot)com> escribió:
>>
>> >
>> > On Fri, Sep 20, 2013 at 5:17 AM, Marko Tiikkaja <marko(at)joh(dot)to> wrote:
>> > > On 9/20/13 12:09 PM, Amit Khandekar wrote:
>> > >>
>> > >> On 16 September 2013 03:43, Marko Tiikkaja <marko(at)joh(dot)to> wrote:
>> > >>>
>> > >>> I think it would be extremely surprising if a command like that got
>> > >>> optimized away based on a GUC, so I don't think that would be a good
>> > >>> idea.
>> > >>
>> > >>
>> > >>
>> > >> In pl_gram.y, in the rule stmt_raise, determine that this RAISE is
>> for
>> > >> ASSERT, and then return NULL if
>> plpgsql_curr_compile->enable_assertions is
>> > >> false. Isn't this possible ?
>> > >
>> > >
>> > > Of course it's possible. But I, as a PostgreSQL user writing
>> PL/PgSQL code,
>> > > would be extremely surprised if this new cool option to RAISE didn't
>> work
>> > > for some reason. If we use ASSERT the situation is different; most
>> people
>> > > will realize it's a new command and works differently from RAISE.
>> > >
>> > >
>> >
>> > What about just adding a clause WHEN to the RAISE statement and use
>> > the level machinery (client_min_messages) to make it appear or not
>> > of course, this has the disadvantage that an EXCEPTION level will
>> > always happen... or you can make it a new loglevel that mean EXCEPTION
>> > if asserts_enabled
>> >
>>
>> meaning RAISE ASSERT of course
>>
>
> After days I am thinking so it can be a good solution
>
> syntax - enhanced current RAISE
>
> RAISE ASSERT WHEN boolean expression
>
> RAISE ASSERT 'some message' WHEN expression
>
> and we can have a GUC that controls asserts per database - possibly
> overwritten by plpgsql option - similar to current plpgsql options
>
> assert_level = [*ignore*, notice, warning, error]
>

The assert levels sound a bit like a user might be confused by these levels
being present at both places: In the RAISE syntax itself, and the assert
GUC level. But I like the syntax. How about keeping the ASSERT keyword
optional ? When we have WHEN, we anyway mean that we ware asserting that
this condition must be true. So something like this :

RAISE [ level ] 'format' [, expression [, ... ]] [ USING option =
expression [, ... ] ];
RAISE [ level ] condition_name [ USING option = expression [, ... ] ];
RAISE [ level ] SQLSTATE 'sqlstate' [ USING option = expression [, ... ] ];
RAISE [ level ] USING option = expression [, ... ];
*RAISE [ ASSERT ] WHEN bool_expression;*
RAISE ;

> comments?
>
> Regards
>
> Pavel
>
> p.s. clause WHEN can be used for other exception level - so it can be a
> interesting shortcut for other use cases.
>
> --
>> Jaime Casanova
>> 2ndQuadrant: Your PostgreSQL partner
>>
>
>