Re: proposal: plpgsql - Assert statement

On Fri, Sep 5, 2014 at 2:16 AM, Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com> wrote:
> Assert is usually implemented as custom functions and used via PERFORM
> statement now
>
> -- usual current solution
> PERFORM Assert(some expression)
>
> I would to implement Assert as plpgsql internal statement due bigger
> possibilities to design syntax and internal implementation now and in
> future. More - as plpgsql statement should be compatible with any current
> code - because there should not be collision between SQL and PLpgSQL space.
> So this design doesn't break any current code.
>
> I propose following syntax with following ecosystem:
>
> ASSERT [ NOTICE, WARNING, >>EXCEPTION<< ]
> [ string expression or literal - explicit message ]
> [ USING clause - same as RAISE stmt (possible in future ) ]
> ( ROW_COUNT ( = | <> ) ( 1 | 0 ) |
> ( QUERY some query should not be empty ) |
> ( CHECK some expression should be true )
> ( IS NOT NULL expression should not be null )
>
> Every variant (ROW_COUNT, QUERY, CHECK, IS NOT NULL) has own default message

That's probably not the ugliest syntax I've *ever* seen, but it's
definitely the ugliest syntax I've seen today.

I previously proposed RAISE ASSERT ... WHERE, which seems like a nice
variant of what we've already got, but perhaps this whole discussion
merely illustrates that it's hard to get more than 1 vote for any
proposal in this area.

--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company