Re: enhance SPI to support EXECUTE commands

čt 5. 9. 2019 v 10:57 odesílatel Quan Zongliang <
zongliang(dot)quan(at)postgresdata(dot)com> napsal:

> On 2019/9/5 16:31, Pavel Stehule wrote:
> >
> >
> > čt 5. 9. 2019 v 10:25 odesílatel Quan Zongliang
> > <zongliang(dot)quan(at)postgresdata(dot)com
> > <mailto:zongliang(dot)quan(at)postgresdata(dot)com>> napsal:
> >
> > On 2019/9/5 15:09, Pavel Stehule wrote:
> > >
> > >
> > > čt 5. 9. 2019 v 8:39 odesílatel Quan Zongliang
> > > <zongliang(dot)quan(at)postgresdata(dot)com
> > <mailto:zongliang(dot)quan(at)postgresdata(dot)com>
> > > <mailto:zongliang(dot)quan(at)postgresdata(dot)com
> > <mailto:zongliang(dot)quan(at)postgresdata(dot)com>>> napsal:
> > >
> > > Dear hackers,
> > >
> > > I found that such a statement would get 0 in PL/pgSQL.
> > >
> > > PREPARE smt_del(int) AS DELETE FROM t1;
> > > EXECUTE 'EXECUTE smt_del(100)';
> > > GET DIAGNOSTICS j = ROW_COUNT;
> > >
> > > In fact, this is a problem with SPI, it does not support
> > getting result
> > > of the EXECUTE command. I made a little enhancement. Support
> > for the
> > > number of rows processed when executing INSERT/UPDATE/DELETE
> > statements
> > > dynamically.
> > >
> > >
> > > Is there some use case for support this feature?
> > >
> > A user deletes the data in PL/pgSQL using the above method, hoping
> > to do
> > more processing according to the number of rows affected, and found
> > that
> > each time will get 0.
> >
> > Sample code:
> > PREPARE smt_del(int) AS DELETE FROM t1 WHERE c=$1;
> > EXECUTE 'EXECUTE smt_del(100)';
> > GET DIAGNOSTICS j = ROW_COUNT;
> >
> >
> > This has not sense in plpgsql. Why you use PREPARE statement explicitly?
> >
> Yes, I told him to do it in other ways, and the problem has been solved.
>
> Under psql, we can get this result
>
> flying=# EXECUTE smt_del(100);
> DELETE 1
>
> So I think this may be the negligence of SPI, it should be better to
> deal with it.
>

Personally, I would not to support features that allows bad code.

Pavel

>
> >
> > IF j=1 THEN
> > do something
> > ELSIF j=0 THEN
> > do something
> >
> > Here j is always equal to 0.
> >
> >
> >
> > Regards
> >
> > > Regards
> > >
> > > Pavel
> > >
> > >
> > > Regards,
> > > Quan Zongliang
> > >
> >
>
>