---------- Forwarded message ---------- From: Oleg Serov <[EMAIL PROTECTED]> Date: 2008/9/27 Subject: Re: Null row vs. row of nulls in plpgsql To: Tom Lane <[EMAIL PROTECTED]>
I'm newbie, but i think that adding bool flag to PLpgSQL_row isnull will handle the problem(like in PLpgSQL_var); 2008/9/27 Tom Lane <[EMAIL PROTECTED]> I looked a bit at the bug report here: > http://archives.postgresql.org/pgsql-bugs/2008-09/msg00164.php > > ISTM that the fundamental problem is that plpgsql doesn't distinguish > properly between a null row value (eg, "null::somerowtype") and a > row of null values (eg, "row(null,null,...)::somerowtype"). When that > code was designed, our main SQL engine was pretty fuzzy about the > difference too, but now there is a clear semantic distinction. > > For plpgsql's RECORD variables this doesn't seem hard to fix: just > take out the code in exec_move_row() that manufactures a row of nulls > when the input is null, and maybe make a few small adjustments > elsewhere. For ROW variables there's a bigger problem, because those > are represented by a list of per-field variables, which doesn't > immediately offer any way to represent overall nullness. I think it > could be dealt with by adding an explicit "the row as a whole is null" > flag to struct PLpgSQL_row. I haven't tried to code it though, so I'm > not sure if there are gotchas or unreasonably large code changes needed > to make it happen. > > I thought for a little bit about whether we couldn't get rid of ROW > variables entirely, or at least make them work more like RECORD variables > by storing a HeapTuple instead of a list of per-field variables. But > I soon found out that the reason to have them is to be able to describe > the assignment target of SQL statements that assign to multiple scalar > variables, eg "SELECT ... INTO x,y,z". > > Comments? > > regards, tom lane >
