On Thu, Jul 4, 2013 at 04:29:20PM -0400, Tom Lane wrote: > Bruce Momjian <br...@momjian.us> writes: > > I developed the attached patch which properly recurses into ROW() > > records checking for NULLs; you can see it returns the right answer in > > all cases (and constant folds too): > > My recollection of the previous discussion is that we didn't have > consensus on what the "right" behavior is, so I'm not sure you can just > assert that this patch is right. In any case this is only touching the > tip of the iceberg. If we intend that rows of nulls should be null, > then we have got issues with, for example, NOT NULL column constraint > checks, which don't have any such recursion built into them. I think > the same is true for plpgsql variable NOT NULL restrictions, and there > are probably some other places.
Well we have three cases: 1 SELECT ROW(NULL) IS NULL; 2 SELECT ROW(ROW(NULL)) IS NULL; 3 SELECT ROW(ROW(ROW(NULL))) IS NULL; I think we could have them all return false, or all true, or the first one true, and the rest false. What I don't think we can justify is 1 and 2 as true, and 3 false. Can someone show how those others behave? I don't know enough to test it. > > The optimizer seems like the right place to fix this, per my patch. > > No, it isn't, or at least it's far from the only place. If we're going > to change this, we would also want to change the behavior of tests on > RECORD values, which is something that would have to happen at runtime. I checked RECORD and that behaves with recursion: SELECT RECORD(NULL) IS NULL; ?column? ---------- t SELECT RECORD(RECORD(NULL)) IS NULL; ?column? ---------- t SELECT RECORD(RECORD(RECORD(NULL))) IS NULL; ?column? ---------- t Am I missing something? -- Bruce Momjian <br...@momjian.us> http://momjian.us EnterpriseDB http://enterprisedb.com + It's impossible for everything to be true. + -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers