On Tue, Sep 3, 2013 at 09:43:14PM -0400, Tom Lane wrote: > Bruce Momjian <br...@momjian.us> writes: > > This has made me adjust my goal and change it so SELECT ROW(NULL) IS > > NULL returns true, and any further nesting returns false. > > AFAICS, the only good argument for breaking backwards compatibility here > is if you can convince people that the new behavior is more conformant to > the SQL spec. Where's the chapter and verse that argues for this > interpretation?
The SQL03 standard in section 8.7, table 14, says "degree 1: null" and "degree > 1: all null". Does that mean they are considering nested rows as degree > 1, or is that the number of values in the row? A footnote says: For all R, "R IS NOT NULL" has the same result as "NOT R IS NULL" if and only if R is of degree 1. which seems to support the idea that degree is the number of values, meaning they don't discuss nesting. > And I will say once more that a patch that affects only the behavior of > eval_const_expressions can be rejected on its face. That code has to be > kept in sync with the behavior of execQual.c, not just whacked around by > itself. And then there are the NOT NULL constraint cases to worry about. I thought execQual.c was already not recursing so I didn't see a need to change that. I could not figure out how to test a NOT NULL constraint for nesting. What is driving my research here is that our current behavior is really not documentable. -- 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