| From: | "David E(dot) Wheeler" <david(at)kineticode(dot)com> |
|---|---|
| To: | Jeff Davis <pgsql(at)j-davis(dot)com> |
| Cc: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Brendan Jurd <direvus(at)gmail(dot)com>, PostgreSQL-development Hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: When is a record NULL? |
| Date: | 2009-07-25 23:20:17 |
| Message-ID: | 45BA8563-CF9A-40ED-80D5-31A9BB7FBA84@kineticode.com |
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| Lists: | pgsql-hackers |
On Jul 25, 2009, at 9:24 AM, Jeff Davis wrote:
> I don't think you want the "NOT x IS NULL" part at all -- that will
> evaluate to false when x = rec(NULL,NULL). I think you just want the
> "x
> IS DISTINCT FROM NULL" part, right? Will that work?
Nope, infinite loop when because `ROW(null, null)` and `ROW()` are
both distinct from null:
try=# select row(null, null) is distinct from null, row() is distinct
from null;
?column? | ?column?
----------+----------
t | t
(1 row)
So I still can't tell when I've exhausted a cursor.
Best,
David
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