I found the row handling for "IS [NOT] NULL" confusing for row-valued
expressions, so I added the attached documentation sentence.
--
Bruce Momjian <bruce@momjian.us> http://momjian.us
EnterpriseDB http://enterprisedb.com
+ If your life is a hard drive, Christ can be your backup. +
Index: doc/src/sgml/func.sgml
===================================================================
RCS file: /cvsroot/pgsql/doc/src/sgml/func.sgml,v
retrieving revision 1.427
diff -c -c -r1.427 func.sgml
*** doc/src/sgml/func.sgml 4 Apr 2008 18:45:36 -0000 1.427
--- doc/src/sgml/func.sgml 7 Apr 2008 00:46:46 -0000
***************
*** 344,350 ****
<literal>IS NULL</> is true when the row expression itself is null
or when all the row's fields are null, while
<literal>IS NOT NULL</> is true when the row expression itself is non-null
! and all the row's fields are non-null.
This definition conforms to the SQL standard, and is a change from the
inconsistent behavior exhibited by <productname>PostgreSQL</productname>
versions prior to 8.2.
--- 344,354 ----
<literal>IS NULL</> is true when the row expression itself is null
or when all the row's fields are null, while
<literal>IS NOT NULL</> is true when the row expression itself is non-null
! and all the row's fields are non-null. Because of this behavior,
! <literal>IS NULL</> and <literal>IS NOT NULL</> do not always return
! inverse results for row-valued expressions, i.e. a row-valued
! expression that contains both NULL and non-null values will return false
! for both tests.
This definition conforms to the SQL standard, and is a change from the
inconsistent behavior exhibited by <productname>PostgreSQL</productname>
versions prior to 8.2.
