Log Message:
-----------
Add a caveat pointing out that constraint exclusion doesn't work with
constraints the planner is unable to disprove, hence simple btree-compatible
conditions should be used. We've seen people try to get cute with stuff
like date_part(something) = something at least twice now. Even if we
wanted to try to teach predtest.c about the properties of date_part,
most of the useful variants aren't immutable so nothing could be proved.
Modified Files:
--------------
pgsql/doc/src/sgml:
ddl.sgml (r1.75 -> r1.76)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/ddl.sgml.diff?r1=1.75&r2=1.76)
---------------------------(end of broadcast)---------------------------
TIP 9: In versions below 8.0, the planner will ignore your desire to
choose an index scan if your joining column's datatypes do not
match
