|This patch fixes a backend crash that happens sometimes when you try to

|This patch fixes a backend crash that happens sometimes when you try to
|join on a field that contains NULL in some rows.  Postgres tries to
|compute a hash value of the field you're joining on, but when the field
|is NULL, the pointer it thinks is pointing to the data is really just
|pointing to random memory.  This forces the hash value of NULL to be 0.
|
|It seems that nothing matches NULL on joins, even other NULL's (with or
|without this patch).  Is that what's supposed to happen?
|

Submitted by: Dan McGuirk <mcguirk@indirect.com>