psql reports back wrong number of affected rows.

Hi,

I was surprised by the following behavior of Postgres (8.1).
Consider the following table and constraint:

=============================================
CREATE TABLE tblissue(
  issueid SERIAL PRIMARY KEY,
  title TEXT,
  comment TEXT,
  createtimestamp TIMESTAMP DEFAULT (current_timestamp),
  parentissueid INTEGER,
  caseclosed CHAR(1)
);

alter table tblissue add constraint
"tblissue_parentissueid_fkey_casc_del" FOREIGN KEY (parentissueid)
REFERENCES tblissue(issueid) ON DELETE CASCADE;
=============================================

So the parentissueid references the same table's PK, but can NULL too.
All fine so far.

Next I insert a few rows that use not null values for parentissueid, so
the foreign key constraint is in effect.
Suppose I created a few rows that have 1 as value for parentissueid.

Then:
delete from tblissue where issueid=1;
DELETE 1

Postgresql now deletes all rows that had a 1 for parentissueid. (5 in my
testcase).
That was correct, and as I intended, but why does Postgres answer
"DELETE 1" instead of DELETE 6?

Can somebody explain that to me please?
Thanks for your time.

Regards,
Erwin Moller

PS: I found a few possible relevant postings. One of them (by Tom Lane)
pointed to here:
http://www.postgresql.org/docs/8.0/static/rules-status.html
but I am still unsure if it is relevant.