On 6/14/2011 8:08 PM, David Johnston wrote:
alter table tblissue add constraint
"tblissue_parentissueid_fkey_casc_del" FOREIGN KEY (parentissueid)
REFERENCES tblissue(issueid) ON DELETE CASCADE;
=============================================
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.
You only explicitly deleted a single row; all the rest were done via the
CASCADE and thus are not counted in the delete count.
Make sense; If I delete a record and see "DELETE 1000" because 999 FK
records were deleted I would have no way of know if I foo-barred the DELETE
query itself and actually killed 1000 records using the DELETE itself or got
it right and hit the 1 intended record and simply got 999 more deletions
indirectly.
I can see where a more helpful response would be: "DELETE 1 \n NOTICE: 999
FK references were deleted due to Cascade" but the "DELETE 1" MUST show me
explicitly how many records were deleted solely due to my DELETE statement's
FROM and WHERE clauses.
Agree 100%.
I am not a big fan of CASCADING effects (I rather do it 'by hand'), but
in this case it was a really easy solution.
Thanks you for your response.
Regards,
Erwin Moller
David J.
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