Re: DELETE FROM t WHERE EXISTS

"Dan Langille" <dan@langille.org> writes:
> So I tried this:

> DELETE FROM clp 
> WHERE NOT EXISTS (
> SELECT * 
> FROM clp 
> ORDER BY commit_date 
> LIMIT 100);

> Uhh uhh, nothing deleted.  I don't understand why.

Because the inner SELECT is a constant: you forgot to make it depend on
the current outer row.  So EXISTS succeeds at every row, unless clp is
already empty.
        regards, tom lane