Обсуждение: not logging caught exceptions

Is it at all reasonable to try to create some mechanism so that
exceptions (elog) that are caught and not rethrown do not end up in the
log?  For example, when you write code that does something like

try   insert
catch unique_constraint_violation   update
end try

this will end up cluttering the logs with all the constraint violation
messages.

Now, we probably don't want to just suppress all logging in a TRY block
until the END_TRY.  So maybe this could be an argument to TRY or a
separate statement that would typically be run right after TRY that
names exception types to handle specially.  Higher level languages such
as PL/pgSQL could then peek ahead to the catch block to set this up.

Comments?

Peter Eisentraut <peter_e@gmx.net> writes:
> Is it at all reasonable to try to create some mechanism so that
> exceptions (elog) that are caught and not rethrown do not end up in the
> log?  For example, when you write code that does something like

> try
>     insert
> catch unique_constraint_violation
>     update
> end try

> this will end up cluttering the logs with all the constraint violation
> messages.

Really?  It's not supposed to.
        regards, tom lane

On ons, 2009-11-11 at 19:45 -0500, Tom Lane wrote:
> > try
> >     insert
> > catch unique_constraint_violation
> >     update
> > end try
> 
> > this will end up cluttering the logs with all the constraint violation
> > messages.
> 
> Really?  It's not supposed to.

There might be a different bug here.  This doesn't look right:

CREATE LANGUAGE plpgsql;

CREATE TABLE keytest (a int PRIMARY KEY, b text);

CREATE OR REPLACE FUNCTION insert_or_update(new_a int, new_b text)
RETURNS text
LANGUAGE plpgsql
AS $$
BEGIN   INSERT INTO keytest VALUES (new_a, new_b);   RETURN 'inserted';
EXCEPTION WHEN integrity_constraint_violation THEN   UPDATE keytest SET a = new_a, b = new_b;   RETURN 'updated';
END;
$$;

SELECT insert_or_update(1, 'one');
SELECT insert_or_update(1, 'one');
SELECT insert_or_update(2, 'two');
SELECT insert_or_update(2, 'two');

Results in:
insert_or_update
------------------inserted
(1 row)
insert_or_update
------------------updated
(1 row)
insert_or_update
------------------inserted
(1 row)

ERROR:  duplicate key value violates unique constraint "keytest_pkey"
CONTEXT:  SQL statement "UPDATE keytest SET a =  $1 , b =  $2 "
PL/pgSQL function "insert_or_update" line 6 at SQL statement

Peter Eisentraut <peter_e@gmx.net> writes:
> There might be a different bug here.  This doesn't look right:

The UPDATE lacks a WHERE clause :-(
        regards, tom lane