Since you the action switches from SQL to PL/SQL to enforce the trigger,
it sounds like a context switch to me.
FYI: This can be improved somewhat by adding "and rownum < 2 " into the
WHERE clauses of these. There will be noticable improvement when there
are many child rows.
Jared
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04/01/2003 09:48 AM
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Subject: Do triggers cause a context switch between SQL & PL/SQL
Question:
If some idiot decides to circumvent Oracle's referential integrity and
re-implement it by using triggers (insert, update, delete) that checks the
foreign (parent/child) key fields in other tables like this,
declare numrows INTEGER;
begin
-- ApplicationForm is used if the state and other criteria match that
in
-- ApplicationFormCriteria ON PARENT DELETE RESTRICT
select count(*) into numrows
from ApplicationFormCriteria
where
ApplicationFormCriteria.applicationFormId =
:old.applicationFormId;
if (numrows > 0)
then
raise_application_error(
-20343,
'Database Integrity Violation - Cannot DELETE row in Table
''ApplicationForm'' because referencing row exists in table
''ApplicationFormCriteria'' for Primary Key (applicationFormId)=' ||
:old.applicationFormId
);
end if;
end;
would it cause context switching between the SQL & PL/SQL engines?
Yes, some genius did this in one of our databases. Two hundred
third/fourth normal form tables enforced by 800 triggers... I have him
registered to be stoned in public.
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