Re: Trigger performance

You do have to be a little careful with IN lists. Remember that a check constraint is true if it is not false - i.e. a test that evaluates to NULL has not evaluated to false and therefore is deemed to be true.

In this case you may want to include an is/is not null test on action_type, or have a NOT NULL constraint on action_type.

--

Jonathan Lewis
Yet another Oracle-related web site: http://www.jlcomp.demon.co.uk

Keith Boulton wrote in message <37eb57b1.87055981_at_news.globalnet.co.uk>...
>On Tue, 14 Sep 1999 15:29:17 GMT, Alex A. <albu_at_mailcity.com> wrote:
>
>>What is the performance impact of an insert trigger?
>>I have a table
>>ACTIONS(ACTION_TYPE, SOURCE, DESTINATION)
>>and depending on ACTION_TYPE, DESTINATION may or may not
>>be null. Is the cost of adding a trigger to enforce this
>>significant (there are only about 10 action types)? If
>>the overhead introduced by the trigger is significant,
>>I'd rather rely on the front-end checking (although this
>
>A check constraint should be faster:
>e.g. check ( ( action_type in ( 'a', 'b', 'c' ) and destination is
>not null ) or ( action_type in ( 'd', 'e', 'f') and destination is
>null )
Received on Sun Sep 19 1999 - 09:45:51 CDT