Oracle-L: Re: Do triggers cause a context switch between SQL & PL/SQL

From: <DEEDSD_at_Nationwide.com>
Date: Tue, 01 Apr 2003 11:43:47 -0800
Message-ID: <F001.0057755D.20030401114347@fatcity.com>

I thought as much, from what I've heard and read. Does anyone know if there's a way to figure out how much overhead the switches generate? I'm guessing they would show up in trace files in the 'other CPU' category.

                                                                                                                  
                          Jared.Still_at_radisys.com                                                                 
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                          04/01/03 01:19 PM        Subject:                                          Re: Do       
                          Please respond to        triggers cause a context switch between SQL & PL/SQL           
                          ORACLE-L

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

DEEDSD_at_Nationwide.com
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04/01/2003 09:48 AM
Please respond to ORACLE-L

        To:     Multiple recipients of list ORACLE-L <ORACLE-L_at_fatcity.com>
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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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