[11g] increasing efforts for select xmlserialize(content(...))) into ... from dual

Question

I wonder, that i don't get any feedback here (please see below).
Can somebody first just confirm this observation?
Oracle Database 11g Enterprise Edition Release 11.2.0.3.0 - 64bit Production
PL/SQL Release 11.2.0.3.0 - Production
"CORE 11.2.0.3.0 Production"
TNS for Linux: Version 11.2.0.3.0 - Production
NLSRTL Version 11.2.0.3.0 - Production
NLSRTL 11.2.0.3.0 Production
Oracle Database 11g Enterprise Edition 11.2.0.3.0 64bit Production
PL/SQL 11.2.0.3.0 Production
TNS for Linux: 11.2.0.3.0 Production
I recognized for my application, that there is an increasing efforts (in terms of time) for executing
(in a pl/sql package procedure invoked by a BIU trigger)
SELECT XMLSERIALIZE(CONTENT(p_xml_data)) INTO v_xml_clob FROM DUAL;
Here is a little demo sqlplus script:
create or replace package test_pkg
as
       procedure check_xml(
         p_xml_data in out nocopy xmltype);
end;
create or replace package body test_pkg
as
       procedure log(
         p_txt in varchar2)
       is
         ts     TIMESTAMP WITH TIME ZONE := systimestamp;
       begin
         dbms_output.put_line(to_char(ts, 'hhmiss.FF3') || ':' || p_txt);
       end;
       procedure check_xml(
         p_xml_data in out nocopy xmltype)
       is
         v_xml_clob CLOB;
         v_len NUMBER;
       begin
         log('check_xml(): enter');
         SELECT XMLSERIALIZE(CONTENT(p_xml_data)) INTO v_xml_clob FROM DUAL;
         log('  serialized');
         v_len := dbms_lob.getlength(v_xml_clob);
         log('check_xml(): done - length = #'  || v_len);
       exception
       when others then
           oerror_pkg.set_ora_error;
           raise;
       end;
end;
drop table test_table;
create table test_table(
       tid number(19,0),
       data xmltype
create or replace trigger BIU_TEST_TABLE
before insert or update on test_Table
for each row
declare
begin
   test_pkg.check_xml(:new.data);
end;
insert into test_table(tid, data)
select ctr_tab.ctr, '<root><node>' || ctr_tab.ctr || '</node></root>'
from (  SELECT LEVEL ctr
       FROM dual
       CONNECT BY LEVEL <= 200) ctr_tab;
The output is going like this
021543.204:check_xml(): enter
021543.204:  serialized
021543.204:check_xml(): done - length = #32
021543.206:check_xml(): enter
021543.206:  serialized
021543.206:check_xml(): done - length = #32
021543.207:check_xml(): enter
021543.208:  serialized
021543.208:check_xml(): done - length = #32
021543.209:check_xml(): enter
021543.210:  serialized
021543.210:check_xml(): done - length = #32
021543.211:check_xml(): enter
021543.212:  serialized
021543.212:check_xml(): done - length = #32
021543.214:check_xml(): enter
021543.214:  serialized
021543.214:check_xml(): done - length = #32
021549.625:check_xml(): enter
021549.664:  serialized
021549.665:check_xml(): done - length = #34
021549.708:check_xml(): enter
021549.746:  serialized
021549.747:check_xml(): done - length = #34
021549.791:check_xml(): enter
021549.829:  serialized
021549.830:check_xml(): done - length = #34
021549.874:check_xml(): enter
021549.912:  serialized
021549.913:check_xml(): done - length = #34
When i filter it with a little perl script to extract the efforts (xmlserialize / dbms_lob.getlength):
0 / 0
0 / 0
1 / 0
1 / 0
1 / 0
0 / 0
0 / 0
0 / 1
1 / 0
0 / 0
0 / 1
1 / 0
0 / 0
0 / 1
1 / 0
0 / 1
0 / 1
0 / 0
0 / 1
0 / 0
0 / 1
0 / 0
1 / 0
0 / 1
0 / 0
31 / 1
31 / 1
32 / 1
32 / 1
32 / 1
33 / 0
33 / 0
34 / 1
34 / 0
34 / 1
34 / 0
34 / 1
34 / 1
35 / 1
35 / 1
36 / 0
36 / 1
36 / 1
37 / 1
37 / 0
37 / 1
38 / 0
38 / 0
39 / 1
38 / 1
38 / 1
38 / 1
Unfortunately i can't easily change the way the insert from select is done (legacy code not under my control)
Can someone tell me, if there is a way starting with the trigger to avoid those increasing efforts?
- many thanks!
best regards,
Frank

Answer 1

[ Addendum - 24.01.2014:
  This only worked for the test/demo program. It didn't work for my application.
   For my application i really had to move the logic to the INSERT before the trigger
   - similar to the 3rd posting for my monologue(!) here.
A little step further:
I also don't have the problem if i expand the code of the PROCEDURE test_pkg.check_xml(...) directly into the trigger
- instead of invoking the PROCEDURE in the trigger:
create or replace package test_pkg
as
       procedure log(
         p_txt in varchar2);
end;
create or replace package body test_pkg
as
       procedure log(
         p_txt in varchar2)
       is
         ts     TIMESTAMP WITH TIME ZONE := systimestamp;
       begin
         dbms_output.put_line(to_char(ts, 'hhmiss.FF3') || ':' || p_txt);
       end;
end;
drop table test_table;
create table test_table( 
       tid number(19,0),
       data xmltype
create or replace trigger BIU_TEST_TABLE
before insert or update on test_Table
for each row
declare
begin 
  -- test_pkg.check_xml(:new.data);
       declare
         v_xml_clob CLOB;
         v_len NUMBER;
       begin
         test_pkg.log('check_xml(): enter');
         SELECT XMLSERIALIZE(CONTENT(:new.data)) INTO v_xml_clob FROM DUAL;
         test_pkg.log('  serialized');
         v_len := dbms_lob.getlength(v_xml_clob);
        test_pkg.log('check_xml(): done - length = #'  || v_len);
       exception
       when others then
           oerror_pkg.set_ora_error;
           raise;
       end;
   end; 
insert into test_table(tid, data)
select ctr_tab.ctr, '<root><node>' || ctr_tab.ctr || '</node></root>'
from (  SELECT LEVEL ctr
       FROM dual
       CONNECT BY LEVEL <= 200) ctr_tab;
-- rollback;
That gives some hint.
Does oracle have some problem / limit for invoking procedures (functions) from triggers?
Or only if those use certain features?
An issue about deterministic and re-entrance?
Well, that boxes me into a corner.
Because the single package procedure implements a functionality at a central place - i.e. a single central place to extend it or to fix it.
If i now have to expand its content (like a macro) into the triggers of the respective table i am in trouble.
Because those tables (and their triggers) are dynamically generated by a compiler tool of a c++ client.
This means for extension and fixes i need to change, test, deliver and deploy a list of c++ client processes :-(
Is there any way around?
How can i inform oracle that the invocation of a PL/SQL procedure is functionally identically with expanding the PL/SQL functions code into the trigger?
rgds,
Frank