Abstract: Oracle released a feature in 10g Release 2 they thought worthy of facilitating in previous versions via patch sets - so I thought it was worthy enough for a closer look. Conditional compilation isn't a foreign concept in the programming world, and for the developer aficionado it's a wonderful paradigm to explore. Conditional compilation was designed with the main intention of being able to create database version specific code. With the recent advent of 11g, developers can actually start adding 11g features to their 10g code today! However it provides the savvy PL/SQL developer to enhance their code in more ways than just gearing up for the next release… Dust of your software engineering hats and discover how to utilise conditional compilation to explore concepts such as latent self tracing code; latent assertions; and enhanced prototyping for your unit tests. This seminar will illustrate several examples of conditional compilation that will open your mind; ultimately benefit your users; and can be implemented as far back as 9.2!

1. SAGE Computing Services
Customised Oracle Training Workshops and Consulting
Creative Conditional Compilation
… and “raising the bar” with yourPL/SQL
Sco tt We sle y
Systems Consultant

3. The example everybody’s seen…
FUNCTION qty_booked(p_resource IN VARCHAR2
,p_date IN DATE)
RETURN NUMBER
$IF dbms_db_version.ver_le_10 $THEN
$ELSE RESULT_CACHE $END
IS
li_total PLS_INTEGER := 0;
BEGIN
SELECT SUM(b.qty)
INTO li_total
FROM bookings b, events e
WHERE p_date BETWEEN e.start_date AND e.end_date
AND b.resource = p_resource;
RETURN li_total
END qty_booked;

4. The example everybody’s seen…
FUNCTION qty_booked(p_resource IN VARCHAR2FUNCTION qty_booked(p_resource IN VARCHAR2
,p_date IN DATE),p_date IN DATE)
RETURN NUMBERRETURN NUMBER
$IF dbms_db_version.ver_le_10 $THEN
$ELSE RESULT_CACHE $END
ISIS
li_total PLS_INTEGER := 0;li_total PLS_INTEGER := 0;
BEGINBEGIN
SELECT SUM(b.qty)SELECT SUM(b.qty)
INTO li_totalINTO li_total
FROM bookings b, events eFROM bookings b, events e
WHERE p_date BETWEEN e.start_date AND e.end_dateWHERE p_date BETWEEN e.start_date AND e.end_date
AND b.resource = p_resource;AND b.resource = p_resource;
RETURN li_totalRETURN li_total
END qty_booked;END qty_booked;

5. • PL/SQL User’s Guide & Reference
10g Release 2
– Fundamentals of the PL/SQL Language
• Conditional Compilation

6. Availability
• 11g
• 10g Release 2
– Enabled out of the box
• 10.1.0.4 – Once patched, enabled by default
– Disable using “_parameter”
• 9.2.0.6 – Once patched, disabled by default
– Enable using “_parameter”

7. Catch 22
INDICES OF

8. Catch 22
Conditional
Compilation
Patch
INDICES OF

9. Facilitates removal of unnecessary code at compile time
Performance
Readability
Accuracy Testing
It's cool!

10. Selection Directives
$IF boolean_static_expression $THEN text
[ $ELSIF boolean_static_expression $THEN text ]
[ $ELSE text ]
$END
Inquiry Directives
DBMS_OUTPUT.PUT_LINE($$PLSQL_LINE);
ALTER SESSION SET PLSQL_CCFLAGS='max_sentence:100';
IF sentence > $$max_sentence THEN
Error Directives
$IF $$PLSQL_OPTIMIZE_LEVEL != 2
$THEN
$ERROR 'intensive_program must be compiled with
maximum optimisation'
$END
$END
Semantics

11. First demo
cc1a
cc1b
cc1c
cc1d

12. Inquiry Directives

13. << anon >>
BEGIN
DBMS_OUTPUT.PUT_LINE('Unit:'||$$PLSQL_UNIT);
DBMS_OUTPUT.PUT_LINE('Line:'||$$PLSQL_LINE);
END anon;
/
Unit:
Line:4

14. > CREATE OR REPLACE PROCEDURE sw_test IS
BEGIN
DBMS_OUTPUT.PUT_LINE('Unit:'||$$PLSQL_UNIT);
DBMS_OUTPUT.PUT_LINE('Line:'||$$PLSQL_LINE);
END sw_test;
/
Procedure created.
> exec sw_test
Unit:SW_TEST
Line:4

15. ALTER SESSION SET PLSQL_CCFLAGS = 'max_sentence:100';
Session altered.

16. > BEGIN
IF p_sentence > $$max_sentence THEN
DBMS_OUTPUT.PUT_LINE('Parole Available');
ELSE
DBMS_OUTPUT.PUT_LINE('Life');
END IF;
END;
/
Life

17. ALTER SYSTEM SET PLSQL_CCFLAGS =
'VARCHAR2_SIZE:100, DEF_APP_ERR:-20001';
DECLARE
lc_variable_chr VARCHAR2($$VARCHAR2_SIZE);
e_def_app_err EXCEPTION;
PRAGMA EXCEPTION_INIT (e_def_app_err, $$DEF_APP_ERR);
BEGIN
--> rest of your code
END anon;
/

18. Reuse Settings

19. ALTER SESSION SET PLSQL_CCFLAGS = 'MY_PI:314';
CREATE OR REPLACE PROCEDURE universe_alpha IS
BEGIN
DBMS_OUTPUT.PUT_LINE('Alpha pi = '||$$my_pi/100);
END;
CREATE OR REPLACE PROCEDURE universe_gamma IS
BEGIN
DBMS_OUTPUT.PUT_LINE('Gamma pi = '||$$my_pi/100);
END;
CREATE OR REPLACE PROCEDURE universe_oz IS
BEGIN
DBMS_OUTPUT.PUT_LINE('Oz pi = '||$$my_pi/100);
END;ALTER PROCEDURE universe_alpha COMPILE
PLSQL_CCFLAGS = 'MY_PI:289'
REUSE SETTINGS; ALTER PROCEDURE universe_gamma COMPILE
PLSQL_CCFLAGS = 'MY_PI:423'
REUSE SETTINGS;
> BEGIN
universe_alpha;
universe_gamma;
universe_oz;
END;
/
Alpha pi = 2.89
Gamma pi = 4.23
Oz pi = 3.14

20. Some actual examples?

21. Using new version code today
$IF dbms_db_version.ver_le_10 $THEN
-- version 10 and earlier code
$ELSIF dbms_db_version.ver_le_11 $THEN
-- version 11 code
$ELSE
-- version 12 and later code
$END

22. 10.1 vs 10.2 dbms_output

23. CREATE OR REPLACE PROCEDURE sw_debug (p_text IN
VARCHAR2) IS
$IF $$sw_debug_on $THEN
l_text VARCHAR2(32767);
$END
BEGIN
$IF $$sw_debug_on $THEN
-- Let’s provide debugging info
$IF dbms_db_version.ver_le_10_1 $THEN
-- We have to truncate for <= 10.1
l_text := SUBSTR(p_text, 1 ,200);
$ELSE
l_text := p_text;
$END
DBMS_OUTPUT.PUT_LINE(p_text);
$ELSE
-- No debugging
NULL;
$END
END sw_debug;

24. CREATE OR REPLACE PROCEDURE sw_debug (p_text INCREATE OR REPLACE PROCEDURE sw_debug (p_text IN
VARCHAR2) ISVARCHAR2) IS
$IF $$sw_debug_on $THEN
l_text VARCHAR2(32767);
$END
BEGINBEGIN
$IF $$sw_debug_on $THEN
-- Let’s provide debugging info
$IF dbms_db_version.ver_le_10_1 $THEN
-- We have to truncate for <= 10.1
l_text := SUBSTR(p_text, 1 ,200);
$ELSE
l_text := p_text;
$END
DBMS_OUTPUT.PUT_LINE(p_text);
$ELSE$ELSE
-- No debugging-- No debugging
NULL;NULL;
$END$END
END sw_debug;END sw_debug;

25. CREATE OR REPLACE PROCEDURE sw_debug (p_text INCREATE OR REPLACE PROCEDURE sw_debug (p_text IN
VARCHAR2) ISVARCHAR2) IS
$IF $$sw_debug_on $THEN$IF $$sw_debug_on $THEN
l_text VARCHAR2(32767);l_text VARCHAR2(32767);
$END$END
BEGINBEGIN
$IF $$sw_debug_on $THEN$IF $$sw_debug_on $THEN
-- Let’s provide debugging info-- Let’s provide debugging info
$IF dbms_db_version.ver_le_10_1 $THEN
-- We have to truncate for <= 10.1
l_text := SUBSTR(p_text, 1 ,255);
$ELSE$ELSE
l_text := p_text;l_text := p_text;
$END$END
DBMS_OUTPUT.PUT_LINE(p_text);DBMS_OUTPUT.PUT_LINE(p_text);
$ELSE$ELSE
-- No debugging-- No debugging
NULL;NULL;
$END$END
END sw_debug;END sw_debug;

26. 10g vs 11g result_cache
FUNCTION quantity_ordered
(p_item_id IN items.item_id%TYPE)
RETURN NUMBER
$IF dbms_version.ver_le_10 $THEN
-- nothing
$ELSE
RESULT_CACHE
$END
IS
BEGIN
...

27. 9i vs 10g Bulk Insert

28. CREATE OR REPLACE PACKAGE BODY sw_bulk_insert IS
PROCEDURE sw_insert (sw_tab IN t_sw_tab) IS
BEGIN
$IF dbms_db_version.ver_le_9 $THEN
DECLARE
l_dense t_sw_tab;
ln_index PLS_INTEGER := sw_tab.FIRST;
BEGIN
<< dense_loop >>
WHILE (l_index IS NOT NULL) LOOP
l_dense(l_dense.COUNT + 1) := sw_tab(l_index);
l_index := sw_tab.NEXT(l_index);
END LOOP dense_loop;
FORALL i IN 1..l_dense.COUNT
INSERT INTO sw_table VALUES l_dense(i);
END;
$ELSE
FORALL i IN INDICES OF sw_tab
INSERT INTO sw_table
VALUES sw_tab(i);
$END
END sw_insert;
END sw_bulk_insert;

29. CREATE OR REPLACE PACKAGE BODY sw_bulk_insert IS
PROCEDURE sw_insert (sw_tab IN t_sw_tab) IS
BEGIN
$IF dbms_db_version.ver_le_9 $THEN
DECLARE
l_dense t_sw_tab;
ln_index PLS_INTEGER := sw_tab.FIRST;
BEGIN
<< dense_loop >>
WHILE (l_index IS NOT NULL) LOOP
l_dense(l_dense.COUNT + 1) := sw_tab(l_index);
l_index := sw_tab.NEXT(l_index);
END LOOP dense_loop;
FORALL i IN 1..l_dense.COUNT
INSERT INTO sw_table VALUES l_dense(i);
END;
$ELSE$ELSE
FORALL i IN INDICES OF sw_tabFORALL i IN INDICES OF sw_tab
INSERT INTO sw_tableINSERT INTO sw_table
VALUES sw_tab(i);VALUES sw_tab(i);
$END$END
END sw_insert;
END sw_bulk_insert;

30. CREATE OR REPLACE PACKAGE BODY sw_bulk_insert IS
PROCEDURE sw_insert (sw_tab IN t_sw_tab) IS
BEGIN
$IF dbms_db_version.ver_le_9 $THEN$IF dbms_db_version.ver_le_9 $THEN
DECLAREDECLARE
l_dense t_sw_tab;l_dense t_sw_tab;
ln_index PLS_INTEGER := sw_tab.FIRST;ln_index PLS_INTEGER := sw_tab.FIRST;
BEGINBEGIN
<< dense_loop >><< dense_loop >>
WHILE (l_index IS NOT NULL) LOOPWHILE (l_index IS NOT NULL) LOOP
l_dense(l_dense.COUNT + 1) := sw_tab(l_index);l_dense(l_dense.COUNT + 1) := sw_tab(l_index);
l_index := sw_tab.NEXT(l_index);l_index := sw_tab.NEXT(l_index);
END LOOP dense_loop;END LOOP dense_loop;
FORALL i IN 1..l_dense.COUNTFORALL i IN 1..l_dense.COUNT
INSERT INTO sw_table VALUES l_dense(i);INSERT INTO sw_table VALUES l_dense(i);
END;END;
$ELSE
FORALL i IN INDICES OF sw_tab
INSERT INTO sw_table
VALUES sw_tab(i);
$END
END sw_insert;
END sw_bulk_insert;

31. Paradigm Examples

32. Latent debugging code

33. CREATE OR REPLACE PACKAGE pkg_debug IS
debug_flag CONSTANT BOOLEAN := FALSE;
END pkg_debug;
/
CREATE OR REPLACE PROCEDURE sw_proc IS
BEGIN
$IF pkg_debug.debug_flag $THEN
dbms_output.put_line ('Debug=T');
$ELSE
dbms_output.put_line ('Debug=F');
$END
END sw_proc;
/

34. Assertions

35. “Assertions should be used to document
logically impossible situations —
Development tool
Testing Aid
In-line Documentation
if the ‘impossible’ occurs,
then something fundamental is clearly wrong.
This is distinct from error handling.”
Run-time Cost

36. Latent Assertions

37. “The removal of assertions from production code is
almost always done automatically.
It usually is done via conditional compilation.”

38. $IF $$asserting
OR CC_assertion.asserting
$THEN
IF p_param != c_pi*r*r THEN
raise_application_error(..
END IF;
$END
-- individual program unit
-- entire application

39. Testing subprograms only in package body

40. CREATE PACKAGE universe IS
PROCEDURE create_sun;
PROCEDURE create_planets;
-- CC test procedure
PROCEDURE test_orbit;
END universe;
CREATE PACKAGE BODY universe IS
-- Private
PROCEDURE orbit IS .. END;
-- Public
PROCEDURE create_sun IS .. END;
PROCEDURE create_planets IS .. END;
-- Testers
PROCEDURE test_orbit IS
BEGIN
$IF $$testing $THEN
orbit;
$ELSE
RAISE program_error;
$END
END test_orbit;
END universe;

41. CREATE PACKAGE universe IS
PROCEDURE create_sun;
PROCEDURE create_planets;
-- CC test sequence
PROCEDURE test_run;
END universe;
CREATE PACKAGE BODY universe IS
-- Private
PROCEDURE orbit IS .. END;
-- Public
PROCEDURE create_sun IS .. END;
PROCEDURE create_planets IS .. END;
-- Test sequence
PROCEDURE test_run IS
BEGIN
$IF $$testing $THEN
create_sun;
create_planets;
orbit;
$ELSE
RAISE program_error;
$END
END test_run;
END universe;

42. Mock objects

43. FUNCTION get_emp(p_emp_id IN emp.emp_id%TYPE)
RETURN t_emp IS
l_emp t_emp;
BEGIN
$IF $$mock_emp $THEN
l_emp.emp_name := 'Scott';
..
RETURN l_emp;
$ELSE
SELECT *
FROM emp
INTO l_emp
WHERE emp_id = p_emp_id;
RETURN l_emp;
$END
END get_emp;

44. Comparing competing implementations
during prototyping

45. PROCEDURE xyz IS
$IF $$alternative = 1 $THEN
-- varray declaration
$$ELSIF $$alternative = 2 $THEN
-- nested table declaration
$END
BEGIN
$IF $$alternative = 1 $THEN
-- simple varray solution
$$ELSIF $$alternative = 2 $THEN
-- elegant nested table solution
$END
END xyz;
PROCEDURE xyz ISPROCEDURE xyz IS
$IF $$alternative = 1 $THEN$IF $$alternative = 1 $THEN
-- varray declaration-- varray declaration
$$ELSIF $$alternative = 2 $THEN$$ELSIF $$alternative = 2 $THEN
-- nested table declaration-- nested table declaration
$END$END
BEGINBEGIN
$IF $$alternative = 1 $THEN$IF $$alternative = 1 $THEN
-- simple varray solution-- simple varray solution
$$ELSIF $$alternative = 2 $THEN$$ELSIF $$alternative = 2 $THEN
-- elegant nested table solution-- elegant nested table solution
$END$END
END xyz;END xyz;
$IF $$alternative = 1 $THEN
-- first verbose solution that came
to mind
$$ELSIF $$alternative = 2 $THEN
-- some crazy idea you came up with
at 3am you need to try out
$END

46. Component Based Installation

47. PACKAGE BODY core IS
PROCEDURE execute_component(p_choice IN VARCHAR2) IS
BEGIN
CASE p_choice -- Base is always installed.
WHEN 'base' THEN base.main();
$IF CC_licence.cheap_installed $THEN
WHEN 'cheap' THEN cheap.main();
$END
...
$IF CC_licence.pricey_installed $THEN
WHEN 'pricey' THEN pricey.main();
$END
END CASE;
EXCEPTION WHEN case_not_found THEN
dbms_output.put_line('Component '||p_choice||' is
not installed.');
END execute_component;
END core;

48. Get It Right with the Error Directive

49. $IF $$PLSQL_OPTIMIZE_LEVEL != 2
$THEN
$ERROR 'intensive_program must be compiled with
maximum optimisation'
$END
$END

50. BEGIN
...
/*
*
* Note to self: Must remember to finish this bit
*
*/
...
END;

51. BEGIN
...
-- Jacko: this doesn’t work, fix before moving to prod!
...
END;

52. 1 CREATE PROCEDURE process_court_outcome IS
2 BEGIN
3 IF lr_victim.age > 18 THEN
4 send_to_prison(lr_victim);
5 ELSE
6 $ERROR
7 'Waiting for business to advise '||
8 $$PLSQL_UNIT||' line: '||$$PLSQL_LINE
9 $END
10 END IF;
11 END process_court_outcome;
12 /
Warning: Procedure created with compilation errors.
SQL> sho err
LINE/COL ERROR
-------- ----------------------------------------
6/6 PLS-00179: $ERROR: Waiting for business to
advise PROCESS_COURT_OUTCOME line: 8

53. Post-processed Source
Demo: cc2

54. Smaller, Faster Run-Time Code Is in Your Future

55. Good Practices

56. Inquiry directives have null values for normal behaviour
$IF $$cc_flag = 'x' $THEN
cc_code;
$END

57. Choose restriction type carefully
$IF $$debug_on
OR module_y.cc_debug
$THEN
sw_debug('Error');
$END

58. but there’s always this...

59. SQL> define debug=/*
begin
&debug
select 'conditionally'
from dual;
-- */
select 'always'
from dual;
end;
/

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