Oracle PL/SQL - Creative Conditional Compilation

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Creative Conditional Compilation
… and “raising the bar” with yourPL/SQL
Sco tt We sle y
Systems Consultant

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;

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
$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;

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

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”

Catch 22
Conditional
Compilation
Patch
INDICES OF

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

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

First demo
cc1a
cc1b
cc1c
cc1d

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

> 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

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

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

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;
/

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

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

CREATE OR REPLACE PROCEDURE sw_debug (p_text IN
VARCHAR2) IS
$IF $$sw_debug_on $THEN
l_text VARCHAR2(32767);
$END
BEGIN
-- 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;

CREATE OR REPLACE PROCEDURE sw_debug (p_text INCREATE OR REPLACE PROCEDURE sw_debug (p_text IN
VARCHAR2) ISVARCHAR2) IS
l_text VARCHAR2(32767);
$END
BEGINBEGIN
-- Let’s provide debugging info
$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;

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
$ELSE$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;

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
...

CREATE OR REPLACE PACKAGE BODY sw_bulk_insert IS
PROCEDURE sw_insert (sw_tab IN t_sw_tab) IS
BEGIN
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;

BEGIN
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;

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;

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;
/

“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

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

$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

Testing subprograms only in package body

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;

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;

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;

Comparing competing implementations
during prototyping

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

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;

Get It Right with the Error Directive

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

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

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

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

Post-processed Source
Demo: cc2

Smaller, Faster Run-Time Code Is in Your Future

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

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

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

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Oracle PL/SQL - Creative Conditional Compilation

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