SAGE Computing Services Customised Oracle Training Workshops and Consulting Creative Conditional Compilation … and raising the bar with your PL/SQL Scott Wesley Systems Consultant

The example everybodys seen…

PL/SQL Users Guide & Reference 10g Release 2 –Fundamentals of the PL/SQL Language Conditional Compilation

Availability 11g Release 1 10g Release 2 –Enabled out of the box – Once patched, enabled by default –Disable using _parameter – Once patched, disabled by default –Enable using _parameter

Catch 22 INDICES OF

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 Semantics

Inquiry Directives

> 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; /

First Demo: Post-processed Source Demo: cc1.sql cc2.sql

Reuse Settings

ALTER SYSTEM 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

Second Demo: Directive Usage Demo: cc3.sql cc4.sql cc5.sql

Some versioning examples?

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

10.1 vs 10.2 dbms_output

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 -- Lets 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;

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...

9i vs 10g Bulk Insert

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 > 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;

Paradigm Examples

Latent debugging code

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 ('Debugging Details'); $END END sw_proc; /

Assertions ?

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

Latent Assertions ?

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;

Mock objects

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 $IF $$alternative = 1 $THEN -- simple varray solution $ELSIF $$alternative = 2 $THEN -- elegant nested table solution $END 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

Component Based Installation

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

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

BEGIN Jacko: this doesnt 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 PLS-00179: $ERROR: Waiting for business to advise PROCESS_COURT_OUTCOME line: 8

CREATE OR REPLACE PACKAGE pkg_debug IS debug_flag CONSTANT BOOLEAN := FALSE; $IF $$CC_dev_notes $THEN PROCEDURE insert_dev_note(p_note IN VARCHAR2,p_unit IN VARCHAR2,p_line IN VARCHAR2) IS PRAGMA AUTONOMOUS TRANSACTION; BEGIN INSERT INTO dev_notes (note, unit, line) VALUES (p_note, p_unit, p_line); END insert_dev_note; $END END pkg_debug; /

CREATE PROCEDURE process_court_outcome IS BEGIN IF lr_victim.age > 18 THEN send_to_prison(lr_victim); ELSE pkg_debug.insert_dev_note ('Waiting for business to advise',$$PLSQL_UNIT,$$PLSQL_LINE); END IF; END process_court_outcome; /

Good Practices

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

but theres always this...

SQL> define debug=/* begin &debug select 'conditionally' into :c1 from dual; -- */ select 'always' into :c2 from dual; end; /

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